CN110513419A - An adjustable zero-stiffness vibration isolator based on magnetic circuit design - Google Patents

Abstract

The invention discloses an adjustable zero-stiffness vibration isolator based on magnetic circuit design, which relates to the field of vibration control. The guide shaft is installed on the top of the external magnetic conduction shell, and the load platform, elastic parts and adjustment nuts are set sequentially from top to bottom. Installed on the guide shaft, the load platform is connected to the movable shaft through a connecting component, and can move axially together with the movable shaft. It is located at both ends of the movable shaft, coaxial with the movable shaft and has an axial gap. The two ends of each connecting magnetic conducting shaft are respectively connected with the middle magnetic conducting ring and the inner wall of the outer magnetic conducting shell, and each connecting magnetic conducting shaft is respectively sleeved A coil is provided, and an acceleration sensor is fixed on the external magnetically permeable shell, and both the acceleration sensor and the coil are connected with the control system. The device connects the adjustable magnetic negative stiffness mechanism and the positive stiffness elastic element in parallel, realizes low natural frequency while ensuring large load capacity, improves vibration isolation effect, has high energy utilization rate, and is easy to use.

Description

An adjustable zero-stiffness vibration isolator based on magnetic circuit design

technical field

The invention relates to the field of vibration control, in particular to an adjustable zero-stiffness vibration isolator based on magnetic circuit design.

Background technique

Traditional linear vibration isolators, using linear stiffness elements such as coil springs, rubber and air springs, are only suitable for frequencies higher than their natural frequencies Only when the external excitation is doubled can the vibration isolation effect be achieved, but the vibration (resonance) will be amplified in the low frequency region. Reducing the stiffness of the vibration isolator can reduce the natural frequency of the vibration isolator, thereby effectively expanding the vibration isolation frequency band and improving the vibration isolation performance. However, on the one hand, reducing the linear stiffness will reduce the bearing capacity of the vibration isolator, causing excessive static deformation and instability; on the other hand, the stiffness components of the linear vibration Stiff air springs require a lot of volume. In order to solve the inherent contradiction between high vibration isolation performance and high load-carrying capacity, many researchers have proposed to achieve quasi-zero stiffness by parallel connection of positive and negative stiffness, that is, high static and low dynamic stiffness: high static stiffness ensures small deformation and high load-carrying capacity, low dynamic Rigidity guarantees low natural frequency and high vibration isolation performance. Negative stiffness refers to the characteristic that the slope of the load versus displacement curve is negative, as opposed to the common positive stiffness. The negative stiffness is unstable, and the mechanical negative stiffness mechanism is generally composed of several elastic elements, connecting rods and other parts in a special way.

However, the stiffness of most current negative stiffness mechanisms is determined after assembly and cannot be adjusted online. Vibration isolators with constant stiffness cannot cope with changes in excitation frequency, and it is difficult to achieve optimal vibration isolation performance. In recent years, some people have added an actuator to the mechanical negative stiffness mechanism to adjust the stiffness, but its mechanical structure is bulky, its performance is affected by the material and processing conditions of the parts, and there is a dead zone and slow response, so it is difficult to be used in engineering practice. Some people have proposed an electromagnetic negative stiffness mechanism, which is composed of a energized coil and a permanent magnet. The stiffness can be adjusted by controlling the current, but the permanent magnet will demagnetize under high temperature and impact, which prevents the coil from being connected to a large current and causes temperature rise, which also limits The application scenario of the vibration isolator is defined; and the magnetic field distribution is relatively scattered, the utilization rate is low, the magnitude of the negative stiffness is small, and the energy consumption is high, so it is difficult to be used for low-frequency vibration isolation with large loads.

For example, the authorization announcement number proposed by Shanghai University is the electromagnetic negative stiffness spring CN 105927694 B, which uses the magnetic field force between the DC energized coil and the permanent magnet to form a negative stiffness, and can linearly adjust the negative stiffness by controlling the current. However, the distribution of the magnetic field is scattered, and the energy utilization rate of the magnetic field is low.

The authorized announcement number proposed by Harbin Engineering University is the electromagnetic negative stiffness spring of CN 105587812 B. The stator is arranged outside the mover, and coils are wound on the mover. The working surfaces of the mover and stator are provided with a rectangular ring gear. Corresponding to the position of the rectangular ring gear of the stator and there is an air gap between the two, the Maxwell tangential force between the magnetic teeth forms a negative stiffness.

Contents of the invention

In order to solve the above technical problems, the present invention provides an adjustable zero-stiffness vibration isolator based on magnetic circuit design, which can achieve low natural frequency while ensuring large load-carrying capacity, improve the vibration isolation effect, and at the same time have high force density and high energy efficiency , easy to use.

To achieve the above object, the present invention provides the following scheme:

The invention provides an adjustable zero-stiffness vibration isolator based on magnetic circuit design, which includes a load platform, a connecting assembly, a positive stiffness load-bearing module, a negative stiffness magnetic circuit module, and a control system. The negative stiffness magnetic circuit module includes an external guide A magnetic shell, a movable shaft, a middle magnetic conducting ring, two end magnetic conducting shafts and a plurality of connecting magnetic conducting shafts, the positive stiffness bearing module includes a guide shaft, an elastic component and an adjusting nut, and the guide shaft is installed on the The top end of the external magnetically conductive shell, the load platform, the elastic member and the adjusting nut are sleeved and installed on the guide shaft from top to bottom in sequence, and the adjusting nut is threadedly connected with the guide shaft. The load platform is connected to the movable shaft through a connecting assembly, and can move axially together with the movable shaft; In the middle of the shaft, the two end magnetic shafts are arranged coaxially with the movable shaft, and there is a gap between the upper and lower end faces of the movable shaft, and the two end magnetic shafts are respectively fixed on the The top and bottom ends of the external magnetic conduction shell; the coaxial gap of the intermediate magnetic conduction ring is sleeved outside the movable shaft, and the adjusting nut is used to adjust the load platform and the movable shaft connected to it The initial relative position of the intermediate magnetic conduction ring; the two ends of each of the connecting magnetic conduction shafts are respectively connected to the inner wall of the intermediate magnetic conduction ring and the outer magnetic conduction shell, and each of the connected magnetic conduction shafts is respectively A coil is sheathed, and an acceleration sensor is fixed on the outer magnetically conductive shell, and both the acceleration sensor and the coil are connected to the control system.

Preferably, the connection assembly includes a fixed ring and a plurality of connecting rods, the fixed ring is sleeved on the upper end of the movable shaft, and fixed to the movable shaft with set screws in the radial direction, the connection The rods and the guide shafts are parallel to each other, and the two ends of each connecting rod are respectively connected with the load platform and the fixed ring, and each connecting rod runs through the top of the outer magnetically conductive shell and can be opposite to the The outer magnetic shell moves up and down.

Preferably, the control system includes a computer, an analog output module, a power supply and an analog input module, the analog input module and the analog output module are respectively connected to the computer, the acceleration sensor is connected to the analog input module, The power supply is connected to the analog output module, and the coil is connected to the power supply.

Preferably, the movable shaft and the two end magnetically conductive shafts have the same diameter, and the axial height of the movable shaft is higher than the axial height of the middle magnetically conductive ring.

Preferably, the intermediate magnetic conduction ring and the connecting magnetic conduction shaft are perpendicular to each other, the inner ring of the coil is close to the outer ring of the connection magnetic conduction shaft, and when the coil is working, direct current is passed through, so that each of the The direction of the magnetic field generated by the coil points to or deviates from the middle magnetic permeable ring at the same time.

Preferably, a plurality of shaft supports are further included, and each connecting magnetic conduction shaft can be fixed on the inner wall of the outer magnetic conduction shell through one of the shaft supports.

Preferably, a linear bearing is further included, the linear bearing is fixed at the center of the load platform, the guide shaft passes through the linear bearing, and the linear bearing is sleeved on the outside of the guide shaft.

Preferably, the lower end of the guide shaft is screwed to the upper surface of the top end of the outer magnetically permeable shell.

Preferably, the elastic member is a coil spring, rubber or leaf spring.

Compared with the prior art, the present invention has achieved the following technical effects:

The adjustable zero-stiffness vibration isolator based on the magnetic circuit design provided by the present invention includes a load platform, a connection assembly, a positive stiffness load-bearing module, a negative stiffness magnetic circuit module, and a control system. The magnetic circuit design of the negative stiffness magnetic circuit module makes the magnetic field Concentrated and distributed in the designed magnetic circuit, which greatly improves the utilization rate of the magnetic field. Using Maxwell's normal force, it can achieve greater negative stiffness with less power, and can be connected in parallel with greater positive stiffness. Realize quasi-zero stiffness, and then can be used for low-frequency vibration isolation of large loads, achieve low natural frequency while ensuring large load-carrying capacity, improve vibration isolation effect, high energy utilization rate, easy to use, and there is no permanent magnet in the entire magnetic circuit system The presence of magnets can be used in high temperature environments. By setting the control system to control the magnitude of the current, the magnitude of the negative stiffness generated by the magnetic circuit can be changed, that is, the natural frequency of the vibration isolator can be changed, thereby avoiding low-frequency resonance and further improving the vibration isolation effect.

Description of drawings

In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the accompanying drawings required in the embodiments. Obviously, the accompanying drawings in the following description are only some of the present invention. Embodiments, for those of ordinary skill in the art, other drawings can also be obtained based on these drawings without any creative effort.

1 is a schematic diagram of the system composition of an adjustable zero-stiffness vibration isolator based on magnetic circuit design provided by the present invention;

Fig. 2 is an isometric view of the adjustable zero-stiffness vibration isolator based on the magnetic circuit design provided by the present invention.

Explanation of reference signs: 1. External magnetic shell; 2. End magnetic shaft; 3. Shaft support; 4. Connecting magnetic shaft; 5. Intermediate magnetic ring; 6. Movable shaft; 7. Adjusting nut ; 8, elastic component; 9, linear bearing; 10, guide shaft; 11, load platform; 12, connecting rod; 13, fixed ring; 14, coil; 15, acceleration sensor; 16, computer; 17, analog output module; 18. Power supply; 19. Analog input module.

Detailed ways

The following will clearly and completely describe the technical solutions in the embodiments of the present invention with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only some, not all, embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by persons of ordinary skill in the art without making creative efforts belong to the protection scope of the present invention.

The purpose of the present invention is to provide an adjustable zero-stiffness vibration isolator based on magnetic circuit design, which can achieve low natural frequency while ensuring large load capacity, improve the vibration isolation effect, and at the same time have high force density, high energy efficiency, and easy use .

In order to make the above objects, features and advantages of the present invention more comprehensible, the present invention will be further described in detail below in conjunction with the accompanying drawings and specific embodiments.

As shown in Figure 1-2, this embodiment provides an adjustable zero-stiffness vibration isolator based on magnetic circuit design, including a load platform 11, a connection assembly, a positive stiffness load-bearing module, a negative stiffness magnetic circuit module, and a control system. The negative stiffness magnetic circuit module includes an outer magnetic shell 1, a movable shaft 6, a middle magnetic ring 5, two end magnetic shafts 2 and a plurality of connecting magnetic shafts 4, and the positive stiffness load-bearing module includes a guide shaft 10, an elastic Part 8 and adjusting nut 7. The guide shaft 10 is installed on the top of the outer magnetically conductive shell 1, and the load platform 11, the elastic member 8 and the adjustment nut 7 are sleeved and installed on the guide shaft 10 from top to bottom in sequence. In this specific embodiment, the guide shaft 10 consists of The polished rod section, the threaded section and the connecting section are sequentially connected from top to bottom. The load platform 11 is sleeved on the polished rod section. The load platform 11 can move axially along the guide shaft 10. The adjusting nut 7 is installed on the threaded section. The guide shaft 10 Its lower end is screwed and fixedly connected to the upper surface of the top end of the outer magnetic permeable shell 1 . The load platform 11 presses the elastic part 8 to the upper end of the adjustment nut 7. The elastic part 8 is used to support a large load. When the load remains unchanged, the compression amount of the elastic part 8 is determined. The load platform 11 can be adjusted by rotating the adjustment nut 7. the initial position of . When there is no negative stiffness generated by the magnetic circuit, there is only positive stiffness generated by the elastic component 8, and the vibration isolator is at a high natural frequency. Specifically, the elastic member 8 is a coil spring, rubber or leaf spring.

The load platform 11 is connected to the movable shaft 6 through a connecting assembly, and can move axially together with the movable shaft 6. The movable shaft 6 is arranged in the middle of the two end magnetic conduction shafts 2 in the outer magnetic conduction shell 1, and the two The end magnetic conducting shaft 2 is coaxially arranged with the movable shaft 6, and there is a gap between the upper and lower end surfaces of the movable shaft 6, and the two end magnetic conducting shafts 2 are respectively fixed on the top and bottom ends of the outer magnetic conducting shell 1 , the axial gap formed between the movable shaft 6 and the two end magnetic shafts 2 is determined by the working stroke of the vibration isolator. The coaxial gap of the middle magnetic ring 5 is sleeved on the outside of the movable shaft 6. The radial gap between the outer ring surface of the movable shaft 6 and the inner ring face of the middle magnetic ring 5 is very small, and the elastic part 8 is pressed against the adjusting nut. On 7, the adjusting nut 7 can adjust the initial relative position of the load platform 11 and the movable shaft 6 connected to it with the intermediate magnetic conduction ring 5; The inner wall of the shell 1 is connected, and a coil 14 is sleeved on each connected magnetic shaft 4, and the inner ring of the coil 14 is close to the outer ring connected to the magnetic shaft 4. When the coil 14 is working, a direct current is connected to each coil 14. The direction of the magnetic field points to or deviates from the middle magnetic permeable ring 5 at the same time. The entire magnetic circuit is that the coil 14 is energized to generate a magnetomotive force, which connects the magnetically conductive shaft 4 to the middle magnetically conductive ring 5, enters the movable shaft 6 through a small air gap on the annulus, and passes through the upper and lower end surfaces of the movable shaft 6 through the axial direction. The air gap enters the upper and lower ends of the magnetic shaft 2 respectively, and finally passes through the outer magnetic shell 1 and returns to the magnetic shaft 4 to close. The entire magnetic circuit is in the shape of an "8" at the cross-section of each shaft connected to the magnetic shaft 4. (As shown by the dotted line in Figure 1), such a magnetic circuit is designed to produce negative stiffness. In this specific embodiment, the parts that the magnetic circuit passes through are all made of materials with high magnetic permeability such as electrical pure iron except for the air gap, and other parts are made of materials with low magnetic permeability such as 304 steel or aluminum alloy, that is, the external magnetic permeability The shell 1, the movable shaft 6, the middle magnetic ring 5, the two end magnetic shafts 2 and the connecting magnetic shafts 4 are all made of materials with high magnetic permeability such as electrician pure iron. The components are all made of low magnetic permeability materials such as 304 steel or aluminum alloy.

An acceleration sensor 15 is fixed on the outer magnetically permeable shell 1, and both the acceleration sensor 15 and the coil 14 are connected with the control system. Specifically, the bottom of the outer magnetically permeable shell 1 is used to be installed on the base, and the acceleration sensor 15 is used to collect acceleration signals of vibration of the base.

Control system comprises computer 16, analog output module 17, power supply 18 and analog input module 19, and analog input module 19 and analog output module 17 are connected with computer 16 respectively, and acceleration sensor 15 is connected with analog input module 19, and power supply 18 is connected with analog output module 17 is connected, and the coil 14 is connected with the power supply 18.

Specifically, the connection assembly includes a fixed ring 13 and a plurality of connecting rods 12. The fixed ring 13 is sleeved on the upper end of the movable shaft 6, and is fixed to the movable shaft 6 with set screws in the radial direction. The connecting rods 12 and the guide shaft 10 are parallel to each other, and the two ends of each connecting rod 12 are respectively connected with the load platform 11 and the fixed ring 13 , and each connecting rod 12 runs through the top of the outer magnetic permeable shell 1 and can move up and down relative to the outer magnetic permeable shell 1 . In this specific embodiment, there are two connecting rods 12 .

Specifically, the diameters of the movable shaft 6 and the two ends of the magnetically conductive shafts 2 are equal. The axial height of the movable shaft 6 is higher than that of the middle magnetic permeable ring 5 . The middle magnetic conduction ring 5 is perpendicular to the connecting magnetic conduction shaft 4 . This embodiment also includes a plurality of shaft supports 3 , and each connecting magnetically conductive shaft 4 can be fixed on the inner wall of the outer magnetically conductive shell 1 through one shaft support 3 .

In this specific embodiment, the external magnetic shell 1 includes a cross-shaped top plate, a cross-shaped bottom plate and four side plates, and the upper and lower ends of each side plate are fixedly connected to the cross-shaped top plate and the cross-shaped bottom plate respectively. The two end magnetic shafts 2 are respectively fixed on the lower end of the cross-shaped top plate and the upper end of the cross-shaped bottom plate, the acceleration sensor 15 is arranged on the cross-shaped bottom plate, and a shaft support 3 is installed on the inner wall of each side plate, that is, in this embodiment In the example, the shaft support 3, the connecting magnetic shaft 4 and the coil 14 are all set to four.

In this embodiment, a linear bearing 9 is also included. The linear bearing 9 is fixed at the center of the loading platform 11 . The guide shaft 10 passes through the linear bearing 9 , and the linear bearing 9 is sleeved on the outside of the guide shaft 10 . The friction is reduced by setting the linear bearing 9, that is, the damping rate of the system is reduced.

When the vibration isolator is working, the two ends of the magnetically conductive shafts 2 attract the movable shaft 6, and the attractive force reduces the axial air gap, and it is obvious that the smaller the air gap, the greater the attractive force. That is to say, when the movable shaft 6 is in the middle position of the middle magnetic conduction ring 5, the attractive forces of the two end magnetic conduction shafts 2 on the movable shaft 6 are equal, and the magnetic negative stiffness is in a balanced position. This is the vibration isolator Ideal initial position for the system. However, once a slight disturbance occurs to make the movable shaft 6 leave the equilibrium position, the movable shaft 6 will continue to move away from the equilibrium position, and cannot return without external force. It can be seen that a negative stiffness is formed between the movable shaft 6 and the end magnetically conductive shaft 2 . However, the positive stiffness force of the coil spring will make the load platform 11 return to the equilibrium position after it deviates from the equilibrium position. The negative stiffness generated by the magnetic circuit is connected in parallel with the positive stiffness generated by the helical spring. The force of the positive stiffness returning to the equilibrium position and the force of the negative stiffness moving away from the equilibrium position cancel each other out, which can produce quasi-zero stiffness, and the vibration isolator is at a low natural frequency to achieve good vibration isolation effect. In the initial working position without vibration, the center of the movable shaft 6 and the center of the intermediate magnetic ring 5 should be at the same height. The position of the moving shaft 6 is such that the magnetic negative stiffness is in a balanced position, and the vibration isolator reaches an ideal initial position.

However, under the current technical conditions, the quasi-zero stiffness is still a certain distance from the true zero stiffness, and the low natural frequency has not been reduced to 0, and the vibration isolator may still resonate at this low natural frequency. By controlling the magnitude of the current, the negative stiffness generated by the magnetic circuit can be changed, that is, the natural frequency of the vibration isolator can be changed, thereby avoiding low-frequency resonance and further improving the vibration isolation effect. The specific implementation method is: acceleration sensor 15 collects the acceleration signal of foundation base vibration, is converted into digital signal by analog input module 19 and sends to computer 16, and computer 16 calculates the main frequency of external vibration by frequency detection algorithm; When external main vibration frequency is higher than The low natural frequency of the vibration isolator times, the computer 16 outputs a signal, which is converted into an analog signal through the analog output module 17, and finally converted into a driving current by the power supply 18 and sent to the coil 14 to generate negative stiffness. At this time, the vibration isolator is at quasi-zero stiffness and the natural frequency lower, the vibration isolation effect is better; when the external excitation frequency is close to the low natural frequency of the vibration isolator, the vibration isolator may resonate, at this time, the computer 16 outputs a signal, the power supply 18 is turned off, and the negative stiffness disappears, then it can be switched to High natural frequency of positive stiffness isolators to avoid resonance.

It can be seen that the adjustable zero-stiffness vibration isolator based on the magnetic circuit design provided in this embodiment, the magnetic circuit design of the negative stiffness magnetic circuit module makes the magnetic field concentrated and distributed in the designed magnetic circuit, the magnetic field distribution is excellent, and the pole The utilization rate of the magnetic field is greatly improved. Using the Maxwell normal force, a greater negative stiffness can be achieved with less power, that is, the energy utilization rate is high and the negative stiffness level is high, which can be compared with a larger positive stiffness. Parallel connection of stiffnesses achieves quasi-zero stiffness, which in turn can be used for low-frequency vibration isolation of large loads, achieving low natural frequency while ensuring large load-carrying capacity, improving vibration isolation effects, high energy efficiency, and easy to use, and there is no The presence of permanent magnets can be used in high temperature environments. By setting the control system to control the magnitude of the current, the magnitude of the negative stiffness generated by the magnetic circuit can be changed, that is, the natural frequency of the vibration isolator can be changed, thereby avoiding low-frequency resonance and further improving the vibration isolation effect.

In this description, specific examples are used to illustrate the principle and implementation of the present invention. The description of the above embodiments is only used to help understand the method and core idea of the present invention; meanwhile, for those of ordinary skill in the art, according to this The idea of the invention will have changes in the specific implementation and scope of application. In summary, the contents of this specification should not be construed as limiting the present invention.

Claims (9)

1. An adjustable zero-stiffness vibration isolator based on magnetic circuit design, characterized in that it includes a load platform, a connection assembly, a positive stiffness load-bearing module, a negative stiffness magnetic circuit module and a control system, and the negative stiffness magnetic circuit module It includes an outer magnetic shell, a movable shaft, a middle magnetic ring, two end magnetic shafts and a plurality of connecting magnetic shafts. The positive stiffness load-bearing module includes a guide shaft, an elastic component and an adjusting nut. The guide shaft Installed on the top of the external magnetic shell, the load platform, the elastic member and the adjusting nut are sleeved and installed on the guide shaft from top to bottom in sequence, and the adjusting nut is threaded with the guide shaft connected, the load platform is connected to the movable shaft through a connecting assembly, and can move axially together with the movable shaft; In the middle of the first magnetic shaft, the two end magnetic shafts are coaxially arranged with the movable shaft, and there is a gap between the upper and lower end faces of the movable shaft, and the two end magnetic shafts are respectively fixed on the top and bottom ends of the external magnetic shell; the coaxial gap of the middle magnetic ring is sleeved outside the movable shaft, and the adjusting nut is used to adjust the load platform and the The initial relative position of the movable shaft and the intermediate magnetic conduction ring; the two ends of each of the connecting magnetic conduction shafts are respectively connected to the inner wall of the intermediate magnetic conduction ring and the outer magnetic conduction shell, and each of the connected magnetic conduction A coil is respectively sleeved on the shaft, and an acceleration sensor is fixed on the outer magnetically conductive shell, and both the acceleration sensor and the coil are connected to the control system. 2. The adjustable zero-stiffness vibration isolator based on magnetic circuit design according to claim 1, wherein the connecting assembly includes a fixed ring and a plurality of connecting rods, and the fixed ring is sleeved on the adjustable The upper end of the moving shaft is fixed to the moving shaft with set screws in the radial direction, the connecting rods are parallel to the guide shaft, and the two ends of each connecting rod are respectively connected to the load platform and the The fixing ring is connected, and each of the connecting rods passes through the top of the outer magnetic conduction shell and can move up and down relative to the outer magnetic conduction shell. 3. The adjustable zero-stiffness vibration isolator based on magnetic circuit design according to claim 1, wherein the control system includes a computer, an analog output module, a power supply and an analog input module, and the analog input module and The analog output modules are respectively connected to the computer, the acceleration sensor is connected to the analog input module, the power supply is connected to the analog output module, and the coil is connected to the power supply. 4. The adjustable zero-stiffness vibration isolator based on magnetic circuit design according to claim 1, wherein the diameter of the movable shaft and the two magnetically conductive shafts at the ends are equal, and the movable shaft The axial height is higher than the axial height of the middle magnetic permeable ring. 5. The adjustable zero-stiffness vibration isolator based on magnetic circuit design according to claim 4, characterized in that, the middle magnetic conduction ring and the connecting magnetic conduction axis are perpendicular to each other, and the inner ring of the coil is tightly The outer ring connected to the magnetic conduction shaft is pasted, and the direct current is supplied to the coils during operation, so that the directions of the magnetic fields generated by each of the coils point to or deviate from the middle magnetic conduction ring at the same time. 6. The adjustable zero-stiffness vibration isolator based on magnetic circuit design according to claim 5, characterized in that, it also includes a plurality of shaft supports, and each of the connecting magnetic transmission shafts can pass through one of the shaft supports It is fixed on the inner wall of the outer magnetic conduction shell. 7. The adjustable zero-stiffness vibration isolator based on magnetic circuit design according to claim 1, further comprising a linear bearing, the linear bearing is fixed at the center of the load platform, and the guide shaft passes through passing through the linear bearing, and the linear bearing is sleeved on the outside of the guide shaft. 8 . The adjustable zero-stiffness vibration isolator based on magnetic circuit design according to claim 1 , wherein the lower end of the guide shaft is screwed to the upper surface of the top end of the outer magnetically permeable shell. 9. The adjustable zero-stiffness vibration isolator based on magnetic circuit design according to claim 1, characterized in that, the elastic member is a coil spring, rubber or leaf spring.