CN111734775B - Large-load ultralow-frequency air spring vibration isolator based on negative-stiffness magnetic spring - Google Patents
Large-load ultralow-frequency air spring vibration isolator based on negative-stiffness magnetic spring Download PDFInfo
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- CN111734775B CN111734775B CN202010605236.3A CN202010605236A CN111734775B CN 111734775 B CN111734775 B CN 111734775B CN 202010605236 A CN202010605236 A CN 202010605236A CN 111734775 B CN111734775 B CN 111734775B
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
- F16F—SPRINGS; SHOCK-ABSORBERS; MEANS FOR DAMPING VIBRATION
- F16F13/00—Units comprising springs of the non-fluid type as well as vibration-dampers, shock-absorbers, or fluid springs
- F16F13/002—Units comprising springs of the non-fluid type as well as vibration-dampers, shock-absorbers, or fluid springs comprising at least one fluid spring
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
- F16F—SPRINGS; SHOCK-ABSORBERS; MEANS FOR DAMPING VIBRATION
- F16F6/00—Magnetic springs; Fluid magnetic springs, i.e. magnetic spring combined with a fluid
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
- F16F—SPRINGS; SHOCK-ABSORBERS; MEANS FOR DAMPING VIBRATION
- F16F9/00—Springs, vibration-dampers, shock-absorbers, or similarly-constructed movement-dampers using a fluid or the equivalent as damping medium
- F16F9/02—Springs, vibration-dampers, shock-absorbers, or similarly-constructed movement-dampers using a fluid or the equivalent as damping medium using gas only or vacuum
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
- F16F—SPRINGS; SHOCK-ABSORBERS; MEANS FOR DAMPING VIBRATION
- F16F9/00—Springs, vibration-dampers, shock-absorbers, or similarly-constructed movement-dampers using a fluid or the equivalent as damping medium
- F16F9/32—Details
- F16F9/34—Special valve constructions; Shape or construction of throttling passages
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
- F16F—SPRINGS; SHOCK-ABSORBERS; MEANS FOR DAMPING VIBRATION
- F16F2222/00—Special physical effects, e.g. nature of damping effects
- F16F2222/12—Fluid damping
- F16F2222/126—Fluid damping using gases
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
- F16F—SPRINGS; SHOCK-ABSORBERS; MEANS FOR DAMPING VIBRATION
- F16F2228/00—Functional characteristics, e.g. variability, frequency-dependence
- F16F2228/06—Stiffness
- F16F2228/063—Negative stiffness
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Abstract
The large-bearing ultralow-frequency air spring vibration isolator based on negative stiffness magnetic springs belongs to the technical field of precision vibration isolation, and comprises a double-chamber air spring vibration isolator and negative stiffness magnetic springs, wherein the negative stiffness magnetic springs are coaxially nested in a main air chamber of the double-chamber air spring vibration isolator, an annular rubber pad is arranged at the bottom of the main air chamber, and 2-10 throttling holes are uniformly formed between the main air chamber and an additional air chamber; the negative stiffness magnetic spring is formed by coaxially nesting a fixed magnetic ring magnetized along the radial direction, an upper movable magnetic ring and a lower movable magnetic ring which are arranged in a central symmetry mode relative to the axial height of the fixed magnetic ring, and the upper movable magnetic ring and the lower movable magnetic ring are magnetized reversely along the axial direction; the invention has low natural frequency, large damping coefficient and high integration level, and can realize the low-frequency/ultra-low-frequency vibration isolation effect of precise instruments and equipment.
Description
Technical Field
The invention belongs to the technical field of precise vibration reduction, and particularly relates to a large-bearing ultralow-frequency air spring vibration isolator based on negative-stiffness magnetic springs.
Background
In the processes of adjustment, test and experiment of precision instruments and equipment, low-frequency vibration interference in the environment becomes one of key problems influencing the research effect, and the equipping of a large-load-bearing air spring vibration isolator for the precision instruments and equipment gradually becomes a main technical means for inhibiting environmental micro-vibration in the field of large-scale ultra-precision engineering, but the following problems still exist in the research of the air spring vibration isolator:
(1) the natural frequency of the air spring vibration isolator is high, and the low-frequency/ultralow-frequency vibration interference in the environment cannot be inhibited. The existing air spring vibration isolator can achieve large bearing and medium-high frequency vibration suppression effects, but the volume of a cavity needs to be increased for achieving low-frequency/ultralow-frequency vibration suppression, so that the manufacturing cost and the using space are increased, and the low-frequency vibration suppression effect is less obvious along with the increase of the volume of the cavity, so that the air spring vibration isolator is difficult to isolate vibration below 1Hz in actual use.
(2) The system damping of the air spring vibration isolator is small, so that the stable adjustment time under the impact disturbance is long, and the resonance peak value is high. The air spring vibration isolator is a non-contact spring which is characterized in that compressed gas is filled into a flexible membrane, elastic support is realized by utilizing the compressibility of the gas, mechanical friction does not exist, the structural damping of the flexible membrane is used as a main damping source of the air spring vibration isolator, the damping coefficient is small, so that the vibration energy attenuation is slow under the excitation of impact disturbance, the system stability adjustment time is long, and the resonance peak value is high.
(3) The integration level of the air spring vibration isolator with the parallel magnetic negative stiffness structure is low. The magnetic negative stiffness structure is connected with the air spring vibration isolator in parallel, so that the inherent frequency can be reduced under the condition of ensuring the large bearing of the air spring vibration isolator, and the low-frequency/ultralow-frequency vibration isolation effect with large bearing is realized. However, the existing low-frequency vibration isolator formed by connecting the cubic permanent magnet negative stiffness structure and the air spring vibration isolator in parallel is large in size and low in system integration level, and the stiffness value of the negative stiffness structure is influenced by the floating height of the air spring vibration isolator.
(4) The air spring vibration isolator with the parallel magnetic negative stiffness structure has no corresponding protection measure on impact disturbance excitation. The large-amplitude impact disturbance excitation causes rigid collision between the moving magnet and the fixed magnet of the magnetic negative stiffness structure, and between the moving magnet and the fixed magnet fixing piece, so that the magnet is easily damaged or broken.
Patent No. CN201310142491.9 discloses a positive and negative stiffness parallel damper. According to the technical scheme, the magnetic negative stiffness structure is coaxially arranged in the air spring vibration isolator cavity to form the positive and negative stiffness parallel connection vibration absorber, the magnetic negative stiffness structure is formed by two coaxial magnetic rings magnetized reversely along the radial direction, the structure is compact, and the influence of the floating height of the air spring vibration isolator on the stiffness value of the negative stiffness magnetic spring is not required to be considered. The technical scheme is characterized in that: 1) the magnetic negative stiffness structure is in a non-contact action mode, and the damping characteristic of the air spring vibration isolator is not improved; 2) under the excitation of impact disturbance, the magnetic negative stiffness structure has no corresponding protective measures.
Patent numbers CN201610914596.5 and CN201610914512.8 disclose a magnetic negative stiffness structure to reduce the natural frequency of the air spring vibration isolator, the magnetic negative stiffness structure is composed of three cubic permanent magnets with the same magnetization direction and arranged along a vertical equal gap array, and the stiffness value can be adjusted by changing the gap of the permanent magnets. The technical scheme is characterized in that: 1) the large floating height can increase the gap of the permanent magnet for the large-load air spring vibration isolator, so that the rigidity value of the magnetic negative rigidity structure is very small, and the effect of reducing the natural frequency of the air spring vibration 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 arranged in a split manner, so that the system integration level is low and the volume is large; 4) under the excitation of impact disturbance, the magnetic negative stiffness structure has no corresponding protective measures.
Patent No. CN201810853079.0 discloses a quasi-zero stiffness vibration isolator with parallel positive and negative stiffness. According to the technical scheme, the magnetic negative stiffness structure is formed by the coaxial double magnetic rings magnetized in the axial direction, and the magnetic rings are convenient to axially magnetize and process; the magnetic ring gap is vertical to the rising and falling movement direction of the positive rigidity supporting element, so that the influence of the floating height of the positive rigidity supporting element on the rigidity value of the magnetic negative rigidity structure is not required to be considered. The technical scheme is characterized in that: 1) the magnetic negative stiffness structure is in a non-contact action mode, and the damping characteristic of the air spring vibration isolator is not improved; 2) the magnetic negative stiffness structures are uniformly distributed on the left side and the right side of the positive stiffness supporting element, and the system is low in integration level and large in size.
In conclusion, through the innovation of the vibration isolation structure and the principle, the magnetic negative stiffness structure which has high integration degree and large damping and is not influenced by the floating height of the positive stiffness supporting element is provided to offset the positive stiffness value of the large-bearing air spring vibration isolator, so that the magnetic negative stiffness structure has great significance for further improving the low-frequency vibration isolation performance of the micro-vibration isolation platform, increasing the structural damping and quickly attenuating vibration energy.
Disclosure of Invention
The invention aims to solve the problems that the inherent frequency of a large-bearing air spring vibration isolator is high and cannot meet the low-frequency/ultralow-frequency vibration isolation requirement of precision instruments and equipment, the stable adjustment time under impact disturbance is long due to small damping coefficient, the resonance peak value is high, and no corresponding protective measures are provided for a negative-stiffness magnetic spring under the excitation of the impact disturbance.
The technical solution of the invention is as follows:
a large-bearing ultralow-frequency air spring vibration isolator based on negative stiffness magnetic springs comprises an air spring vibration isolator and negative stiffness magnetic springs, wherein the negative stiffness magnetic springs are coaxially nested in the air spring vibration isolator, the overall structure is in axial symmetry, the air spring vibration isolator comprises a main air chamber, an elastic membrane, an inner compression ring and an outer compression ring, the outer end of the annular elastic membrane is tightly pressed and fixed on the main air chamber by the outer compression ring, and the top ends of the inner compression rings support vibration isolation loads; the air spring vibration isolator further comprises an additional air chamber, the additional air chamber is fixedly installed right below the main air chamber, an air inlet is formed in the side wall of the additional air chamber, 2-10 throttling holes are uniformly formed between the main air chamber and the additional air chamber, the main air chamber is made of aluminum alloy, titanium alloy or austenitic stainless steel which are not or weakly magnetic, and an annular rubber pad is arranged at the bottom of the main air chamber; the negative stiffness magnetic spring comprises a moving magnetic ring mounting piece, a moving magnetic ring and a fixed magnetic ring which are coaxially nested outwards along a radius from an axis, wherein the moving magnetic ring mounting piece is made of non-magnetic or weakly magnetic aluminum alloy, titanium alloy or austenitic stainless steel, the moving magnetic ring comprises an upper moving magnetic ring and a lower moving magnetic ring, the upper moving magnetic ring and the lower moving magnetic ring are arranged in a central symmetry mode relative to the axial height of the fixed magnetic ring, the upper moving magnetic ring and the lower moving magnetic ring are magnetized in opposite directions along the axial direction and fixedly connected to the outer wall of the moving magnetic ring mounting piece, an inner compression ring compresses the inner end of an annular elastic film and fixes the inner end of the moving magnetic ring mounting piece at the top end, a gap is formed between the moving magnetic ring and the fixed magnetic ring along the radial direction, the fixed magnetic ring is magnetized along the radial direction and fixedly installed on the inner wall of the main air chamber, a repulsion effect is formed between the fixed magnetic ring and the upper moving magnetic ring, and the fixed magnetic ring are in a repulsion effect.
Preferably, the fixed magnetic ring is magnetized along the radius to the axis, and the upper moving magnetic ring is magnetized along the axial direction downwards, or the fixed magnetic ring is magnetized along the radius from the axis outwards, and the upper moving magnetic ring is magnetized along the axial direction upwards.
Preferably, the fixed magnetic ring, the upper moving magnetic ring and the lower moving magnetic ring are permanent magnets or electromagnets.
Preferably, the orifice is circular, elliptical, or polygonal in shape.
Preferably, the diameter of the circumcircle of the throttle hole is 1 mm-10 mm.
Preferably, the volume of the additional air chamber is no more than 3 times the volume of the main air chamber.
Preferably, the elastic membrane is formed by vulcanizing a rubber material and a nylon cord or a polyester cord.
Preferably, the rubber pad is formed by vulcanizing a rubber material and a nylon cord or a polyester cord.
The technical innovation and the good effect of the invention are as follows:
(1) the technical scheme can realize the large bearing and near-zero frequency vibration isolation effects of the air spring vibration isolator. According to the invention, on one hand, the rigidity value and the inherent frequency of the air spring vibration isolator are reduced by serially connecting the additional air chambers, on the other hand, the near-zero frequency vibration isolation effect under the condition of large bearing is realized by connecting the negative rigidity magnetic springs in parallel, and the full-frequency-band micro-vibration interference in the environment where the ultra-precise instrument and equipment is located is effectively isolated. This is one of the innovative points of the present invention from the prior art.
(2) The throttling hole damping and the eddy current damping generated by the invention can effectively accelerate the vibration energy attenuation and shorten the system stabilization time. Orifices with different shapes, sizes and numbers are arranged between the main air chamber and the additional air chamber so as to introduce orifice damping and increase system damping; in addition, under disturbance excitation, eddy current damping generated in the main air chamber and the fixed magnetic ring fixing frame can effectively restrain the motion of the brake magnetic ring relative to the fixed magnetic ring, quickly attenuate vibration energy and shorten the system stabilization time. This is the second innovation point of the present invention from the prior art.
(3) According to the technical scheme, the floating height of the air spring vibration isolator is prevented from influencing the negative stiffness value by adopting a mode of nesting the coaxial magnetic ring negative stiffness magnetic springs, and meanwhile, the high integration characteristic is realized. The negative stiffness magnetic spring is formed by coaxially nesting a radially magnetized fixed magnetic ring and an axially magnetized movable magnetic ring, and the gap of the magnetic rings is vertical to the rising and falling movement direction of the air spring vibration isolator, so that the influence of the floating height of the air spring vibration isolator on the stiffness value of the negative stiffness magnetic spring is eliminated; the negative stiffness magnetic spring is nested and arranged in the main air chamber of the air spring vibration isolator, so that the integration level of the system is improved. This is the third innovation point of the present invention from the prior art.
(4) The invention can effectively avoid rigid collision under the excitation of impact disturbance. According to the invention, the rubber pad is arranged at the bottom of the main air chamber of the air spring vibration isolator as a protection measure of the negative stiffness magnetic spring, so that the phenomenon that the moving magnetic ring is rigidly collided with the bottom of the main air chamber under the excitation of impact disturbance to cause damage to the magnetic ring can be effectively avoided.
Drawings
FIG. 1 is a schematic three-dimensional cross-sectional view of a large load-bearing ultralow frequency air spring vibration isolator based on negative stiffness magnetic springs;
FIG. 2 is a schematic cross-sectional front view of a large load-bearing ultra-low frequency air spring vibration isolator based on negative stiffness magnetic springs;
FIG. 3 is a schematic view of the magnetization direction of the magnetic ring in the negative stiffness magnetic spring;
FIG. 4 is a force analysis diagram at the equilibrium position of a negative rate magnetic spring;
FIG. 5 is a force analysis graph of a negative rate magnetic spring moving upward away from equilibrium;
FIG. 6 is a force analysis graph of a negative rate magnetic spring moving downward away from equilibrium.
Description of part numbers in the figures: the device comprises an air inlet 1, a rubber pad 2, a main air chamber 3, an additional air chamber 4, an elastic membrane 5, an internal compression ring 6, an external compression ring 7, a fixed magnetic ring 8, a throttling hole 9, a movable magnetic ring 10, an upper movable magnetic ring 10a, a lower movable magnetic ring 10b and a movable magnetic ring 11.
Detailed Description
The following detailed description of embodiments of the invention refers to the accompanying drawings.
A large-bearing ultralow-frequency air spring vibration isolator based on negative stiffness magnetic springs comprises an air spring vibration isolator and negative stiffness magnetic springs, wherein the negative stiffness magnetic springs are coaxially nested in the air spring vibration isolator, the overall structure is in axial symmetry, the air spring vibration isolator comprises a main air chamber 3, an elastic membrane 5, an inner compression ring 6 and an outer compression ring 7, the outer compression ring 7 compresses and fixes the outer end of the annular elastic membrane 5 on the main air chamber 3, and the top end of the inner compression ring 6 supports a vibration isolation load; the air spring vibration isolator further comprises an additional air chamber 4, the additional air chamber 4 is fixedly installed right below the main air chamber 3, an air inlet 1 is formed in the side wall of the additional air chamber 4, 2-10 throttling holes 9 are uniformly formed between the main air chamber 3 and the additional air chamber 4, the main air chamber 3 is made of aluminum alloy, titanium alloy or austenitic stainless steel which is not magnetic conductive or weak magnetic conductive, and an annular rubber pad 2 is arranged at the bottom of the main air chamber 3; the negative stiffness magnetic spring comprises a movable magnetic ring mounting piece 11, a movable magnetic ring 10 and a fixed magnetic ring 8 which are coaxially nested outwards along the radius from the axis, the movable magnetic ring mounting piece 11 is made of non-magnetic conductive or weak-magnetic conductive aluminum alloy, the titanium alloy or austenitic stainless steel moving magnetic ring 10 comprises 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 about the axial height center of a fixed magnetic ring 8, the upper moving magnetic ring 10a and the lower moving magnetic ring 10b are magnetized in opposite directions along the axial direction and are fixedly connected to the outer wall of a moving magnetic ring mounting piece 11, an inner pressing ring 6 tightly presses and fixes the inner end of an annular elastic membrane 5 at the top end of the moving magnetic ring mounting piece 11, a gap is arranged between the moving magnetic ring 10 and a fixed magnetic ring 8 along the radial direction, the fixed magnetic ring 8 is magnetized along the radial direction and is coaxially and fixedly mounted on the inner wall of a main air chamber 3, the fixed magnetic ring 8 and the upper moving magnetic ring 10a have a repulsive force effect, and the fixed magnetic ring 8 and the lower moving magnetic ring 10b have a repulsive force effect.
In a specific embodiment, the fixed magnetic ring 8 is magnetized radially toward the axis, the upper moving magnetic ring 10a is magnetized axially downward, or the fixed magnetic ring 8 is magnetized radially outward from the axis, and the upper moving magnetic ring 10a is magnetized axially upward.
As a specific implementation manner, the fixed magnetic ring 8, the upper moving magnetic ring 10a and the lower moving magnetic ring 10b are permanent magnets or electromagnets.
In a specific embodiment, the orifice 9 has a circular, elliptical or polygonal shape.
In a specific embodiment, the diameter of the circumcircle of the orifice 9 is 1mm to 10 mm.
In a particular embodiment, the volume of the additional air chamber 4 is not greater than 3 times the volume of the main air chamber 3.
In a specific embodiment, the elastic membrane 5 is formed by vulcanizing a rubber material and a nylon cord or a polyester cord.
In a specific embodiment, the rubber pad 2 is formed by vulcanizing a rubber material and a nylon cord or a polyester cord.
An embodiment of the present invention is given below with reference to fig. 1 to 3.
Fig. 1 and fig. 2 are a schematic three-dimensional cross-sectional view and a schematic positive cross-sectional view of the positive and negative stiffness parallel vibration isolator provided by the invention, respectively, and fig. 3 is a schematic magnetization direction of a magnetic ring in a negative stiffness magnetic spring. As shown in fig. 1 and 2, the large-load ultra-low frequency air spring vibration isolator based on the negative stiffness magnetic spring provided by the invention comprises an air spring vibration isolator and the negative stiffness magnetic spring, wherein the air spring vibration isolator and the negative stiffness magnetic spring are coaxially installed and are arranged in parallel, and the whole body is in axial symmetry. The air spring vibration isolator comprises a main air chamber 3, an additional air chamber 4, an elastic membrane 5, an internal compression ring 6 and an external compression ring 7, wherein the main air chamber 3 and the additional air chamber 4 are made of 304 stainless steel materials, the volume of the additional air chamber 4 is 3 times of that of the main air chamber 3, the positive stiffness generated by the air spring vibration isolator is reduced by 75%, the inherent frequency is reduced by 50%, and the bearing capacity of the air spring vibration isolator is not changed. Elastic membrane 5 is the loop configuration with outer clamping ring 7, and interior clamping ring 6 is cylindrical structure, and elastic membrane 5 is vulcanized by rubber and nylon cord and forms, and the material of interior clamping ring 6 and outer clamping ring 7 is light aluminum alloy. The top end of the inner compression ring 6 supports vibration isolation load, the bottom of the inner compression ring 6 compresses and fixes the inner end of the elastic membrane 5 to the top end of the movable magnetic ring mounting part 11, and the outer compression ring 7 compresses and fixes the outer end of the elastic membrane 5 to the side wall of the main air chamber 3. The rubber pad 2 which is 2mm thick and is formed by vulcanizing rubber and nylon cords is arranged at the bottom of the main air chamber 3 and is used for preventing the movable 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 end of the chamber of the additional air chamber 4 are uniformly provided with 6 round holes with the diameter of phi 5mm along the circumference with the diameter of 40mm, the top end of the additional air chamber 4 is provided with a round hole with the diameter equal to the outer diameter of the chamber of the main air chamber 3, the depth is a round groove with the diameter of 1mm, the main air chamber 3 is coaxially and fixedly installed in the round groove at the top end of the additional air chamber 4, the bottom of the main air chamber 3 is opposite to the round hole at the top end of the chamber of the additional air chamber 4, and the main air chamber is used as a throttling hole 9 of the double-chamber air spring vibration isolator, so that the damping of the system is increased, the resonance peak value is reduced, and the stability time is shortened. The side wall of the additional air chamber 4 is provided with a circular air inlet 1, clean compressed air is introduced into the air inlet 1 through an air supply system to support vibration isolation load, the working air pressure of the air spring vibration isolator is 0.3MPa, and the floating height is 10 mm.
The negative stiffness magnetic spring comprises a fixed magnetic ring 8, a movable magnetic ring mounting piece 11 and a movable magnetic ring 10, wherein the movable magnetic ring mounting piece 11 is made of 304 stainless steel, the movable magnetic ring 10 comprises an upper movable magnetic ring 10a and a lower movable magnetic ring 10b, the fixed magnetic ring 8 is magnetized along a radius direction axis, the upper movable magnetic ring 10a is magnetized downwards along the axial direction, the lower movable magnetic ring 10b is magnetized upwards along the axial direction, and the magnetization direction of the magnetic rings is shown as an arrow in figure 3; the outer diameter of a fixed magnetic ring 8 is equal to the inner diameter of a main air chamber 3, the inner diameter of the fixed magnetic ring is larger than the outer diameter of an upper movable magnetic ring 10a and a lower movable magnetic ring 10b, the inner diameter of the upper movable magnetic ring 10a and the inner diameter of the lower movable magnetic ring 10b are equal to the outer diameter of a movable magnetic ring mounting piece 11, the fixed magnetic ring 8 is coaxially fixed on the inner wall of the main air chamber 3, the upper movable magnetic ring 10a and the lower movable magnetic ring 10b are coaxially nested and fixedly mounted on the outer wall of the movable magnetic ring mounting piece 11, the bottom of the upper movable magnetic ring 10a is connected with the top end of the lower movable magnetic ring 10b, the axial height center of the upper movable magnetic ring 10a is 10mm lower than that of the fixed magnetic ring 8, the magnetic rings are made of N50 brand neodymium iron boron, the residual magnetic induction intensity is 1.43T, and the relative magnetic conductivity 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, the internal compression ring 6 drives the movable magnetic ring 10 to move upwards for 10mm along the axial direction through the movable magnetic ring mounting part 11, and the axial height center of the fixed magnetic ring 8 is equal to the height of the bottom of the upper movable magnetic ring 10a and the height of the top of the lower movable magnetic ring 10 b. Under the interference of external vibration, the upper movable magnetic ring 10a and the lower movable magnetic ring 10b move relative to the fixed magnetic ring 8, magnetic induction lines generated by the movable magnetic ring 10 cut the main air chamber 3, so that eddy current is generated in the main air chamber 3, eddy current damping hinders the movable magnetic ring 10 from moving relative to the fixed magnetic ring 8, vibration attenuation is accelerated, and the stable adjustment time of the vibration isolation system is shortened.
FIG. 4 is a force analysis diagram of the balanced position of the negative stiffness magnetic spring, in which 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 applied to the negative stiffness magnetic spring is the repulsive force f of the upper moving magnetic ring 10a and the lower moving magnetic ring 10b from the fixed magnetic ring 81And f2And (4) summing. At the balance position, the top end 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 force f1And f2The fixed magnetic ring 8 points to the moving magnetic ring along the horizontal direction, and the magnetic force borne by the negative stiffness magnetic spring at the balance position is 0 due to the symmetry of the negative stiffness magnetic spring structure.
FIG. 5 is a force analysis diagram of the negative-stiffness magnetic spring moving upward from the equilibrium position, where the top end 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 f1Pointing to the axis along the central connecting line of the fixed magnetic ring 8 and the upper movable magnetic ring 10a, f2Pointing to the axis along the central connecting line of the fixed magnetic ring 8 and the lower moving magnetic ring 10b, f due to the symmetry of the negative stiffness magnetic spring structure1And f2The components in the radial direction are mutually offset, and the axial components which are mutually superposed force the negative stiffness magnetic spring to deviate from the balance position and move upwards in the axial direction.
FIG. 6 is a force analysis diagram of the negative-stiffness magnetic spring moving downward from the equilibrium position, where the top end 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 stationary magnetic ring 8, and f1Away from the axis along the central connecting line of the fixed magnetic ring 8 and the upper movable magnetic ring 10a, f2The central connecting line of the fixed magnetic ring 8 and the lower moving magnetic ring 10b is far away from the axis, f is the symmetry of the negative stiffness magnetic spring structure1And f2The components in the radial direction are mutually offset, and the axial components which are mutually superposed force the negative stiffness magnetic spring to deviate from the balance position and move downwards along the axial direction.
Claims (8)
1. A large-bearing ultralow-frequency air spring vibration isolator based on negative stiffness magnetic springs comprises an air spring vibration isolator and negative stiffness magnetic springs, wherein the negative stiffness magnetic springs are coaxially nested in the air spring vibration isolator, the overall structure is in axial symmetry, the air spring vibration isolator comprises a main air chamber (3), an elastic membrane (5), an inner compression ring (6) and an outer compression ring (7), the outer end of the annular elastic membrane (5) is pressed and fixed on the main air chamber (3) by the outer compression ring (7), and the top end of the inner compression ring (6) supports vibration isolation load; the method is characterized in that: the air spring vibration isolator further comprises an additional air chamber (4), the additional air chamber (4) is fixedly installed right below the main air chamber (3), an air inlet hole (1) is formed in the side wall of the additional air chamber (4), 2-10 throttling holes (9) are uniformly formed between the main air chamber (3) and the additional air chamber (4), the main air chamber (3) is made of non-magnetic or weak-magnetic aluminum alloy, titanium alloy or austenitic stainless steel, and an annular rubber pad (2) is arranged at the bottom of the main air chamber (3); the negative stiffness magnetic spring comprises a moving magnetic ring mounting piece (11), a moving magnetic ring (10) and a fixed magnetic ring (8) which are coaxially nested outwards along the radius from the axis, the moving magnetic ring mounting piece (11) is made of non-magnetic or weakly magnetic aluminum alloy, titanium alloy or austenitic stainless steel, the moving magnetic ring (10) comprises 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 arranged in a central symmetry way around the axial height of the fixed magnetic ring (8), the upper moving magnetic ring (10a) and the lower moving magnetic ring (10b) are magnetized reversely along the axial direction and are fixedly connected to the outer wall of the moving magnetic ring mounting piece (11), an inner pressure ring (6) presses and fixes the inner end of an annular elastic membrane (5) at the top end of the moving magnetic ring mounting piece (11), a gap is arranged between the moving magnetic ring (10) and the fixed magnetic ring (8) along the radial direction, and the fixed magnetic ring (8) is magnetized along the radial direction and is coaxially and fixedly installed on the inner wall of a main air chamber (3), the fixed magnetic ring (8) and the upper movable magnetic ring (10a) have a repulsive force effect, and the fixed magnetic ring (8) and the lower movable magnetic ring (10b) have a repulsive force effect.
2. The negative-stiffness magnetic spring-based large-load ultralow-frequency air spring vibration isolator is characterized in that: the fixed magnetic ring (8) is magnetized along the radius to the axis, the upper movable magnetic ring (10a) is magnetized along the axial direction, or the fixed magnetic ring (8) is magnetized along the radius from the axis to the outside, and the upper movable magnetic ring (10a) is magnetized along the axial direction to the top.
3. The negative-stiffness magnetic spring-based large-load ultralow-frequency air spring vibration isolator is characterized in that: the fixed magnetic ring (8), the upper movable magnetic ring (10a) and the lower movable magnetic ring (10b) are permanent magnets or electromagnets.
4. The negative-stiffness magnetic spring-based large-load ultralow-frequency air spring vibration isolator is characterized in that: the shape of the throttle hole (9) is circular, oval or polygonal.
5. The large-load-bearing ultralow-frequency air spring vibration isolator based on the negative-stiffness magnetic spring as claimed in claim 1 or 4, is characterized in that: the diameter of the circumcircle of the throttle hole (9) is 1 mm-10 mm.
6. The negative-stiffness magnetic spring-based large-load ultralow-frequency air spring vibration isolator is characterized in that: the volume of the additional air chamber (4) is not more than 3 times of the volume of the main air chamber (3).
7. The negative-stiffness magnetic spring-based large-load ultralow-frequency air spring vibration isolator is characterized in that: the elastic membrane (5) is formed by vulcanizing a rubber material and a nylon cord or a polyester cord.
8. The negative-stiffness magnetic spring-based large-load ultralow-frequency air spring vibration isolator is characterized in that: the rubber pad (2) is formed by vulcanizing a rubber material and a nylon cord or a polyester cord.
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| CN112343393B (en) * | 2020-10-21 | 2021-10-26 | 北京工业大学 | Amplification type negative stiffness friction damping wall |
| CN112411782B (en) * | 2020-10-21 | 2021-10-26 | 北京工业大学 | Balance weight lever type negative stiffness friction damper |
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