CN111734775A - Large load-bearing ultra-low frequency air spring isolator based on negative stiffness magnetic spring - Google Patents

Abstract

The large-load ultra-low frequency air spring vibration isolator based on the negative stiffness magnetic spring belongs to the field of precision vibration isolation technology, including a dual-chamber air spring vibration isolator and a negative stiffness magnetic spring. The negative stiffness magnetic spring is coaxially nested in the dual-chamber air spring. In the main air chamber of the spring vibration isolator, an annular rubber pad is arranged at the bottom of the main air chamber, and 2 to 10 orifices are evenly arranged between the main air chamber and the additional air chamber; The upper moving magnetic ring and the lower moving magnetic ring, which are arranged symmetrically about the axial height of the fixed magnetic ring, are formed by coaxial nesting, and the upper moving magnetic ring and the lower moving magnetic ring are reversely magnetized in the axial direction; , large damping coefficient, high integration, can achieve low frequency/ultra low frequency vibration isolation effect of precision instruments and equipment.

Description

Large load-bearing ultra-low frequency air spring isolator based on negative stiffness magnetic spring

technical field

The invention belongs to the technical field of precision vibration damping, in particular to a large-loading ultra-low frequency air spring vibration isolator based on a negative stiffness magnetic spring.

Background technique

In the process of installation, testing and experimentation of precision instruments and equipment, low-frequency vibration interference in the environment has become one of the key issues affecting research results. Equipping precision instruments and equipment with large-load air spring vibration isolators has gradually become a large-scale ultra-precision engineering field. The main technical means of environmental micro-vibration, but the research on air spring vibration isolators still has the following problems:

(1) The natural frequency of the air spring vibration isolator is high, and it cannot suppress the low frequency/ultra low frequency vibration interference in the environment. Existing air spring vibration isolators can achieve large load and medium and high frequency vibration suppression effects, but to achieve low frequency/ultra low frequency vibration suppression requires increasing the volume of the chamber, which not only increases the manufacturing cost and space, but also increases the volume of the chamber. Its low-frequency vibration suppression effect is less obvious. Therefore, in actual use, it is generally difficult for air spring vibration isolators to isolate vibrations below 1Hz.

(2) The system damping of the air spring vibration isolator is small, resulting in a long stable adjustment time under impact disturbance and a high resonance peak value. The air spring vibration isolator is a non-contact spring that fills the flexible membrane with compressed gas and uses the compressibility of the gas to achieve elastic support. There is no mechanical friction. The structural damping of the flexible membrane is the main factor of the air spring vibration isolator. The damping source, the damping coefficient is small, resulting in slow vibration energy attenuation, long system stability adjustment time and high resonance peak under the excitation of shock disturbance.

(3) The air spring vibration isolator with parallel magnetic negative stiffness structure has low integration degree. The parallel connection of the magnetic negative stiffness structure and the air spring isolator can reduce the natural frequency under the condition of ensuring the large load of the air spring isolator, so as to achieve the high-load low-frequency/ultra-low frequency vibration isolation effect. However, the existing low-frequency vibration isolator composed of a cubic permanent magnet negative stiffness structure and an air spring isolator in parallel has a large volume and low system integration, and the stiffness value of the negative stiffness structure is affected by the floating height of the air spring isolator.

(4) The air spring vibration isolator with parallel magnetic negative stiffness structure has no corresponding protection measures for impact disturbance excitation. Large-scale impact perturbation excitation leads to rigid collision between the moving magnet and the fixed magnet of the magnetically negative rigidity structure, and between the moving magnet and or the fixed part of the fixed magnet, which is easy to cause damage or breakage of the magnet.

Patent No. CN201310142491.9 discloses a positive and negative stiffness parallel shock absorber. In the technical scheme, the magnetic negative stiffness structure is coaxially installed in the air spring vibration isolator chamber to form a positive and negative stiffness parallel shock absorber. The magnetic negative stiffness structure is composed of two coaxial magnetic rings that are reversely magnetized in the radial direction, and the structure is compact. , and do not need to consider the effect of the air spring isolator flying height on the negative stiffness magnetic spring stiffness value. The technical solution is characterized in that: 1) the magnetic negative stiffness structure is a non-contact action mode, which does not improve the damping characteristics of the air spring vibration isolator; 2) the magnetic negative stiffness structure has no corresponding protection measures under impact disturbance excitation.

Patent numbers CN201610914596.5 and CN201610914512.8 disclose a magnetic negative stiffness structure to reduce the natural frequency of an air spring vibration isolator. The magnetic negative stiffness structure consists of three cubic permanent magnets with the same magnetization direction and arranged in an array of equal vertical gaps The stiffness value can be adjusted by changing the permanent magnet gap. The features of this technical solution are: 1) It is suitable for air spring isolators with a small floating height. For a large load-bearing air spring isolator, a larger floating height will increase the permanent magnet gap, which will lead to negative magnetic stiffness. The stiffness value of the structure is very small, and the effect on reducing the natural frequency of the air spring isolator is not obvious; 2) The structural damping of the elastic membrane is small; 3) The air spring vibration isolator and the magnetic negative stiffness structure are separately installed and arranged, and the system is integrated. 4) Under the excitation of shock disturbance, there is no corresponding protective measures for the structure with negative magnetic stiffness.

Patent No. CN201810853079.0 discloses a quasi-zero stiffness vibration isolator with positive and negative stiffness in parallel. The technical scheme uses axially magnetized coaxial double magnetic rings to form a magnetic negative stiffness structure, and the axial magnetization of the magnetic ring is convenient; the magnetic ring gap is perpendicular to the direction of the up-and-down motion of the positive stiffness support element, so there is no need to consider the positive stiffness support The effect of the flying height of the element on the stiffness value of the magnetically negative stiffness structure. The technical scheme is characterized in that: 1) the magnetic negative stiffness structure is a non-contact mode of action, which does not improve the damping characteristics of the air spring isolator; 2) the magnetic negative stiffness structure is evenly distributed on the left and right sides of the positive stiffness support element, and the system Low integration and large volume.

To sum up, how to provide a magnetic negative stiffness structure with high integration, large damping, and not affected by the floating height of the positive stiffness support element through the vibration isolation structure and principle innovation to offset the positive stiffness of the large load air spring vibration isolator It is of great significance to further improve the low-frequency vibration isolation performance of the micro-vibration isolation platform, increase the structural damping, and rapidly attenuate the vibration energy.

SUMMARY OF THE INVENTION

The purpose of the present invention is that the high natural frequency of the large-loaded air spring vibration isolator cannot meet the low frequency/ultra low frequency vibration isolation requirements of precision instruments and equipment, and the small damping coefficient leads to long stable adjustment time under impact disturbance, high resonance peak value, and shock disturbance excitation. Due to the problem that there is no corresponding protection measures for the lower negative stiffness magnetic spring, a large-load ultra-low frequency air spring isolator based on the negative-stiffness magnetic spring is proposed, which can realize the ultra-low frequency vibration isolation effect under large load conditions. , so as to effectively isolate the environmental micro-vibration interference in high, medium and low frequency bands, improve the vibration isolation level of the anti-micro-vibration laboratory, and ensure that various ultra-precision instruments and equipment work in the optimal environment, while the system's orifice damping and eddy current Damping helps to accelerate vibration energy decay and reduce resonance peaks.

The technical solution of the present invention is:

A large load-bearing ultra-low frequency air spring vibration isolator based on a negative stiffness magnetic spring, including an air spring vibration isolator and a negative stiffness magnetic spring, the negative stiffness magnetic spring is coaxially nested in the air spring vibration isolator, and the overall structure Axisymmetric, the air spring vibration isolator includes a main air chamber, an elastic membrane, an inner pressure ring and an outer pressure ring. The outer pressure ring presses and fixes the outer end of the annular elastic membrane on the main air chamber, and the top end of the inner pressure ring Support the vibration isolation load; the air spring vibration isolator also includes an additional air chamber, the additional air chamber is fixedly installed directly below the main air chamber, the side wall of the additional air chamber is provided with air inlet holes, and the main air chamber and the additional air chamber are provided with air inlet holes. 2 to 10 orifices are evenly arranged between the main air chambers, the material of the main air chamber is non-magnetic or weakly magnetically conductive aluminum alloy, titanium alloy or austenitic stainless steel, and an annular rubber pad is arranged at the bottom of the main air chamber; the negative stiffness The magnetic spring includes a moving magnetic ring mounting member, a moving magnetic ring and a fixed magnetic ring that are coaxially nested from the axis to the outside along the radius. The material of the moving magnetic ring mounting member is non-magnetic or weakly magnetically conductive aluminum alloy, titanium alloy or Austenitic stainless steel, the moving magnetic ring includes an upper moving magnetic ring and a lower moving magnetic ring. The upper moving magnetic ring and the lower moving magnetic ring are arranged symmetrically about the axial height of the fixed magnetic ring. Axially reverse magnetized and fixedly connected to the outer wall of the moving magnet ring mounting piece, the inner pressure ring presses and fixes the inner end of the annular elastic film on the top of the moving magnet ring mounting piece, and the moving magnet ring and the fixed magnet ring are radially provided with a gap , the fixed magnetic ring is magnetized in the radial direction and fixed on the inner wall of the main air chamber coaxially. There is a repulsion effect between the fixed magnetic ring and the upper moving magnetic ring, and a repulsive force between the fixed magnetic ring and the lower moving magnetic ring.

Preferably, the stationary magnetic ring is magnetized radially toward the axial center, and the upper moving magnetic ring is magnetized axially downward, or the stationary magnetic ring is magnetized outwardly from the axial center along the radius, and the upper moving magnetic ring is magnetized axially upward.

Preferably, the fixed magnetic ring, the upper moving magnetic ring and the lower moving magnetic ring are permanent magnets or electromagnets.

Preferably, the shape of the orifice is a circle, an ellipse or a polygon.

Preferably, the diameter of the circumscribed circle of the orifice is 1 mm˜10 mm.

Preferably, the volume of the additional air chamber is not greater than 3 times the volume of the main air chamber.

Preferably, the elastic film is vulcanized from a rubber material and nylon cords or polyester cords.

Preferably, the rubber pad is vulcanized from a rubber material and nylon cords or polyester cords.

The technical innovation of the present invention and the good effect produced are:

(1) The technical solution can realize the large load and near-zero frequency vibration isolation effect of the air spring vibration isolator. On the one hand, the present invention reduces the stiffness value and natural frequency of the air spring vibration isolator by connecting additional air chambers in series; Isolate the micro-vibration interference of the whole frequency band in the environment where the ultra-precision instruments and equipment are located. This is one of the innovative points of the present invention which is different from the prior art.

(2) The orifice damping and eddy current damping produced by the present invention can effectively accelerate the attenuation of vibration energy and shorten the system stabilization time. In the present invention, orifices of different shapes, sizes and numbers are arranged between the main air chamber and the additional air chamber to introduce the damping of the orifice and increase the damping of the system; The eddy current damping generated inside can effectively restrain the movement of the moving magnetic ring relative to the fixed magnetic ring, quickly attenuate the vibration energy, and shorten the system stabilization time. This is the second innovative point of the present invention which is different from the prior art.

(3) The technical solution adopts the method of nesting the coaxial magnetic ring negative stiffness magnetic spring to avoid the influence of the floating height of the air spring vibration isolator on the negative stiffness value, and at the same time realizes the characteristics of high integration. The negative stiffness magnetic spring is composed of a radially magnetized fixed magnetic ring and an axially magnetized moving magnetic ring. The effect of height on the stiffness value of the negative stiffness magnetic spring; the negative stiffness magnetic spring is nested and installed in the main air chamber of the air spring isolator to improve the integration of the system. This is the third innovative point of the present invention which is different from the prior art.

(4) The present invention can effectively avoid rigid collision under impact disturbance excitation. The invention provides a rubber pad at the bottom of the main air chamber of the air spring vibration isolator as a protection measure for the magnetic spring with negative stiffness, which can effectively avoid the phenomenon that the magnetic ring is damaged due to rigid collision between the moving magnetic ring and the bottom of the main air chamber under impact disturbance excitation.

Description of drawings

Fig. 1 is a three-dimensional cross-sectional schematic diagram of a large-load ultra-low frequency air spring isolator based on a negative stiffness magnetic spring;

Fig. 2 is the front sectional schematic diagram of the large-load ultra-low frequency air spring isolator based on the negative stiffness magnetic spring;

3 is a schematic diagram of the magnetization direction of the magnetic ring in the negative stiffness magnetic spring;

Figure 4 is the force analysis diagram at the equilibrium position of the negative stiffness magnetic spring;

Figure 5 is the force analysis diagram of the negative stiffness magnetic spring when it moves upwards from the equilibrium position;

Figure 6 is the force analysis diagram of the negative stiffness magnetic spring when it moves downward from the equilibrium position.

Description of part number in the picture: 1 air inlet, 2 rubber pad, 3 main air chamber, 4 additional air chamber, 5 elastic membrane, 6 inner pressure ring, 7 outer pressure ring, 8 fixed magnetic ring, 9 throttle hole, 10 Moving magnet ring, 10a upper moving magnet ring, 10b lower moving magnet ring, 11 moving magnet ring mounting parts.

Detailed ways

The specific embodiments of the present invention will be described in detail below with reference to the accompanying drawings.

A large load-bearing ultra-low frequency air spring vibration isolator based on a negative stiffness magnetic spring, including an air spring vibration isolator and a negative stiffness magnetic spring, the negative stiffness magnetic spring is coaxially nested in the air spring vibration isolator, and the overall structure Axisymmetric, the air spring vibration isolator includes a main air chamber 3, an elastic membrane 5, an inner pressure ring 6 and an outer pressure ring 7, and the outer pressure ring 7 presses and fixes the outer end of the annular elastic membrane 5 in the main air chamber 3, the top end of the inner pressure ring 6 supports the vibration isolation load; the air spring vibration isolator also includes an additional air chamber 4, the additional air chamber 4 is fixedly installed directly below the main air chamber 3, and the side wall of the additional air chamber 4 is provided Air inlet 1, 2 to 10 throttle holes 9 are evenly arranged between the main air chamber 3 and the additional air chamber 4, the material of the main air chamber 3 is non-magnetic or weakly magnetically conductive aluminum alloy, titanium alloy or austenitic The body is made of stainless steel, and the bottom of the main air chamber 3 is provided with an annular rubber pad 2; the negative stiffness magnetic spring includes a moving magnetic ring mounting member 11, a moving magnetic ring 10 and a fixed magnetic ring 8 that are coaxially nested outward along the radius from the axis. The material of the moving magnetic ring mounting member 11 is non-magnetic or weakly magnetically conductive aluminum alloy, titanium alloy or austenitic stainless steel. The upper moving magnet ring 10a and the lower moving magnet ring 10b are axially reversely magnetized and fixedly connected to the outer wall of the moving magnet ring mounting member 11, and the internal pressure The ring 6 presses and fixes the inner end of the annular elastic film 5 on the top of the moving magnet ring mounting member 11, the moving magnet ring 10 and the fixed magnet ring 8 are radially provided with a gap, and the fixed magnet ring 8 is magnetized along the radial direction and fixed coaxially. Installed on the inner wall of the main air chamber 3, there is a repulsive force between the fixed magnetic ring 8 and the upper moving magnetic ring 10a, and a repulsive force between the fixed magnetic ring 8 and the lower moving magnetic ring 10b.

As a specific embodiment, the fixed magnetic ring 8 is magnetized along the radius to the axial center, the upper moving magnetic ring 10a is magnetized downward along the axial direction, or the fixed magnetic ring 8 is magnetized outward along the radius from the axial center, and the upper moving magnet is magnetized downward. The ring 10a is magnetized upward in the axial direction.

As a specific embodiment, the fixed magnetic ring 8 , the upper moving magnetic ring 10 a and the lower moving magnetic ring 10 b are permanent magnets or electromagnets.

As a specific embodiment, the shape of the orifice 9 is a circle, an ellipse or a polygon.

As a specific embodiment, the diameter of the circumscribed circle of the orifice 9 is 1 mm˜10 mm.

As a specific implementation manner, the volume of the additional air chamber 4 is not greater than three times the volume of the main air chamber 3 .

As a specific embodiment, the elastic film 5 is vulcanized from a rubber material and nylon cords or polyester cords.

As a specific embodiment, the rubber pad 2 is vulcanized from a rubber material and nylon cords or polyester cords.

An embodiment of the present invention is given below with reference to FIGS. 1 to 3 .

1 and 2 are a three-dimensional schematic cross-sectional view and a front cross-sectional view of the positive and negative stiffness parallel vibration isolator provided by the present invention, respectively, and FIG. 3 is a schematic diagram of the magnetization direction of the magnetic ring in the negative stiffness magnetic spring. As shown in FIG. 1 and FIG. 2 , the large-load ultra-low frequency air spring vibration isolator based on the negative stiffness magnetic spring provided by the present invention includes an air spring vibration isolator and a negative stiffness magnetic spring, and an air spring vibration isolator and a negative stiffness magnetic spring. The springs are installed coaxially and arranged in parallel, and the whole is axisymmetric. The air spring vibration isolator includes a main air chamber 3, an additional air chamber 4, an elastic membrane 5, an inner pressure ring 6 and an outer pressure ring 7. The main air chamber 3 and the additional air chamber 4 are made of 304 stainless steel, and the volume of the additional air chamber 4 Three times the volume of the main air chamber 3, the positive stiffness generated by the air spring isolator is reduced by 75% and the natural frequency is reduced by 50%, without changing the bearing capacity of the air spring isolator. The elastic film 5 and the outer pressure ring 7 are annular structures, the inner pressure ring 6 is a cylindrical structure, the elastic film 5 is vulcanized from rubber and nylon cords, and the material of the inner pressure ring 6 and the outer pressure ring 7 is light aluminum alloy . The top of the inner pressure ring 6 supports the vibration isolation load, the bottom of the inner pressure ring 6 presses and fixes the inner end of the elastic film 5 on the top of the moving magnet ring mounting member 11, and the outer pressure ring 7 presses and fixes the outer end of the elastic film 5 on the top of the moving magnet ring mounting member 11. on the side wall of the main air chamber 3. The bottom of the main air chamber 3 is provided with a rubber pad 2 with a thickness of 2 mm, which is vulcanized from rubber and nylon cords to prevent the moving magnetic ring 10 of the negative stiffness magnetic spring 1 from colliding with the main air chamber 3 due to large vibration displacement. . The bottom of the main air chamber 3 and the top of the additional air chamber 4 are evenly set with 6 circular holes with a diameter of 40 mm along a circle with a diameter of 40 mm. The top of the additional air chamber 4 is set with a diameter equal to the outer diameter of the main air chamber 3. The main air chamber 3 is fixed coaxially in the circular groove at the top of the additional air chamber 4, and ensures that the bottom of the main air chamber 3 is opposite to the circular hole at the top of the chamber of the additional air chamber 4, as a dual-chamber air spring The orifice 9 of the vibration isolator is used to increase the system damping, reduce the resonance peak value, and shorten the stabilization time. A circular air inlet 1 is set on the side wall of the additional air chamber 4. The air inlet 1 is passed through the air supply system with clean compressed gas to support the vibration isolation load. The working air pressure of the air spring vibration isolator is 0.3MPa, and the floating height is 10mm. .

The negative stiffness magnetic spring includes a fixed magnetic ring 8, a moving magnetic ring mounting member 11 and a moving magnetic ring 10. The moving magnetic ring mounting member 11 is made of 304 stainless steel, and the moving magnetic ring 10 includes an upper moving magnetic ring 10a and a lower moving magnetic ring 10b. , the fixed magnetic ring 8 is magnetized toward the axis along the radius, the upper moving magnetic ring 10a is magnetized downward along the axial direction, and the lower moving magnetic ring 10b is magnetized upward along the axial direction, and the magnetization direction of the magnetic ring is shown by the arrow in Figure 3; The outer diameter of the ring 8 is equal to the inner diameter of the main air chamber 3, and the inner diameter is larger than the outer diameter of the upper moving magnetic ring 10a and the lower moving magnetic ring 10b. Equally, the fixed magnetic ring 8 is coaxially fixed on the inner wall of the main air chamber 3, the upper moving magnetic ring 10a and the lower moving magnetic ring 10b are coaxially nested and fixed on the outer wall of the moving magnetic ring mounting member 11, and the bottom of the upper moving magnetic ring 10a It is connected to the top of the lower moving magnetic ring 10b, and the bottom of the upper moving magnetic ring 10a is 10mm lower than the center of the axial height of the fixed magnetic ring 8. The material of the magnetic ring is N50 grade NdFeB, the residual magnetic induction intensity is 1.43T, and the relative magnetic permeability is 1.03. When the air spring vibration isolator is inflated to 0.3MPa, the elastic membrane 5 expands under the action of compressed air, and the inner pressure ring 6 drives the moving magnetic ring 10 to move upward in the axial direction by 10 mm through the moving magnetic ring mounting member 11, so that the fixed magnetic ring 8 The center of the axial height is the same height as the bottom of the upper moving magnetic ring 10a and the top of the lower moving magnetic ring 10b. Under the interference of external vibration, the upper moving magnetic ring 10a and the lower moving magnetic ring 10b move relative to the fixed magnetic ring 8, and the magnetic field lines generated by the moving magnetic ring 10 cut the main air chamber 3, thereby generating eddy currents in the main air chamber 3. The damping prevents the moving magnetic ring 10 from moving relative to the fixed magnetic ring 8, accelerates vibration attenuation, and shortens the stable adjustment time of the vibration isolation system.

4 is the force analysis diagram at the equilibrium position of the negative stiffness magnetic spring, the upper moving magnetic ring 10a and the lower moving magnetic ring 10b are in the magnetic field excited by the fixed magnetic ring 8, and the magnetic force on the negative stiffness magnetic spring is the upper moving magnetic ring 10a and the lower moving magnetic ring 10b are subjected to the sum of the repulsive forces f ₁ and f ₂ of the fixed magnetic ring 8 . At the equilibrium position, the top of the upper moving magnetic ring 10a, the bottom of the lower moving magnetic ring 10b and the axial height center of the fixed magnetic ring 8 are on the same horizontal line, so the magnetic forces f ₁ and f ₂ are both directed from the fixed magnetic ring 8 to the moving magnet along the horizontal direction. Ring, due to the symmetry of the negative stiffness magnetic spring structure, the magnetic force on the negative stiffness magnetic spring at the equilibrium position is 0.

Fig. 5 is the force analysis diagram when the negative stiffness magnetic spring deviates from the equilibrium position and moves upward. The top of the upper moving magnetic ring 10a and the bottom of the lower moving magnetic ring 10b are higher than the axial height center of the fixed magnetic ring 8, and f ₁ is along the fixed magnetic ring. 8 and the center line of the upper moving magnetic ring 10a point to the axis, and f ₂ points to the axis along the center line of the fixed magnetic ring 8 and the lower moving magnetic ring 10b. Due to the symmetry of the negative stiffness magnetic spring structure, f ₁ and f ₂ are along the axis. The radial component forces cancel each other out, and the superimposed axial component forces force the negative stiffness magnetic spring to move upwards in the axial direction away from the equilibrium position.

Fig. 6 is the force analysis diagram when the negative stiffness magnetic spring deviates from the equilibrium position and moves downward. The top of the upper moving magnetic ring 10a and the bottom of the lower moving magnetic ring 10b are lower than the axial height center of the fixed magnetic ring 8, and f ₁ is along the fixed magnetic The line connecting the center of the ring 8 and the upper moving magnetic ring 10a is far away from the axis, and f ₂ is far away from the axis along the center line connecting the fixed magnetic ring 8 and the lower moving magnetic ring 10b. Due to the symmetry of the negative stiffness magnetic spring structure, f ₁ and f ₂ The component forces along the radial direction cancel each other, and the axial component forces superimposed on each other force the negative stiffness magnetic spring to move downward in the axial direction away from the equilibrium position.

Claims (8)

1. A large-loaded ultra-low frequency air spring vibration isolator based on a negative stiffness magnetic spring, comprising an air spring vibration isolator and a negative stiffness magnetic spring, the negative stiffness magnetic spring being coaxially nested in the air spring vibration isolator, The overall structure is axisymmetric, and the air spring vibration isolator includes a main air chamber (3), an elastic membrane (5), an inner pressure ring (6) and an outer pressure ring (7), and the outer pressure ring (7) elastically The outer end of the membrane (5) is pressed and fixed on the main air chamber (3), and the top end of the inner pressure ring (6) supports the vibration isolation load; it is characterized in that: the air spring vibration isolator further comprises an additional air chamber (4) , the additional air chamber (4) is fixedly installed directly below the main air chamber (3), the side wall of the additional air chamber (4) is provided with air inlet holes (1), the main air chamber (3) and the additional air chamber (4) 2 to 10 orifices (9) are evenly arranged between them, the material of the main air chamber (3) is non-magnetic or weakly magnetically conductive aluminum alloy, titanium alloy or austenitic stainless steel, and the material of the main air chamber (3) A ring-shaped rubber pad (2) is arranged at the bottom; the negative stiffness magnetic spring includes a moving magnet ring mounting member (11), a moving magnet ring (10) and a fixed magnet ring (8) that are coaxially nested from the axis to the outside along the radius, The material of the moving magnetic ring mounting member (11) is non-magnetic or weakly magnetically conductive aluminum alloy, titanium alloy or austenitic stainless steel, and the moving magnetic ring (10) includes an upper moving magnetic ring (10a) and a lower moving magnetic ring ( 10b), the upper moving magnetic ring (10a) and the lower moving magnetic ring (10b) are symmetrically arranged with respect to the axial height of the fixed magnetic ring (8), and the upper moving magnetic ring (10a) and the lower moving magnetic ring (10b) are arranged along the axis It is magnetized in the reverse direction and fixedly connected to the outer wall of the moving magnet ring mounting member (11), and the inner pressure ring (6) presses and fixes the inner end of the annular elastic film (5) on the top of the moving magnet ring mounting member (11). The ring (10) and the fixed magnetic ring (8) are radially provided with a gap, and the fixed magnetic ring (8) is magnetized in the radial direction and is coaxially fixed on the inner wall of the main air chamber (3). The fixed magnetic ring (8) There is a repulsive force between the upper moving magnetic ring (10a) and the fixed magnetic ring (8) and the lower moving magnetic ring (10b). 2. The large-loaded ultra-low frequency air spring vibration isolator based on negative stiffness magnetic spring according to claim 1, characterized in that: the fixed magnetic ring (8) is magnetized to the axial center along the radius, and the upper moving magnetic ring (10a) ) is magnetized downward in the axial direction, or the fixed magnetic ring (8) is magnetized outward along the radius from the axis, and the upper moving magnetic ring (10a) is magnetized upward in the axial direction. 3. The large-loaded ultra-low frequency air spring vibration isolator based on a negative stiffness magnetic spring according to claim 1, characterized in that: the fixed magnetic ring (8), the upper moving magnetic ring (10a) and the lower moving magnetic ring (10b) is a permanent magnet or an electromagnet. 4 . The large-loaded ultra-low frequency air spring vibration isolator based on a negative stiffness magnetic spring according to claim 1 , wherein the shape of the orifice ( 9 ) is a circle, an ellipse or a polygon. 5 . 5. The large-loaded ultra-low frequency air spring vibration isolator based on a negative stiffness magnetic spring according to claim 1 or 4, characterized in that: the diameter of the circumscribed circle of the orifice (9) is 1 mm to 10 mm. 6. The large-loaded ultra-low frequency air spring vibration isolator based on negative stiffness magnetic spring according to claim 1, characterized in that: the volume of the additional air chamber (4) is not greater than 3 times the volume of the main air chamber (3). times. 7. The large-loaded ultra-low frequency air spring vibration isolator based on a negative stiffness magnetic spring according to claim 1, wherein the elastic film (5) is vulcanized from a rubber material and a nylon cord or a polyester cord. . 8. The large load-bearing ultra-low frequency air spring vibration isolator based on a negative stiffness magnetic spring according to claim 1, wherein the rubber pad (2) is vulcanized from a rubber material and a nylon cord or a polyester cord .

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