Magnetic hybrid quasi-zero stiffness vibration isolator, load adaptive control system and method

Abstract

The present invention discloses a magnetic hybrid quasi-zero stiffness vibration isolator, which includes an airbag positive stiffness mechanism and a magnet negative stiffness mechanism; the airbag positive stiffness mechanism is a single-curved airbag air spring, which includes an upper cover plate, a lower cover plate and an elastic airbag body, and the upper and lower cover plates are arranged horizontally and facing each other; the upper and lower ends of the elastic airbag body are respectively connected to the upper and lower cover plates; the magnet negative stiffness mechanism is installed in the air spring body, the upper end of the magnet negative stiffness mechanism is connected to the upper cover plate, and the lower end of the magnet negative stiffness mechanism is connected to the lower cover plate. The present invention also discloses a load adaptive control system and method based on the vibration isolator as described above. The beneficial effects of the present invention are as follows: introducing a negative stiffness mechanism to offset the positive stiffness of the elastic element can effectively solve the contradiction between low natural frequency and small static deformation; a load adaptive control system and method are proposed, using the mechanism of optimal matching of positive and negative stiffness to further reduce the natural frequency of the airbag, and improving the load adaptive ability of the vibration isolator through a semi-active control mechanism.

Description

Technical Field

[0001] The present invention relates to the technical field of vibration and noise control, and particularly relates to a magnetic hybrid quasi-zero stiffness isolator and a load adaptive control method. Background Art

[0002] Vibration affects people's real life in various forms all the time. It brings both life conveniences such as wonderful music, radio communication, screening and polishing, and endless hazards such as bridge collapse, noise pollution, deformation and damage. A passive isolator is a load-bearing energy-consuming component, which has the advantages of simple structure, low energy consumption and good economy, and is the main component for isolating the transmission of mechanical vibration to the equipment body. With the development of ultra-precision manufacturing and measurement, space exploration, transportation and weapons, etc. towards extreme working conditions or ultimate performance, the environmental vibration is complex and the low frequency is prominent. Ultra-low frequency vibration isolation must be carried out, which requires the isolation natural frequency to be nearly zero, that is, the stiffness to be nearly zero, which cannot be achieved by traditional vibration isolation methods.

[0003] A quasi-zero stiffness isolator is a passive non-linear vibration isolation device that combines positive and negative stiffness elastic elements in parallel near the static equilibrium position to obtain the characteristics of high static and low dynamic stiffness. The high static stiffness can maintain the load-bearing capacity of the system and increase the stability of the system; while the low dynamic stiffness can reduce the natural frequency of the system and broaden the vibration isolation frequency band of the system. The quasi-zero stiffness isolator can obtain the characteristics of high static stiffness for supporting the isolated equipment and low dynamic stiffness for reducing the vibration transmission rate, solve the contradiction that it is difficult to have both a low natural frequency and a small static deformation, and enable the isolator to have both a large load-bearing capacity and a nearly zero stiffness to achieve nearly zero vibration transmission.

[0004] The matching design of positive and negative stiffness is the key for the quasi-zero stiffness vibration isolation system to always have nearly zero stiffness at the ideal static equilibrium position, but it is very difficult to achieve in engineering practice. Due to the machining accuracy and the matching problem of the load mass during installation, there will inevitably be a situation where the load is not perfect in engineering: the load does not match the design value, resulting in the static equilibrium point not being the lowest stiffness, and at this time the system does not work at the ideal static equilibrium position. Under imperfect load, the dynamic response of the system undergoes rigid drift, and the vibration isolation effect is reduced or even deteriorated. In response to this problem, relevant researches such as invention patents CN 106402262 B, CN 104455181 A, CN203641365U, CN202132428U and CN102678804 A etc. mostly only adjust the positive stiffness, or manually adjust the positive and negative stiffness, and none of them can achieve online adaptive adjustment. Summary of the Invention

[0005] The purpose of the present invention is to provide a magnetic hybrid quasi-zero stiffness isolator, a load adaptive control system and a method in view of the deficiencies of the prior art.

[0006] The technical solution adopted by the present invention is as follows: a magnetic hybrid quasi-zero stiffness vibration isolator, which includes an airbag positive stiffness mechanism and a magnet negative stiffness mechanism; the airbag positive stiffness mechanism is a single-curved airbag air spring, which includes an upper cover plate, a lower cover plate and an elastic airbag body, and the upper and lower cover plates are horizontally and oppositely arranged; the upper and lower ends of the elastic airbag body are respectively connected to the upper and lower cover plates, and the three enclose to form a closed air spring body; the air spring body is provided with an air inlet and an air outlet, and the air inlet is connected to an externally provided air path holding device; the magnet negative stiffness mechanism is installed inside the air spring body, the upper end of the magnet negative stiffness mechanism is connected to the upper cover plate, and the lower end of the magnet negative stiffness mechanism is connected to the lower cover plate.

[0007] According to the above solution, the magnet negative stiffness mechanism includes a middle permanent magnet, two external permanent magnets and two groups of electromagnets; the middle permanent magnet is vertically arranged, and its upper end is connected to the lower part of the upper cover plate through a fixing frame; the two external permanent magnets are symmetrically arranged on both sides of the middle permanent magnet, and the same poles of adjacent permanent magnets are arranged opposite to each other; one end of the external permanent magnet is connected to the electromagnet, and the other end of the electromagnet is fixed on the column, and the lower end of the column is connected to the lower cover plate; the electromagnet coil is connected to a DC regulated power supply to form a circuit.

[0008] According to the above solution, the permanent magnet is made of neodymium iron boron material; a channel is opened in the lower cover plate or the upper cover plate, one end of the channel is connected to the air inlet of the air spring body, and the other end of the channel can be connected to an externally provided air path holding device.

[0009] The present invention also provides a load adaptive control system based on the above-mentioned magnetic hybrid quasi-zero stiffness vibration isolator, which includes a signal acquisition module, a control module and an execution module; the magnetic hybrid quasi-zero stiffness vibration isolator is respectively connected to the signal acquisition module and the execution module; the signal acquisition module and the execution module are respectively connected to the control module;

[0010] The signal acquisition module is used to detect and obtain three different types of signals of displacement, current and pressure of the magnetic hybrid quasi-zero stiffness vibration isolator as the input of the control module;

[0011] The control module is used to receive the signals input by the signal acquisition module and judge whether to output control signals to the execution module;

[0012] The execution module is used to receive the control signals output by the control module and output control current and charge / discharge gas to the magnetic hybrid quasi-zero stiffness vibration isolator.

[0013] According to the above solution, the execution module includes a DC regulated power supply and an air path holding device, and the DC regulated power supply is connected to the coil of the electromagnet to form a circuit loop; the air path holding device is internally communicated with the air spring body, and an inflation solenoid valve is configured on this pipeline; the execution module also includes a deflation solenoid valve arranged at the air outlet of the air spring body.

[0014] According to the above solution, the signal acquisition module includes a displacement sensor, a digital display ammeter, a pressure sensor, a power amplifier, and an LMS multi-functional data acquisition system. The displacement sensor is arranged on the upper surface of the upper cover plate; the digital display ammeter is installed on the loop where the electromagnet coil is connected to the DC regulated power supply; the pressure sensor is fixed on the lower cover plate and is located inside the airbag positive stiffness mechanism; the displacement sensor, the digital display ammeter, and the pressure sensor are respectively connected to the input end of the power amplifier, and respectively input the measured displacement signal, current signal, and pressure signal into the power amplifier for amplification; the output end of the power amplifier is connected to the LMS multi-functional data acquisition system, and the LMS multi-functional data acquisition system is connected to the control module; the LMS multi-functional data acquisition system is used to collect the amplified signal and send the signal to the control module.

[0015] According to the above solution, the control module includes a DSP controller. The DSP controller is respectively connected to the LMS multi-functional data acquisition system of the signal acquisition module, the DC regulated power supply, the inflation solenoid valve and the deflation solenoid valve of the air circuit holding device; the execution module starts the DC regulated power supply to output a control current according to the control signal output by the control module, controls the solenoid valve, and inflates and deflates the air spring body.

[0016] The present invention also provides a load adaptive control method for a magnetic-gas hybrid quasi-zero stiffness vibration isolator, and the method includes the following steps:

[0017] Step 1: Provide the magnetic-gas hybrid quasi-zero stiffness vibration isolator as described above, and the load adaptive control system as described above, and install them; take the height of the upper cover plate when the center line of the middle permanent magnet is horizontally collinear with the center lines of the two outer permanent magnets as the ideal equilibrium position H of the magnetic-gas hybrid quasi-zero stiffness vibration isolator, and input it into the control module of the load adaptive control system;

[0018] Step 2: The displacement sensor detects the working height Y of the airbag positive stiffness mechanism, and the control module of the load adaptive control system determines whether it is consistent with the ideal equilibrium position H of the magnetic-gas hybrid quasi-zero stiffness vibration isolator; if not, the control module makes the air spring body inflate and deflate through the execution module, adjusts the air pressure of the air spring body until the working height Y of the airbag positive stiffness mechanism is consistent with the ideal equilibrium position H of the magnetic-gas hybrid quasi-zero stiffness vibration isolator;

[0019] Step 3: The digital display ammeter obtains the current in the circuit, and the pressure sensor detects the pressure change in the air spring body. The changed pressure value and the current value are collected by the LMS multi-functional data acquisition system and then input into the control module. According to the conditions that the air spring body pressure and the magnet current need to meet to achieve near-zero stiffness, it is judged whether the positive and negative stiffnesses match. If they do not match, the control module outputs a target current through the DC regulated power supply to make the regulated magnet negative stiffness mechanism adapt to the airbag positive stiffness mechanism of the current load.

[0020] According to the above scheme, the air spring body pressure and the magnet current to achieve near-zero stiffness should satisfy the following relationship:

[0021]

[0022]

[0023] In the above formula, where F is the current load, with the unit of N; P at is the atmospheric pressure, with the unit of Pa; P sur0 , P0, S ef0 and V0 are respectively the gauge pressure, absolute pressure, effective load-bearing area of the bladder wall, and volume of the air spring body when the air spring body is at the rated working height H. The units of these four parameters are Pa, Pa, m 2 , m 2 ; δ z is the vertical displacement value of the vibration isolator, with the unit of m; S ef is the effective load-bearing area of the vibration isolator, with the unit of m 2 ; n is the polytropic index, taking 1 for the isothermal process and 1.4 for the adiabatic process; S is the cross-sectional area of the magnetic circuit, with the unit of m 2 ; δ is the air gap length, with the unit of m; N is the number of turns of the coil, with the unit of turns; I is the current intensity flowing through the coil, with the unit of A; μ0 is the vacuum permeability, with the unit of H / m.

[0024] According to the above scheme, in Step 2, when the control module detects that Y > H, the control module activates the air release solenoid valve to discharge the gas in the air spring body; when Y < H, the control module activates the air filling solenoid valve to fill the air spring body with gas.

[0025] The beneficial effects of the present invention are:

[0026] 1. The present invention introduces a negative stiffness mechanism to offset the positive stiffness of the elastic element, which can effectively solve the contradiction between low natural frequency and small static deformation, and achieve low-frequency or even ultra-low-frequency vibration isolation. The positive stiffness of the airbag has the advantages of excellent load-bearing capacity, low natural frequency, large dynamic displacement, good reset characteristics, no standing wave effect, adjustable stiffness and damping, etc.; the negative stiffness of the magnet has the advantages of no mechanical wear, compact structure, adjustable stiffness, convenient installation and high magnetic energy utilization rate. The parallel connection of the two makes the magnetic air hybrid quasi-zero stiffness vibration isolator not only have high static and low dynamic stiffness, but also can follow the change of the load, automatically adjust the positive and negative stiffness to adapt to the current load, and keep the system always working at the ideal equilibrium position and near-zero stiffness state, thus improving the adaptability and vibration isolation performance of this type of vibration isolator.

[0027] 2. Since the near-zero stiffness interval of the quasi-zero stiffness vibration isolator is sensitive to the load mass, affected by processing accuracy, installation error or working condition changes, the combined stiffness of the quasi-zero stiffness vibration isolator system at the working point will deviate from the designed matching state, which may lead to vibration amplification of the system or even instability and damage of the elastic element. The present invention combines the quasi-zero stiffness vibration isolation technology with the semi-active control technology, aiming at the deficiency of the existing quasi-zero stiffness vibration isolator with a single fixed load, and proposes a load adaptive control system and method. By using the mechanism of optimal matching of positive and negative stiffness to further reduce the natural frequency of the airbag, and through the semi-active control mechanism to improve the load adaptive ability of the vibration isolator. When the load mass of the equipment to be vibration isolated changes, such as replacing the equipment or adding other accessories to the equipment, the working height of the airbag can be maintained unchanged. After the positive stiffness of the airbag changes due to the change of the internal pressure, the negative stiffness of the magnet can be matched with the positive stiffness of the airbag by automatically adjusting the control current, and the combined action of the airbag pressure and the electromagnetic current is used to adapt to the load requirements of different masses, and near-zero stiffness and low-frequency vibration isolation can be always achieved within a certain load range.

[0028] 3. The present invention adopts a new configuration in which the negative stiffness of the magnet is integrated in parallel into the intelligent airbag positive stiffness, meeting the multi-functional integration requirements of shipboard electromechanical equipment for vibration reduction, pressure bearing and weight reduction; the load adaptive control method is a stiffness semi-active control strategy that adjusts the internal pressure of the airbag and the electromagnetic current online according to the load mass, meeting the requirements of always maintaining near-zero stiffness and low-frequency vibration isolation under variable load conditions; the device and method can meet the high-performance vibration reduction requirements of shipboard electromechanical equipment and the engineering application needs of low-frequency line spectrum chaos, providing an efficient and reliable way for building quiet ships, comfortable ships and ultra-micro amplitude vibration reduction of precision instruments.

[0029] 4. The present invention has the advantages of compact structure, convenient maintenance, light weight, high reliability, large load-bearing capacity, good environmental adaptability, etc., and is also suitable for full-frequency band and ultra-low-frequency vibration isolation of time-varying systems in narrow spaces and complex environments such as weapon equipment, precision instruments, and aerospace. Description of the Drawings

[0030] Figure 1 This is a structural schematic diagram of the magnetic hybrid quasi-zero stiffness vibration isolator in the present invention.

[0031] Figure 2 This is a schematic diagram of the airbag positive stiffness mechanism in the present invention.

[0032] Figure 3 This is a schematic diagram of the magnet negative stiffness mechanism in the present invention.

[0033] Figure 4 This is a connection schematic diagram of the magnetic hybrid quasi-zero stiffness vibration isolator and the load adaptive control system in the present invention.

[0034] Figure 5 This is a structural schematic diagram of the airbag positive stiffness mechanism and the air circuit holding device.

[0035] Figure 6 This is a flowchart of the control program for the ideal equilibrium position of the airbag when the load is imperfect.

[0036] Among them: 1. Airbag positive stiffness mechanism; 1.1. Upper cover plate; 1.2. Lower cover plate; 1.3. Elastic bladder; 1.4. Wire hole; 1.5. Channel; 2. Magnet negative stiffness mechanism; 2.1. Middle permanent magnet; 2.2. Outer permanent magnet; 2.3. Electromagnet; 2.4. Column; 2.5. Fixed frame; 3. Displacement sensor; 4. Digital display ammeter; 5. Pressure sensor; 6. DC regulated power supply. Specific implementation mode

[0037] To better understand the present invention, the present invention will be further described below in conjunction with the accompanying drawings and specific embodiments.

[0038] As Figure 1 and Figure 2 shown, a magnetic hybrid quasi-zero stiffness vibration isolator includes an airbag positive stiffness mechanism 1 and a magnet negative stiffness mechanism 2; the airbag positive stiffness mechanism 1 is a single-curved bladder air spring, which includes an upper cover plate 1.1, a lower cover plate 1.2 and an elastic bladder 1.3, and the upper and lower cover plates 1.2 are arranged horizontally and facing each other; the upper end and the lower end of the elastic bladder 1.3 are respectively connected to the upper and lower cover plates 1.2, and the three enclose to form a closed air spring body; the air spring body is provided with an air inlet and an air outlet, and the air inlet is connected to an externally provided air circuit holding device; the magnet negative stiffness mechanism 2 is installed in the air spring body, the upper end of the magnet negative stiffness mechanism 2 is connected to the upper cover plate 1.1, and the lower end of the magnet negative stiffness mechanism 2 is connected to the lower cover plate 1.2.

[0039] Preferably, as Figure 3As shown, the magnet negative stiffness mechanism 2 includes a middle permanent magnet 2.1, two outer permanent magnets 2.2 and two sets of electromagnets 2.3; the middle permanent magnet 2.1 is vertically arranged, and its upper end is connected to the lower part of the upper cover plate 1.1 through a fixing bracket 2.5; the two outer permanent magnets 2.2 are symmetrically arranged on both sides of the middle permanent magnet 2.1, and the like poles of adjacent permanent magnets are arranged opposite to each other; one end of the outer permanent magnet 2.2 is connected to the electromagnet 2.3, the other end of the electromagnet 2.3 is fixed on the column 2.4, and the lower end of the column 2.4 is connected to the lower cover plate 1.2; the coil of the electromagnet 2.3 is connected to the DC regulated power supply 6 to form a loop.

[0040] Preferably, each permanent magnet is made of neodymium iron boron material.

[0041] In the present invention, three permanent magnets and two sets of electromagnets 2.3 are combined and configured to form a magnetic negative stiffness spring. The electromagnet 2.3 is composed of an iron core wound with an enameled wire coil. One end of the electromagnet 2.3 is connected to the outer permanent magnet 2.2, and the other end is fixedly connected to the column 2.4; the coils of the two sets of electromagnets 2.3 can be connected to the DC regulated power supply 6. The upper end of the fixing bracket 2.5 is connected to the bottom of the upper cover plate 1.1, and the lower end of the fixing bracket 2.5 is a U-shaped opening structure, and the upper end of the middle permanent magnet is fixed in the U-shaped opening structure.

[0042] In the present invention, a channel 2.6 is provided in the lower cover plate 1.2 or the upper cover plate 1.1. One end of the channel 2.6 is connected to the air inlet of the air spring body, and the other end of the channel 2.6 can be connected to an external air path holding device. Specifically, in this embodiment, the channel 2.6 is provided in the lower cover plate 1.2; a wire hole 1.4 is also provided on the lower cover plate 1.2, and wires and the like involved later are led out from the wire hole 1.4.

[0043] As Figure 4 Shown is a load adaptive control system based on the above-mentioned magnetic gas hybrid quasi-zero stiffness vibration isolator, including a signal acquisition module, a control module and an execution module; the magnetic gas hybrid quasi-zero stiffness vibration isolator is respectively connected to the signal acquisition module and the execution module; the signal acquisition module and the execution module are respectively connected to the control module;

[0044] The signal acquisition module is used to detect and obtain three different types of signals of displacement, current and pressure of the magnetic gas hybrid quasi-zero stiffness vibration isolator as the input of the control module;

[0045] The control module is used to receive the signals input by the signal acquisition module and judge whether to output control signals to the execution module;

[0046] The execution module is used to receive the control signals output by the control module and output control current and charge / discharge gas to the magnetic gas hybrid quasi-zero stiffness vibration isolator.

[0047] In this embodiment, the magnetic hybrid quasi-zero stiffness vibration isolator is used to support ship's electromechanical equipment and implement low-frequency vibration isolation.

[0048] Preferably, the execution module includes a DC regulated power supply 6 and a gas path holding device. The DC regulated power supply 6 is connected to the coil of the electromagnet 2.3 to form a circuit loop. The gas path holding device is connected to the inside of the air spring body through a pipeline, and an inflation solenoid valve is arranged on this pipeline. The execution module further includes a deflation solenoid valve arranged at the air outlet of the air spring body.

[0049] Preferably, the signal acquisition module includes a displacement sensor 3, a digital display ammeter 4, a pressure sensor 5, a power amplifier, and an LMS multi-functional data acquisition system. The displacement sensor 3 is arranged on the upper surface of the upper cover plate 1.1. The digital display ammeter 4 is installed on the loop connecting the coil of the electromagnet 2.3 and the DC regulated power supply 6. The pressure sensor 5 is fixed on the lower cover plate 1.2 and is located inside the airbag positive stiffness mechanism 1. The displacement sensor 3, the digital display ammeter 4, and the pressure sensor 5 are respectively connected to the input end of the power amplifier, and the measured displacement signal, current signal, and pressure signal are respectively input to the power amplifier for amplification. The output end of the power amplifier is connected to the LMS multi-functional data acquisition system, and the LMS multi-functional data acquisition system is connected to the control module. The LMS multi-functional data acquisition system is used to collect the amplified signals and send the signals to the control module.

[0050] Preferably, the control module includes a DSP controller. The DSP controller is respectively connected to the LMS multi-functional data acquisition system of the signal acquisition module, the DC regulated power supply 6, and the inflation solenoid valve and deflation solenoid valve of the gas path holding device. The execution module starts the DC regulated power supply 6 to output a control current according to the control signal output by the control module, controls the solenoid valve, and inflates and deflates the air spring body.

[0051] In the present invention, the signal acquisition module and the magnetic hybrid quasi-zero stiffness vibration isolator are connected by an electrical connection cable. The electrical connection cable is integrated in a hub and is connected to the DSP controller through the hub.

[0052] The following further describes the control method of the present invention by using the magnetic hybrid quasi-zero stiffness vibration isolator for ship's electromechanical equipment.

[0053] As Figure 6 shown, a load adaptive control method for a magnetic hybrid quasi-zero stiffness vibration isolator, the method includes the following steps:

[0054] Step 1: Provide the magnetic hybrid quasi-zero stiffness isolator and the supporting load adaptive control system as described above, and install them; take the height of the upper cover plate 1.1 when the center line of the middle permanent magnet 2.1 is horizontally collinear with the center lines of the two outer permanent magnets 2.2 as the ideal equilibrium position H of the magnetic hybrid quasi-zero stiffness isolator, and input it into the control module of the load adaptive control system.

[0055] In this embodiment, the vibration isolation object is ship electromechanical equipment, and the magnetic hybrid quasi-zero stiffness isolator is installed at the bottom of the ship electromechanical equipment. The ship electromechanical equipment is isolated from low-frequency vibration by the magnetic hybrid quasi-zero stiffness isolator being in the ideal equilibrium position H.

[0056] Step 2: The displacement sensor 3 detects the working height Y of the airbag positive stiffness mechanism 1 (i.e., the real-time height of the upper cover plate 1.1), and the control module of the load adaptive control system determines whether it is consistent with the ideal equilibrium position H of the magnetic hybrid quasi-zero stiffness isolator; if not, the control module makes the air spring body inflate or deflate through the execution module, adjusts the air pressure of the air spring body until the working height Y of the airbag positive stiffness mechanism 1 is consistent with the ideal equilibrium position H of the magnetic hybrid quasi-zero stiffness isolator.

[0057] Specifically, when the control module detects that Y > H, the control module activates the exhaust solenoid valve to discharge the gas in the air spring body; when Y < H, the control module activates the inflation solenoid valve to inflate the air spring body.

[0058] Step 3: The digital display ammeter 4 obtains the current in the circuit, and the pressure sensor 5 detects the pressure change in the air spring body. The changed pressure value and the current value are collected by the LMS multi-functional data acquisition system and input into the control module. According to the conditions that the air spring body pressure and the magnet current required to achieve near-zero stiffness need to meet, it is judged whether the positive and negative stiffnesses match; if not, the control module inputs corresponding control signals to the DC regulated power supply 6, so as to output the target current required by the magnet negative stiffness mechanism 2, and make the regulated magnet negative stiffness mechanism 2 match the airbag positive stiffness mechanism 1 of the current load.

[0059] In the present invention, when the vibration isolation object is pressed onto the upper cover plate 1.1, the airbag positive stiffness mechanism 1 provides support, and the magnet negative stiffness mechanism 2 configured by combining three permanent magnets and two sets of electromagnets 2.3 always matches the positive stiffness of the current load. In order to maintain the balance position of the airbag positive stiffness mechanism 1 unchanged and the near-zero stiffness with positive and negative stiffness matching, the following conditions should be met, that is, the following relationships should be satisfied between the load mass and the airbag pressure, and between the air spring body pressure and the electromagnetic current respectively:

[0060]

[0061]

[0062] In the above formula, F is the current load (unit: N); P at is the atmospheric pressure (unit: Pa); P sur0 , P0, S ef0 and V0 are respectively the gauge pressure (unit: Pa), absolute pressure (unit: Pa), effective load-bearing area of the bladder wall (unit: m 2 ), and the volume of the air spring body (unit: m 2 ) of the gas in the air spring body when the air spring body is at the rated working height H; δ z is the vertical displacement value of the vibration isolator (unit: m), S ef is the effective load-bearing area of the vibration isolator (unit: m 2 ); n is the polytropic index, taking 1 for the isothermal process and 1.4 for the adiabatic process; S is the cross-sectional area of the magnetic circuit (unit: m 2 ), δ is the air gap length (unit: m), N is the number of turns of the coil (unit: turns), I is the current intensity flowing through the coil (unit: A), and μ0 is the magnetic permeability of vacuum (unit: H / m). As Figure 2 and Figure 5 shown, when the load mass changes, the equilibrium position of the positive stiffness mechanism 1 of the airbag will also change accordingly, and the effective area, the volume and pressure of the gas in the airbag will change correspondingly to reach a new equilibrium. In order to maintain the ideal equilibrium position of the positive stiffness mechanism 1 of the airbag of the magnetic-gas hybrid quasi-zero stiffness vibration isolator, a gas source holding device for maintaining the air circuit is designed, and a solenoid valve with adjustable opening is selected as the actuator, taking into account the functions of rapid adjustment and fine adjustment, and a zoning control method is implemented. The fast adjustment area can quickly bring the airbag to near the target pressure, while the fine adjustment area can accurately adjust the air spring body to the target pressure value.

[0063] As Figure 3 shown, the magnet negative stiffness mechanism 2 utilizes the principle of attraction between opposite magnetic poles to generate a negative stiffness effect. By changing the direction of the applied current, the original magnetic field can be enhanced or weakened; by changing the magnitude of the applied current, the electromagnetic negative stiffness can be continuously adjusted online.

[0064] The present invention adopts a feedback control mode, using the air pressure of the air spring body corresponding to the load mass as the feedback input signal, and the current signal after passing through the control system as the feedback output signal, jointly adjusting the airbag pressure and the electromagnetic current until the original equilibrium position is reached and then closing the adjustment system, forming a feedback control system with adjustable stiffness. The specific control process is as Figure 6 shown.

[0065] In the present invention, the air spring body pressure control design must pay attention to displacement monitoring and pressure regulation. The working height Y of the airbag positive stiffness mechanism 1 is detected by the displacement sensor 3, and it is judged by the control module whether it is equal to the ideal equilibrium position H of the magnetic hybrid quasi-zero stiffness vibration isolator. When Y > H, the gas in the air spring body is discharged. When Y < H, the air spring body is inflated through the gas path holding device until the working height of the airbag positive stiffness mechanism 1 is restored to the ideal equilibrium position H by adjusting the air pressure. The solenoid valve controls the on-off of the inflation gas path and the exhaust gas path, so that the working height of the air spring body is always accurately and quickly controlled at the ideal static equilibrium position satisfying near-zero stiffness.

[0066] In the present invention, the current control design of the magnet negative stiffness must pay attention to pressure monitoring and current regulation. Since the working height of the airbag remains unchanged due to the change of the load mass, the internal pressure of the air spring body has changed accordingly, and the positive and negative stiffnesses do not match. The change of the internal air pressure of the air spring body is detected by the pressure sensor 5, and the changed pressure value is input into the load adaptive control system. According to the conditions that the pressure and current for realizing near-zero stiffness need to meet, it is judged whether the positive and negative stiffnesses match. If they do not match, a corresponding control signal is input into the DC regulated power supply 6 through the DSP controller, so as to output the target current required by the magnet negative stiffness mechanism 2, making the regulated magnet negative stiffness mechanism 2 match the changed airbag positive stiffness mechanism 1, and obtaining the optimal matching value of the internal air pressure and the electromagnetic current in the airbag under the current load, so as to always maintain the low-frequency vibration isolation performance of the system under near-zero stiffness under variable load conditions.

[0067] In summary, the present invention combines the generation law of magnet negative stiffness and the matching criterion of positive and negative stiffnesses, and has a new configuration of quasi-zero stiffness vibration isolation with load adaptive ability and a new semi-active control method. This vibration isolator not only has high static and low dynamic stiffness, but also the working height of the air spring body can remain unchanged after the equipment on the vibration-isolated object is replaced, other accessories are added, or the operating state changes. And after the positive stiffness of the air spring body changes due to the change of the internal pressure, the air pressure of the air spring body and the electromagnetic current always act jointly to adapt to the load requirements of different masses, and the system always works at the ideal equilibrium position and near-zero stiffness state within a certain load range, so it has good low-frequency and ultra-low-frequency vibration isolation effects.

[0068] The content not described in detail in this specification belongs to the prior art well-known to those skilled in the art. The above is only a preferred embodiment of the present invention, and is not used to limit the protection scope of the present invention. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A load adaptive control method for a magnetic hybrid quasi-zero stiffness vibration isolator, characterized in that The method includes the following steps: Step 1: Provide a magnetic hybrid quasi-zero stiffness vibration isolator and a load adaptive control system, and install them; Take the height of the upper cover plate when the center line of the middle permanent magnet is horizontally collinear with the center lines of the two outer permanent magnets as the ideal equilibrium position H of the magnetic hybrid quasi-zero stiffness vibration isolator, and input it into the control module of the load adaptive control system; Step 2: The displacement sensor detects the working height Y of the airbag positive stiffness mechanism, and the control module of the load adaptive control system determines whether it is consistent with the ideal equilibrium position H of the magnetic hybrid quasi-zero stiffness vibration isolator; If not, the control module uses the execution module to inflate and deflate the air spring body, adjust the air pressure of the air spring body until the working height Y of the airbag positive stiffness mechanism is consistent with the ideal equilibrium position H of the magnetic hybrid quasi-zero stiffness vibration isolator; Step 3: The digital display ammeter obtains the current in the circuit, and the pressure sensor detects the pressure change in the air spring body. The changed pressure value and the current value are collected by the LMS multi-functional data acquisition system and input into the control module. According to the conditions that the air spring body pressure and magnet current for realizing near-zero stiffness need to meet, judge whether the positive and negative stiffnesses match; If not, the control module outputs a target current through the DC regulated power supply to make the regulated magnet negative stiffness mechanism adapt to the airbag positive stiffness mechanism of the current load; The magnetic hybrid quasi-zero stiffness vibration isolator includes an airbag positive stiffness mechanism and a magnet negative stiffness mechanism; The airbag positive stiffness mechanism is a single-curved airbag air spring, which includes an upper cover plate, a lower cover plate and an elastic bladder. The upper and lower cover plates are horizontally and oppositely arranged; The upper and lower ends of the elastic bladder are respectively connected to the upper and lower cover plates, and the three enclose to form a closed air spring body; The air spring body is provided with an air inlet and an air outlet, and the air inlet is connected to an external air path maintaining device; The magnet negative stiffness mechanism is installed in the air spring body, the upper end of the magnet negative stiffness mechanism is connected to the upper cover plate, and the lower end of the magnet negative stiffness mechanism is connected to the lower cover plate; The magnet negative stiffness mechanism includes a middle permanent magnet, two outer permanent magnets and two groups of electromagnets; The middle permanent magnet is vertically arranged, and its upper end is connected to the lower part of the upper cover plate through a fixing frame; The two outer permanent magnets are symmetrically arranged on both sides of the middle permanent magnet, and the same poles of adjacent permanent magnets are arranged opposite to each other; One end of the outer permanent magnet is connected to the electromagnet, and the other end of the electromagnet is fixed on the column, and the lower end of the column is connected to the lower cover plate; The electromagnet coil is connected to the DC regulated power supply to form a loop; The load adaptive control system includes a signal acquisition module, a control module and an execution module; The magnetic hybrid quasi-zero stiffness vibration isolator is respectively connected to the signal acquisition module and the execution module; The signal acquisition module and the execution module are both respectively connected to the control module; The signal acquisition module is used to detect and obtain three different types of signals of displacement, current and pressure of the magnetic hybrid quasi-zero stiffness vibration isolator as the input of the control module; The control module is used to receive the signals input by the signal acquisition module and judge whether to output control signals to the execution module; The execution module is used to receive the control signal output by the control module and output the control current and charge / discharge air to the magnetic hybrid quasi-zero stiffness vibration isolator.

2. The load adaptive control method according to claim 1, characterized in that The air spring body pressure and magnet current to achieve near-zero stiffness should satisfy the following relationship: In the above formula, F is the current load with the unit of N; P at is the atmospheric pressure with the unit of Pa; P sur0 , P0, S ef0 and V0 are respectively the gauge pressure, absolute pressure, effective load-bearing area of the bladder wall, and volume of the air spring body when the air spring body is at the rated working height H. The units of these four parameters are Pa, Pa, m 2 , m 2 ; δ z is the vertical displacement value of the vibration isolator, with the unit of m; S ef is the effective bearing area of the vibration isolator, with the unit of m 2 ; n is the polytropic index, taking 1 for the isothermal process and 1.4 for the adiabatic process; S is the cross-sectional area of the magnetic circuit, with the unit of m 2 ; δ is the air gap length, with the unit of m; N is the number of turns of the coil, with the unit of turn; I is the current intensity flowing through the coil, with the unit of A; μ0 is the magnetic permeability of vacuum, with the unit of H / m.

3. The load adaptive control method according to claim 1, wherein In step two, when the control module detects that Y > H, the control module activates the air release solenoid valve to discharge the gas in the air spring body; when Y < H, the control module activates the air inflation solenoid valve to inflate the air spring body.

4. The load adaptive control method according to claim 1, characterized in that The permanent magnet is made of neodymium iron boron material; a channel is provided in the lower cover or the upper cover, one end of the channel is connected to the air inlet of the air spring body, and the other end of the channel can be connected to an external air path holding device.

5. The load adaptive control method according to claim 4, wherein The execution module includes a DC regulated power supply and an air path holding device. The DC regulated power supply is connected to the coil of the electromagnet to form a circuit loop; the air path holding device is connected to the inside of the air spring body through a pipeline, and an air inflation solenoid valve is arranged on this pipeline; the execution module also includes an air release solenoid valve arranged at the air outlet of the air spring body.

6. The load adaptive control method according to claim 5, wherein The signal acquisition module includes a displacement sensor, a digital display ammeter, a pressure sensor, a power amplifier, and an LMS multi-functional data acquisition system. The displacement sensor is arranged on the upper surface of the upper cover; the digital display ammeter is installed on the loop connecting the electromagnet coil and the DC regulated power supply; the pressure sensor is fixed on the lower cover and is located inside the airbag positive stiffness mechanism; the displacement sensor, the digital display ammeter, and the pressure sensor are respectively connected to the input end of the power amplifier, and respectively input the measured displacement signal, current signal, and pressure signal into the power amplifier for amplification; the output end of the power amplifier is connected to the LMS multi-functional data acquisition system, and the LMS multi-functional data acquisition system is connected to the control module; the LMS multi-functional data acquisition system is used to collect the amplified signals and send the signals to the control module.

7. The load adaptive control method according to claim 6, wherein The control module includes a DSP controller. The DSP controller is respectively connected to the LMS multi-functional data acquisition system of the signal acquisition module, the DC regulated power supply, the air inflation solenoid valve, and the air release solenoid valve of the air path holding device; according to the control signal output by the control module, the execution module activates the DC regulated power supply to output the control current, controls the solenoid valve, and charges and discharges the air spring body.

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