A quasi-zero stiffness vibration isolator with large displacement

Abstract

A quasi-zero stiffness vibration isolator with a large displacement stroke, the vibration isolator comprises an upper shell, an upper magnetic ring upper cover, an upper cross spring leaf, an upper spring leaf fastener, an outer magnetic ring shell, an outer magnetic ring base, an outer magnetic ring and an outer magnetic ring upper cover, a lower shell, a lower magnetic ring, a lower magnetic ring lower cover, a lower cross spring leaf and a lower spring leaf fastener, an inner magnetic ring base, an inner magnetic ring and an inner magnetic ring upper cover; the upper and lower magnetic rings and the inner and outer magnetic rings constitute a linear negative stiffness magnetic spring with a large displacement stroke; the upper cross spring leaf and the lower cross spring leaf connect the support rod and the shell, provide positive stiffness of the vibration isolator, and are connected in parallel with the negative stiffness magnetic spring to reduce the dynamic stiffness of the inner magnetic ring at the equilibrium position; the cross spring leaf is equipped with a spring leaf fastener to facilitate adjustment of the equilibrium position; the present invention has the advantages of simple structure and large working stroke, can effectively reduce the natural frequency of the vibration isolation system, widen the vibration isolation frequency band, and improve the vibration isolation effect, and is not only suitable for micro-vibration isolation, but also for large-scale vibration isolation.

Description

Technical Field

[0001] The present invention relates to the technical field of low-frequency passive vibration isolation, and in particular to a quasi-zero-stiffness vibration isolator with a large displacement stroke. Background Art

[0002] The traditional linear passive vibration isolation system has the disadvantage that the load-bearing capacity and the vibration isolation frequency band constrain each other. Connecting positive stiffness springs and negative stiffness springs in parallel can solve this problem well. However, the traditional positive and negative stiffness parallel vibration isolators have the limitation of a small working stroke. The reason is that the negative stiffness provided by the negative stiffness unit increases with the increase of displacement, and can only maintain good linearity near the equilibrium position. The positive stiffness unit of the traditional positive and negative stiffness unit parallel vibration isolator often adopts a linear spring, and the positive stiffness does not change much with displacement. Then the quasi-zero stiffness area of ​​the total stiffness of the traditional positive and negative stiffness unit parallel vibration isolator can only be maintained within a small distance close to the equilibrium position, which limits the working displacement stroke of the traditional positive and negative stiffness unit parallel vibration isolators. Summary of the Invention

[0003] In order to solve the problems existing in the above-mentioned prior art, the purpose of the present invention is to provide a quasi-zero stiffness vibration isolator with a large displacement stroke. By connecting a positive stiffness spring sheet and a linear negative stiffness magnetic spring with a large displacement stroke in parallel, the vibration isolator can achieve high static stiffness and low dynamic stiffness characteristics with a large displacement stroke. While ensuring the bearing capacity of the vibration isolator, it can also widen the vibration isolation frequency band in the low-frequency direction and achieve a larger working stroke.

[0004] In order to achieve the above purpose, the present invention adopts the following technical solutions:

[0005] A quasi-zero stiffness vibration isolator with a large displacement stroke includes an upper structure, a lower structure, a middle outer structure and a middle inner structure and a support rod 18. The upper structure includes an upper shell 1, an upper magnetic ring 2, an upper magnetic ring cover 3, an upper cross spring leaf 4 and an upper spring leaf fastener 5. The upper magnetic ring 2 is installed in the internal groove of the upper shell 1, and the upper magnetic ring cover 3 is installed above the upper magnetic ring 2. The upper magnetic ring cover 3 is fixed to the upper shell 1 by bolts, and the upper cross spring leaf 4 and the upper spring leaf fastener 5 are fixed to form an upper spring. The upper spring is fixed to the upper shell 1 by bolts, and the upper spring is kept in the upper shell 1. The spring fastener 5 is on the top; the middle and outer structures include an outer magnetic ring shell 6, an outer magnetic ring base 7, an outer magnetic ring 8 and an outer magnetic ring upper cover 9, the outer magnetic ring base 7 is installed in the groove of the outer magnetic ring shell 6, the outer magnetic ring 8 is installed on the outer magnetic ring base 7, the outer magnetic ring upper cover 9 is installed on the outer magnetic ring 8, and the outer magnetic ring upper cover 9 has a through hole, which is coaxially arranged with the through hole of the outer magnetic ring shell 6; the lower structure includes a lower shell 10, a lower magnetic ring 11, a lower magnetic ring lower cover 12, a lower cross spring leaf 13 and a lower spring leaf fastener 14, the lower magnetic ring 11 is installed in the internal groove of the lower shell 10, and the lower magnetic ring lower cover 12 is installed below the lower magnetic ring 11, and The lower magnetic ring lower cover 12 is fixed to the lower shell 10 by bolts, the lower cross spring leaf 13 and the lower spring leaf fastener 14 are fixed to form a lower spring, and the lower spring and the lower shell 10 are fixed by bolts, and the lower spring leaf fastener 14 is kept at the bottom; the internal structure includes an inner magnetic ring base 15, an inner magnetic ring 16 and an inner magnetic ring upper cover 17, the inner magnetic ring 16 is installed in the inner groove of the inner magnetic ring base 15, the inner magnetic ring upper cover 17 is installed above the inner magnetic ring 16, and the inner magnetic ring upper cover 17 and the inner magnetic ring base 15 are connected and fixed by bolts; the bottom of the upper shell 1 and the top of the lower shell 10 The outer magnetic ring shell 6 is provided with through holes all around, and the three are connected and fixed by bolts, so the upper structure, the middle and outer structure and the lower structure are connected and fixed, the middle part of the support rod 18 matches the central threaded hole of the inner magnetic ring base 15, and the two are fixed by threaded connection, the upper part of the support rod 18 matches the threaded hole of the upper spring sheet fastener 5, and the two are fixed by threaded connection, the lower part of the support rod 18 matches the threaded hole of the lower spring sheet fastener 14, and the two are fixed by threaded connection, and the relative position of the inner magnetic ring 16 is adjusted by rotating the support rod 18 during installation; the lower part of the lower shell 10 is provided with a through hole and connected to the foundation.

[0006] The upper magnetic ring 2, the lower magnetic ring 11, the outer magnetic ring 8 and the inner magnetic ring 16 constitute a magnetic spring with a large displacement stroke and linear negative stiffness; the upper cross spring leaf 4 and the lower cross spring leaf 13 are connected to the support rod 18 and are respectively connected to the upper shell 1 and the lower shell 10, providing positive stiffness of the vibration isolator, and being connected in parallel with the magnetic spring with a large displacement stroke and linear negative stiffness, thereby reducing the dynamic stiffness of the inner magnetic ring 16 at the equilibrium position.

[0007] The quasi-zero stiffness vibration isolator with a large displacement stroke is described. The vibration isolation object is placed on the upper part of the support rod 18. When the vibration isolation object is disturbed in the vertical direction, the disturbance is transmitted to the inner magnetic ring 16 through the support rod 18, causing the inner magnetic ring 16 to undergo a relative displacement z relative to the outer magnetic ring 8, the upper magnetic ring 2 and the lower magnetic ring 11. During this process, the inner magnetic ring 16 is subjected to the magnetic force F of the upper magnetic ring 2, the lower magnetic ring 11 and the outer magnetic ring 8. m Given the geometric dimensions and magnetization strengths of the inner magnetic ring 16, the outer magnetic ring 8, the upper magnetic ring 2 and the lower magnetic ring 11, the equivalent magnetic charge method can be used to calculate the magnetic force F acting on the inner magnetic ring at any position. m When the magnetization directions of the inner magnetic ring 16, the outer magnetic ring 8, the upper magnetic ring 2 and the lower magnetic ring 11 are all upward, the magnetic force F m It manifests as negative stiffness, that is, the direction of the magnetic force is consistent with the direction of the relative displacement z; then according to the equivalent magnetic charge method, the negative derivative of the magnetic force with respect to the relative displacement z can be obtained, that is, the magnetic negative stiffness K n , the magnetic force F m The Taylor expansion F is performed at the equilibrium position z=0 of the inner magnetic ring 16. m =-K0z+ε3z 3 +ε5z 5 , where K0 is the negative magnetic stiffness K n The size of the inner magnetic ring 16 at the equilibrium position represents the magnetic force F m The linear part, ε3 and ε5 are the coefficients of the cubic and quintic terms, respectively, which measure the magnetic force F m The nonlinear size of ε3 and ε5 is smaller, and the magnetic force F m The stronger the linearity, the more K0, ε3 and ε5 are related to the geometric dimensions of the inner magnetic ring 16, the outer magnetic ring 8, the upper magnetic ring 2 and the lower magnetic ring 11 and their respective magnetization intensities; the absolute value of the product of the coefficients ε3 and ε5 of the cubic term and the quintic term is used as the objective function f=ε3·ε5, the inner diameter of the outer magnetic ring 8, the outer diameter of the outer magnetic ring 8, the thickness of the outer magnetic ring 8, the inner diameter of the upper magnetic ring 2 and the outer diameter of the upper magnetic ring 2 are used as optimization parameters, and the genetic algorithm is used for optimization to minimize the objective function. At this time, the magnetic force F m The linearity is strongest near the equilibrium position of the inner magnetic ring 16, that is, the magnetic force F m The total negative magnetic stiffness K remains unchanged within a displacement range near the equilibrium position of the inner magnetic ring 16. n It will offset part of the positive stiffness K provided by the upper cross spring piece 4 and the lower cross spring piece 13 p , so that the dynamic stiffness K of the isolator near the equilibrium position of the inner magnetic ring 16 D =K p +K n Compared with the dynamic stiffness K′ of the structure without the inner magnetic ring 16, the outer magnetic ring 8, the upper magnetic ring 2 and the lower magnetic ring 11 D=K p Reduce or even approach zero, thereby reducing the resonant frequency of the vibration isolator; the static stiffness K of the structure S Equal to the positive stiffness K provided by the upper cross spring leaf 4 and the lower cross spring leaf 13 p Therefore, the static stiffness is not affected by the negative magnetic stiffness, and the static load-bearing capacity remains unchanged; the negative magnetic stiffness makes the dynamic stiffness K of the isolator D The negative magnetic stiffness obtained by genetic algorithm optimization has the largest linearity near the equilibrium position of the inner magnetic ring 16, while the positive stiffness K p It also remains linear near the equilibrium position of the inner magnetic ring 16, so the total dynamic stiffness K D The linearity is maximum near the equilibrium position of the inner magnetic ring 16, which widens the working displacement stroke of the vibration isolator.

[0008] The upper shell 1, upper magnetic ring upper cover 3, upper cross spring leaf 4, upper spring leaf fastener 5, outer magnetic ring shell 6, outer magnetic ring base 7, outer magnetic ring upper cover 9, lower shell 10, lower magnetic ring lower cover 12, lower cross spring leaf 13, lower spring leaf fastener 14, inner magnetic ring base 15 and inner magnetic ring upper cover 17 are all made of hard aluminum alloy material.

[0009] The upper magnetic ring 2 , the outer magnetic ring 8 , the lower magnetic ring 11 and the inner magnetic ring 16 are all made of neodymium iron boron material, with an N pole on the upper side along the axial direction and an S pole on the lower side along the axial direction.

[0010] The bolts and nuts are made of non-magnetic conductive materials.

[0011] The upper magnetic ring 2 and the lower magnetic ring 11 are arranged symmetrically about the outer magnetic ring, and the inner diameter, outer diameter and thickness of the upper magnetic ring 2 are exactly the same as those of the lower magnetic ring 11 .

[0012] Compared with the prior art, the present invention has the following advantages: the quasi-zero stiffness isolator of the present invention has a large static stiffness to support the vibration isolation object and has good stability. The dynamic stiffness of the isolator when vibrating near the equilibrium position is low, and it has a good low-frequency vibration isolation effect. At the same time, the isolator can maintain good linear stiffness within a large displacement range near the equilibrium position, so that the working displacement range of the isolator remains within the large displacement range, which is suitable for low-frequency vibration isolation applications with large vibration. The quasi-zero stiffness isolator with a large displacement range of the present invention has a simple structure, is easy to manufacture and install, and can be adjusted by rotating the support rod to achieve the optimal working state of the isolator. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] Figure 1 This is a schematic diagram of a quasi-zero stiffness vibration isolator with large displacement stroke according to the present invention.

[0014] Figure 2This is a cross-sectional view of the quasi-zero stiffness vibration isolator with large displacement stroke according to the present invention.

[0015] Figure 3 It is a cross-sectional view of the upper structure of the present invention.

[0016] Figure 4 It is a cross-sectional view of the external structure of the present invention.

[0017] Figure 5 It is a cross-sectional view of the lower structure of the present invention.

[0018] Figure 6 It is a cross-sectional view of the internal structure of the present invention.

[0019] Figure 7 This is a schematic diagram of the cross spring piece of the present invention. DETAILED DESCRIPTION

[0020] The present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0021] like Figure 1 、 Figure 2 、 Figure 3 、 Figure 4 、 Figure 5 、 Figure 6 and Figure 7As shown, the present invention provides a quasi-zero stiffness vibration isolator with a large displacement stroke, including an upper structure, a lower structure, a middle external structure, a middle internal structure and a support rod 18. The upper structure includes an upper shell 1, an upper magnetic ring 2, an upper magnetic ring upper cover 3, an upper cross spring leaf 4 and an upper spring leaf fastener 5. The upper magnetic ring 2 is installed in the internal groove of the upper shell 1, and the upper magnetic ring upper cover 3 is installed above the upper magnetic ring 2. The upper magnetic ring upper cover 3 and the upper shell 1 are fixed by bolts, and the upper cross spring leaf 4 and the upper spring leaf fastener 5 are fixed by bolts to form an upper spring, and the upper spring and the upper shell 1 are fixed by bolts. And keep the upper spring leaf fastener 5 at the top; the middle and external structure includes an outer magnetic ring shell 6, an outer magnetic ring base 7, an outer magnetic ring 8 and an outer magnetic ring upper cover 9, the outer magnetic ring base 7 is installed in the groove of the outer magnetic ring shell 6, the outer magnetic ring 8 is installed on the outer magnetic ring base 7, the outer magnetic ring upper cover 9 is installed on the outer magnetic ring 8, and the outer magnetic ring upper cover 9 has a through hole, which is coaxially arranged with the through hole of the outer magnetic ring shell 6; the lower structure includes a lower shell 10, a lower magnetic ring 11, a lower magnetic ring lower cover 12, a lower cross spring leaf 13 and a lower spring leaf fastener 14, the lower magnetic ring 11 is installed in the internal groove of the lower shell 10, and the lower magnetic ring lower cover 12 is installed below the lower magnetic ring 11 , and the lower magnetic ring lower cover 12 is fixed to the lower shell 10 by bolts, the lower cross spring leaf 13 and the lower spring leaf fastener 14 are fixed to form a lower spring, and the lower spring and the lower shell 10 are fixed by bolts, and the lower spring leaf fastener 14 is kept at the bottom; the internal structure includes an inner magnetic ring base 15, an inner magnetic ring 16 and an inner magnetic ring upper cover 17, the inner magnetic ring 16 is installed in the inner groove of the inner magnetic ring base 15, the inner magnetic ring upper cover 17 is installed above the inner magnetic ring 16, and the inner magnetic ring upper cover 17 and the inner magnetic ring base 15 are connected and fixed by bolts; the bottom of the upper shell 1 and the top of the lower shell 10 The upper part and the outer magnetic ring shell 6 are provided with through holes, and the three are connected and fixed by bolts, so the upper structure, the middle and outer structure and the lower structure are connected and fixed, the middle part of the support rod 18 matches the central threaded hole of the inner magnetic ring base 15, and the two are fixed by threaded connection, the upper part of the support rod 18 matches the threaded hole of the upper spring sheet fastener 5, and the two are fixed by threaded connection, the lower part of the support rod 18 matches the threaded hole of the lower spring sheet fastener 14, and the two are fixed by threaded connection, and the relative position of the inner magnetic ring 16 is adjusted by rotating the support rod 18 during installation; the lower part of the lower shell 10 is provided with a through hole and connected to the foundation. The upper magnetic ring 2, the lower magnetic ring 11, the outer magnetic ring 8 and the inner magnetic ring 16 constitute a magnetic spring with a large displacement stroke and linear negative stiffness; the upper cross spring leaf 4 and the lower cross spring leaf 13 are connected to the support rod 18 and are respectively connected to the upper shell 1 and the lower shell 10, providing positive stiffness of the vibration isolator, and being connected in parallel with the magnetic spring with a large displacement stroke and linear negative stiffness, thereby reducing the dynamic stiffness of the inner magnetic ring 16 at the equilibrium position.

[0022] like Figure 1 and Figure 2As shown, the vibration isolation object is placed on the upper part of the support rod 18. When the vibration isolation object is disturbed in the vertical direction, the disturbance will be transmitted to the inner magnetic ring 16 through the support rod 18, causing the inner magnetic ring 16 to undergo a relative displacement z relative to the outer magnetic ring 8, the upper magnetic ring 2 and the lower magnetic ring 11. During this process, the inner magnetic ring 16 will be subjected to the magnetic force F of the upper magnetic ring 2, the lower magnetic ring 11 and the outer magnetic ring 8. m Given the geometric dimensions and magnetization strengths of the inner magnetic ring 16, the outer magnetic ring 8, the upper magnetic ring 2 and the lower magnetic ring 11, the equivalent magnetic charge method can be used to calculate the magnetic force F acting on the inner magnetic ring at any position. m When the magnetization directions of the inner magnetic ring 16, the outer magnetic ring 8, the upper magnetic ring 2 and the lower magnetic ring 11 are all upward, the magnetic force F m It manifests as negative stiffness, that is, the direction of the magnetic force is consistent with the direction of the relative displacement z; then according to the equivalent magnetic charge method, the negative derivative of the magnetic force with respect to the relative displacement z can be obtained, that is, the magnetic negative stiffness K n , the magnetic force F m The Taylor expansion F is performed at the equilibrium position z=0 of the inner magnetic ring 16. m =-K0z+ε3z 3 +ε5z 5 , where K0 is the negative magnetic stiffness K n The size of the inner magnetic ring 16 at the equilibrium position represents the magnetic force F m The linear part, ε3 and ε5 are the coefficients of the cubic and quintic terms, respectively, which measure the magnetic force F m The nonlinear size of ε3 and ε5 is smaller, and the magnetic force F m The stronger the linearity, the more K0, ε3 and ε5 are related to the geometric dimensions of the inner magnetic ring 16, the outer magnetic ring 8, the upper magnetic ring 2 and the lower magnetic ring 11 and their respective magnetization intensities; the absolute value of the product of the coefficients ε3 and ε5 of the cubic term and the quintic term is used as the objective function f = |ε3·ε5|, the inner diameter of the outer magnetic ring 8, the outer diameter of the outer magnetic ring 8, the thickness of the outer magnetic ring 8, the inner diameter of the upper magnetic ring 2 and the outer diameter of the upper magnetic ring 2 are used as optimization parameters, and the genetic algorithm is used for optimization to minimize the objective function. At this time, the magnetic force F m The linearity is strongest near the equilibrium position of the inner magnetic ring 16, that is, the magnetic force F m The total negative magnetic stiffness K remains unchanged within a displacement range near the equilibrium position of the inner magnetic ring 16. n It will offset part of the positive stiffness K provided by the upper cross spring piece 4 and the lower cross spring piece 13 p , so that the dynamic stiffness K of the isolator near the equilibrium position of the inner magnetic ring 16 D =K p +K n Compared with the dynamic stiffness K′ of the structure without the inner magnetic ring 16, the outer magnetic ring 8, the upper magnetic ring 2 and the lower magnetic ring 11 D =K pReduce or even approach zero, thereby reducing the resonant frequency of the vibration isolator; the static stiffness K of the structure S Equal to the positive stiffness K provided by the upper cross spring leaf 4 and the lower cross spring leaf 13 p Therefore, the static stiffness is not affected by the negative magnetic stiffness, and the static load-bearing capacity remains unchanged; the negative magnetic stiffness makes the dynamic stiffness K of the isolator D The negative magnetic stiffness obtained by genetic algorithm optimization has the largest linearity near the equilibrium position of the inner magnetic ring 16, while the positive stiffness K p It also remains linear near the equilibrium position of the inner magnetic ring 16, so the total dynamic stiffness K D The linearity is the largest near the equilibrium position of the inner magnetic ring 16, which widens the working displacement range of the vibration isolator. The lower dynamic stiffness makes the natural frequency of the vibration isolator very low, improving the vibration isolation frequency band of the vibration isolator. The linear stiffness of the larger displacement range expands the working displacement range of the vibration isolator, expanding the working application range of the vibration isolator.

[0023] As a preferred embodiment of the present invention, the upper shell 1, upper magnetic ring upper cover 3, upper cross spring leaf 4, upper spring leaf fastener 5, outer magnetic ring shell 6, outer magnetic ring base 7, outer magnetic ring upper cover 9, lower shell 10, lower magnetic ring lower cover 12, lower cross spring leaf 13, lower spring leaf fastener 14, inner magnetic ring base 15 and inner magnetic ring upper cover 17 are all made of hard aluminum alloy material. Hard aluminum alloy has very low magnetic permeability and has little effect on the magnetic field distribution.

[0024] As a preferred embodiment of the present invention, the upper magnetic ring 2, outer magnetic ring 8, lower magnetic ring 11 and inner magnetic ring 16 are all made of neodymium iron boron material, which has a large magnetic energy product; the upper magnetic ring 2, outer magnetic ring 8, lower magnetic ring 11 and inner magnetic ring 16 are N poles along the axial upper side and S poles along the axial lower side to achieve a negative magnetic stiffness effect.

[0025] As a preferred embodiment of the present invention, the bolts and nuts are made of non-magnetic materials. The magnetic permeability of non-magnetic materials is very low and has little effect on the magnetic field distribution.

[0026] As a preferred embodiment of the present invention, the upper magnetic ring 2 and the lower magnetic ring 11 are arranged symmetrically about the outer magnetic ring, and the inner diameter, outer diameter and thickness of the upper magnetic ring 2 are exactly the same as the inner diameter, outer diameter and thickness of the lower magnetic ring 11 to ensure the symmetry of the magnetic force with respect to relative displacement.

Claims

1. A quasi-zero stiffness vibration isolator with a large displacement stroke, characterized by: The invention comprises an upper structure, a lower structure, a middle outer structure, a middle inner structure and a support rod (18); the upper structure comprises an upper shell (1), an upper magnetic ring (2), an upper magnetic ring cover (3), an upper cross spring sheet (4) and an upper spring sheet fastener (5); the upper magnetic ring (2) is installed in an inner groove of the upper shell (1); the upper magnetic ring cover (3) is installed above the upper magnetic ring (2); the upper magnetic ring cover (3) and the upper shell (1) are fixed by bolts; the upper cross spring sheet (4) and the upper spring sheet fastener (5) are fixed by bolts to form an upper spring; the upper spring and the upper shell (1) are fixed by bolts, and the upper spring sheet fastener (5) is kept at the top; the middle outer structure comprises an upper shell (1), an upper magnetic ring (2), an upper magnetic ring cover (3), an upper cross spring sheet (4) and an upper spring sheet fastener (5) are fixed by bolts; the upper spring and the upper shell (1) are fixed by bolts, and the upper spring sheet fastener (5) is kept at the top; The structure comprises an outer magnetic ring shell (6), an outer magnetic ring base (7), an outer magnetic ring (8) and an outer magnetic ring upper cover (9), wherein the outer magnetic ring base (7) is installed in a groove of the outer magnetic ring shell (6), the outer magnetic ring (8) is installed on the outer magnetic ring base (7), the outer magnetic ring upper cover (9) is installed on the outer magnetic ring (8), and the outer magnetic ring upper cover (9) is provided with a through hole, which is coaxially arranged with the through hole of the outer magnetic ring shell (6); the lower structure comprises a lower shell (10), a lower magnetic ring (11), a lower magnetic ring lower cover (12), a lower cross spring sheet (13) and a lower spring sheet fastener (14), the lower magnetic ring (11) is installed in an inner groove of the lower shell (10), the lower magnetic ring lower cover (12) is installed below the lower magnetic ring (11), and The lower magnetic ring lower cover (12) and the lower shell (10) are fixed by bolts, the lower cross spring sheet (13) and the lower spring sheet fastener (14) are fixed by bolts to form a lower spring, and the lower spring and the lower shell (10) are fixed by bolts, and the lower spring sheet fastener (14) is kept at the bottom; the internal structure includes an inner magnetic ring base (15), an inner magnetic ring (16) and an inner magnetic ring upper cover (17), the inner magnetic ring (16) is installed in the inner groove of the inner magnetic ring base (15), the inner magnetic ring upper cover (17) is installed above the inner magnetic ring (16), and the inner magnetic ring upper cover (17) and the inner magnetic ring base (15) are connected and fixed by bolts; the bottom of the upper shell (1) and the lower outer shell (1) are fixed by bolts. The top of the shell (10) and the outer magnetic ring shell (6) are all provided with through holes, and the three are connected and fixed by bolts, so that the upper structure, the middle and outer structure and the lower structure are connected and fixed, the middle part of the support rod (18) matches the central threaded hole of the inner magnetic ring base (15), and the two are fixed by thread connection, the upper part of the support rod (18) matches the threaded hole of the upper spring sheet fastener (5), and the two are fixed by thread connection, the lower part of the support rod (18) matches the threaded hole of the lower spring sheet fastener (14), and the two are fixed by thread connection, and the relative position of the inner magnetic ring (16) is adjusted by rotating the support rod (18) during installation; the lower part of the lower shell (10) is provided with a through hole and connected to the foundation; The upper magnetic ring (2), the lower magnetic ring (11), the outer magnetic ring (8) and the inner magnetic ring (16) constitute a magnetic spring with a large displacement stroke and linear negative stiffness; the upper cross spring sheet (4) and the lower cross spring sheet (13) are connected to the support rod (18) and are respectively connected to the upper shell (1) and the lower shell (10), providing positive stiffness of the vibration isolator, and being connected in parallel with the magnetic spring with a large displacement stroke and linear negative stiffness, thereby reducing the dynamic stiffness of the inner magnetic ring (16) at the equilibrium position.

2. The quasi-zero stiffness vibration isolator with a large displacement stroke according to claim 1, characterized in that: The vibration isolation object is placed on the upper part of the support rod (18). When the vibration isolation object is disturbed in the vertical direction, the disturbance is transmitted to the inner magnetic ring (16) through the support rod (18), causing the inner magnetic ring (16) to undergo a relative displacement z relative to the outer magnetic ring (8), the upper magnetic ring (2) and the lower magnetic ring (11). During this process, the inner magnetic ring (16) is subjected to the magnetic force F of the upper magnetic ring (2), the lower magnetic ring (11) and the outer magnetic ring (8). m Given the geometric dimensions of the inner magnetic ring (16), the outer magnetic ring (8), the upper magnetic ring (2) and the lower magnetic ring (11) and their respective magnetization intensities, the magnetic force F acting on the inner magnetic ring at any position can be calculated according to the equivalent magnetic charge method. m When the magnetization directions of the inner magnetic ring (16), the outer magnetic ring (8), the upper magnetic ring (2) and the lower magnetic ring (11) are all upward, the magnetic force F m It manifests as negative stiffness, that is, the direction of the magnetic force is consistent with the direction of the relative displacement z; then according to the equivalent magnetic charge method, the negative derivative of the magnetic force with respect to the relative displacement z can be obtained, that is, the magnetic negative stiffness K n , the magnetic force F m The Taylor expansion F is performed at the equilibrium position z = 0 of the inner magnetic ring (16). m =-K0z+ε3z 3 +ε5z 5 , where K0 is the negative magnetic stiffness K n The magnitude at the equilibrium position of the inner magnetic ring (16) represents the magnetic force F m The linear part, ε3 and ε5 are the coefficients of the cubic and quintic terms, respectively, which measure the magnetic force F m The nonlinear size of ε3 and ε5 is smaller, and the magnetic force F m The stronger the linearity, the more K0, ε3 and ε5 are related to the geometric dimensions of the inner magnetic ring (16), the outer magnetic ring (8), the upper magnetic ring (2) and the lower magnetic ring (11) and their respective magnetization intensities; the absolute value of the product of the coefficients ε3 and ε5 of the cubic term and the quintic term is used as the objective function f=|ε3·ε5|, the inner diameter of the outer magnetic ring (8), the outer diameter of the outer magnetic ring (8), the thickness of the outer magnetic ring (8), the inner diameter of the upper magnetic ring (2) and the outer diameter of the upper magnetic ring (2) are used as optimization parameters, and the genetic algorithm is used for optimization to minimize the objective function. At this time, the magnetic force F m The linearity is strongest near the equilibrium position of the inner magnetic ring (16), that is, the magnetic force F m The total negative magnetic stiffness K remains unchanged within a displacement range near the equilibrium position of the inner magnetic ring (16); n It will offset part of the positive stiffness K provided by the upper cross spring piece (4) and the lower cross spring piece (13). p , so that the dynamic stiffness K of the vibration isolator near the equilibrium position of the inner magnetic ring (16) D =K p +K n Compared with the dynamic stiffness K′ of the structure without the inner magnetic ring (16), the outer magnetic ring (8), the upper magnetic ring (2) and the lower magnetic ring (11) D =K p Reduce or even approach zero, thereby reducing the resonant frequency of the vibration isolator; the static stiffness K of the structure S Equal to the positive stiffness K provided by the upper cross spring leaf (4) and the lower cross spring leaf (13) p Therefore, the static stiffness is not affected by the negative magnetic stiffness, and the static load-bearing capacity remains unchanged; the negative magnetic stiffness makes the dynamic stiffness K of the isolator D The negative magnetic stiffness obtained by genetic algorithm optimization has the largest linearity near the equilibrium position of the inner magnetic ring (16), while the positive stiffness K p It also remains linear near the equilibrium position of the inner magnetic ring (16), so the total dynamic stiffness K D The linearity is maximum near the equilibrium position of the inner magnetic ring (16), thereby widening the working displacement stroke of the vibration isolator.

3. The quasi-zero stiffness vibration isolator with a large displacement stroke according to claim 1, characterized in that: The upper shell (1), the upper magnetic ring cover (3), the upper cross spring sheet (4), the upper spring sheet fastener (5), the outer magnetic ring shell (6), the outer magnetic ring base (7), the outer magnetic ring upper cover (9), the lower shell (10), the lower magnetic ring lower cover (12), the lower cross spring sheet (13), the lower spring sheet fastener (14), the inner magnetic ring base (15) and the inner magnetic ring cover (17) are all made of hard aluminum alloy material.

4. The quasi-zero stiffness vibration isolator with a large displacement stroke according to claim 1, characterized in that: The upper magnetic ring (2), the outer magnetic ring (8), the lower magnetic ring (11) and the inner magnetic ring (16) are all made of neodymium iron boron material, with an N pole on the upper side along the axial direction and an S pole on the lower side along the axial direction.

5. The quasi-zero stiffness vibration isolator with a large displacement stroke according to claim 1, characterized in that: The bolts and nuts are made of non-magnetic conductive materials.

6. The quasi-zero stiffness vibration isolator with a large displacement stroke according to claim 1, characterized in that: The upper magnetic ring (2) and the lower magnetic ring (11) are arranged symmetrically up and down with respect to the outer magnetic ring, and the inner diameter, outer diameter and thickness of the upper magnetic ring (2) are completely the same as those of the lower magnetic ring (11).

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