Eddy current negative stiffness magnetorheological elastomer isolator

Abstract

The application discloses an eddy current negative stiffness magneto-rheological elastomer vibration isolator, which comprises an eddy current damping structure and a negative stiffness magneto-rheological elastomer structure, wherein the eddy current damping structure comprises a U-shaped permanent magnet and a conductor, and the U-shaped permanent magnet and the conductor are annular; the bottom of the U-shaped permanent magnet is mounted on a bottom plate; the top of the conductor is connected with a top plate, and the bottom of the conductor is mounted in the U-shaped permanent magnet to move in a cutting magnetic induction line mode; the bottom plate and the top plate are respectively mounted on a vibration source and a vibration-isolated structure; one end of the negative stiffness magneto-rheological elastomer structure is arranged in an annular inner ring of the U-shaped permanent magnet and connected with the bottom plate; and the other end of the negative stiffness magneto-rheological elastomer structure is arranged in an annular inner ring of the conductor and connected with the top plate. The application can reduce the amplitude of the vibration isolation system when passing through a resonance region, improve the relative vibration isolation effect, and prevent the vibration isolation system structure from being adversely affected due to resonance.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of vibration control, in particular to a kind of eddy current negative stiffness magnetorheological elastomer vibration isolator. BACKGROUND

[0002] Vibration phenomenon widely exists in daily life and engineering applications, and its harm cannot be underestimated. In the field of civil engineering, vibration can cause house collapse and bridge fracture. In the field of mechanical processing, vibration can cause wear of precision processing instruments and reduce processing precision. In the field of instruments and meters, vibration can cause misplacement of instrument structure and reduce measurement accuracy.

[0003] At present, common structural vibration control techniques can be divided into passive control, active control and semi-active control. Traditional passive control techniques have fixed structural design parameters, and can only effectively control external excitation with fixed amplitude and frequency, and lack of self-adaptation. Compared with passive control techniques, active control techniques can track external load characteristics and structural vibration characteristics in real time, output optimal control force, and suppress structural vibration. Active control needs a large amount of external energy to provide the required control force, and the vibration suppression effect is poor in extreme cases. Semi-active control combines the advantages of passive control and active control, and only needs small energy to achieve parameter control of vibration system, so as to effectively reduce vibration.

[0004] Magnetorheological elastomer (MRE) is a new branch of magnetorheological materials, which is solidified by high polymer (such as rubber, etc.) and ferromagnetic particles under the action of external magnetic field. MRE has the advantages of magnetorheological materials and elastomers, such as fast response, good reversibility, strong controllability, and overcomes the shortcomings of easy sedimentation and poor stability of previous magnetorheological materials. Therefore, MRE has become a research hotspot in the field of magnetorheological materials, and can be widely used in mechanical transmission, vibration isolation, robots and intelligent actuators. Under the action of controllable external magnetic field, the stiffness characteristics of magnetorheological elastomer vibration isolator can be intelligently controlled in real time, so as to change the natural frequency and vertical bearing capacity of the vibration isolation system, and to isolate the transmission of external vibration to the system to the greatest extent, and fundamentally achieve the purpose of engineering structure vibration isolation.

[0005] The stiffness of magnetorheological elastomer is positively related to the external magnetic field. Most of the designed MRE vibration isolators need to be powered all the time to ensure their large static stiffness to achieve stable bearing. However, negative stiffness magnetorheological elastomer structure can well solve the problem that positive stiffness MRE vibration isolator needs to be powered all the time without vibration, and is more suitable for actual engineering application requirements.

[0006] In addition, most of the MRE vibration isolators do not have a damping mechanism to dissipate the vibration energy brought by external excitation, only the low damping effect of the magneto-rheological elastomer material itself, which greatly affects the efficiency of the vibration isolator in restoring to a stable equilibrium state after being excited, and makes the vibration isolator in a vibration state for a long time. Traditional dampers are mainly oil dampers, and the durability of the sealing element and damping oil in the oil damper has been questioned, and the presence of the sealing element makes the friction of the oil damper larger, and under the action of reciprocating load, oil leakage phenomenon is easy to occur, and once the oil damper leaks, the damping force and damping coefficient will decrease, which no longer meets the design requirements, and the project has safety hazards. In addition, the oil damper also has a series of problems such as short service life, high maintenance cost, complex connection, low sensitivity, large starting resistance, etc. The use of eddy current damping structure can make the conductor plate cut the magnetic induction lines in the magnetic field to produce eddy current to dissipate vibration energy in the form of heat. SUMMARY

[0007] The present application solves the problems of the prior art and provides an eddy current negative stiffness magneto-rheological elastomer vibration isolator which improves the bearing capacity and ensures the vibration isolation performance.

[0008] To achieve the above-mentioned purpose, the present application first proposes an eddy current negative stiffness magneto-rheological elastomer vibration isolator, which comprises an eddy current damping structure and a negative stiffness magneto-rheological elastomer structure,

[0009] The negative stiffness magneto-rheological elastomer structure comprises a magneto-rheological elastomer 6, a plate-type permanent magnet 5, a lower support 4, an upper support 3 and an electromagnetic device; the lower support 4 corresponds to the position of the upper support 3, the upper support 3 is fixed on the top plate 1, the upper support 3 is fixed on the bottom plate 2, and the bottom plate 2 and the top plate 1 are respectively installed on the vibration source and the vibration isolation structure, the upper support 3 and the lower support 4 are fixed with the plate-type permanent magnet 5 on the opposite surfaces; the magneto-rheological elastomer 6 is installed between the two plate-type permanent magnets 5, and the magneto-rheological elastomer 6 is penetrated by the first magnetic field generated by the two plate-type permanent magnets 5, the electromagnetic device is further sleeved on the bottom plate 2 and outside the magneto-rheological elastomer 6, the second magnetic field generated by the electromagnetic device when energized also penetrates the magneto-rheological elastomer 6, and the magnetic induction lines of the first magnetic field and the second magnetic field are parallel;

[0010] The negative stiffness magneto-rheological elastomer structure is sleeved with an eddy current damping structure, one end of the eddy current damping structure is fixed on the top plate 1, and the other end is fixed on the bottom plate 2.

[0011] In the embodiment, the eddy current damping structure comprises a U-shaped permanent magnet 10 and a conductor 11, both of which are annular, the bottom of the U-shaped permanent magnet 10 is mounted on the bottom plate 2, the top of the conductor 11 is connected with the top plate 1, and the bottom is mounted in the U-shaped permanent magnet 10 to move in a cutting magnetic induction line, the upper support 3 is arranged in the annular inner ring of the conductor 11, and a gap is provided between the conductor 11 and the upper support 3; the lower support 4 is arranged in the annular inner ring of the U-shaped permanent magnet 10, and a gap is provided between the U-shaped permanent magnet 10 and the lower support 4, and the electromagnetic device is mounted in the gap between the U-shaped permanent magnet 10 and the lower support 4.

[0012] In the embodiment, the negative stiffness magneto-rheological elastomer structure comprises a magneto-rheological elastomer 6, a plate-shaped permanent magnet 5, a lower support 4, an upper support 3, a coil support 8 and a coil; the upper support 3 is fixed on the top plate, the lower support 4 is correspondingly arranged opposite to the upper support 3, the upper support 3 is arranged in the annular inner ring of the conductor 11, and a gap is provided between the conductor 11 and the upper support 3; the lower support 4 is arranged in the annular inner ring of the U-shaped permanent magnet 10, and a gap is provided between the U-shaped permanent magnet 10 and the lower support 4, and the electromagnetic device is mounted in the gap between the U-shaped permanent magnet 10 and the lower support 4; the plate-shaped permanent magnets 5 are fixed on the opposite surfaces of the upper support 3 and the lower support 4; the magneto-rheological elastomer 6 is mounted between the two plate-shaped permanent magnets 5, and the magneto-rheological elastomer 6 is penetrated by a first magnetic field generated by the two plate-shaped permanent magnets 5, and a second magnetic field generated by the electromagnetic device also penetrates the magneto-rheological elastomer 6, and the magnetic induction lines of the first magnetic field and the second magnetic field are parallel.

[0013] In the embodiment, the electromagnetic device comprises a coil support 8 fixed between the U-shaped permanent magnet 10 and the lower support 4, the coil is annular, and the height of the coil support 8 covers the magneto-rheological elastomer 6 and the two plate-shaped permanent magnets 5; the coil is wound in the inner cavity of the coil support 8, and a magnetic separation sleeve 7 is further sleeved between the coil support 8 and the U-shaped permanent magnet 10, and the magnetic separation sleeve 7 is made of a magnetic separation material.

[0014] In the embodiment, the intelligent control system further comprises a displacement sensor 13 mounted on the bottom plate 2, an error sensor mounted on the top plate 1, a PID controller 14 and a current controller 15, the displacement sensor 13, the error sensor and the current controller 15 are connected with the PID controller 14 through data lines to realize information transmission, and the current controller 15 is electrically connected with the coil.

[0015] In the embodiment, the displacement sensor 13 is used for measuring the displacement vibration state x(t) of the vibration isolator bottom plate 2, and transmitting the detected vibration signal to the PID controller 14;

[0016] The error sensor is used to obtain the controlled vibration displacement state y(t) and transmit the detected vibration signal to the PID controller 14;

[0017] The PID controller 14 analyzes and processes the received vibration signal based on the PID control principle, finally obtains the output current value that can make the isolation performance of the isolator better, and transmits the information to the current controller 15, and finally realizes the current size loading of the coil by the current controller 15.

[0018] In the embodiment, the magnetic induction lines of the magnetic field generated by the U-shaped permanent magnet 10 vertically pass through the conductor 11.

[0019] In the embodiment, the lower end surface of the upper support 3 and the upper end surface of the lower support 4 have buckles matched with the size of the plate-shaped permanent magnet 5, and the two plate-shaped permanent magnets 5 are respectively fixedly connected with the upper support 3 and the lower support 4 through the buckles.

[0020] In the embodiment, the magneto-rheological elastomer 6 is prepared by mixing silicon rubber, carbonyl iron powder and dimethyl silicone oil in a ratio of 7:2:1 under the condition of an applied magnetic field.

[0021] In the embodiment, the top plate 1, the bottom plate 2, the upper support 3 and the lower support 4 are all made of magnetic conductive material, the coil support 8 is made of non-magnetic conductive material, and the magnetic shielding sleeve 7 and the outer sleeve 12 are both made of magnetic shielding material silicon steel sheet.

[0022] In the embodiment, the unlike poles of the two plate-shaped permanent magnets 5 are directed to the side of the magneto-rheological elastomer 6, so that the generated magnetic induction lines vertically pass through the magneto-rheological elastomer 6.

[0023] Compared with the prior art, the present application has the following advantages:

[0024] The technical innovation of the present application and the good effect are that:

[0025] (1) The isolator body of the present application is provided with appropriate damping by the external electric eddy current damping structure, so that the damping ratio ζ increases, so that T dThe closer to 1, thereby reducing the amplitude of the vibration isolation system through the resonance zone, improving the relative isolation effect, to prevent the vibration isolation system structure from resonance effect produces adverse effects; and the eddy current damping structure is provided by the relative motion between the U-shaped permanent magnet and the conductor structure The eddy current generated by the eddy current damping provides the eddy current damping, since the conductor does not contact the U-shaped permanent magnet, which is an ideal damping mode without friction and wear, and does not produce a series of problems caused by oil damping due to sealing, reduces the consumption of energy, and cooperates with the plate-shaped permanent magnet, further prevent the electric energy loss and heat generated by the coil frequently working. By combining the eddy current damping structure with the negative stiffness magneto-rheological elastomer structure, the problem of poor damping energy consumption effect of the traditional negative stiffness magneto-rheological elastomer structure due to the lack of additional damping structure is solved, and the vibration isolation capacity of the negative stiffness magneto-rheological elastomer structure is greatly increased.

[0026] (2) The present application is provided with a plate-shaped permanent magnet, which can provide the magneto-rheological elastomer with a certain initial stiffness, thereby improving the bearing capacity, and can also save electric energy without consuming energy, and prevent the coil from working at a high frequency and generating a large amount of heat.

[0027] (3) The present application further comprises an intelligent control system, which comprises an intelligent module of the vibration isolator through a displacement sensor, a PID controller, a current controller and a corresponding PID control algorithm, the PID controller can quickly respond to changes in the controlled system according to the actual feedback information of the controlled system, and can adjust the control amount in real time, thereby maintaining the stability, accuracy and real-time performance of the controlled system, thereby realizing optimal control and ensuring that the vibration isolator can always exhibit excellent vibration isolation performance in operation. BRIEF DESCRIPTION OF DRAWINGS

[0028] Figure 1 is a three-dimensional cross-sectional schematic view of the present application.

[0029] Figure 2 is a three-dimensional cross-sectional schematic view of the eddy current damping structure of the present application.

[0030] Figure 3 is a three-dimensional cross-sectional schematic view of the negative stiffness magneto-rheological elastomer structure of the present application.

[0031] Figure 4 is a PID control flowchart of the present application.

[0032] Figure 5 is a graph of the relationship between the absolute motion transmissibility and the frequency ratio of the present application.

[0033] Wherein, 1, top plate; 2, bottom plate; 3, upper support; 4, lower support; 5, plate type permanent magnet; 6, magnetorheological elastomer; 7, magnetic isolation sleeve; 8, coil support; 9, coil; 10, U-shaped permanent magnet; 11, conductor; 12, outer sleeve; 13, displacement sensor; 14, PID controller; 15, current controller. DETAILED DESCRIPTION

[0034] The technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative work are within the protection scope of the present application.

[0035] In addition, the technical solutions of various embodiments of the present application can be combined with each other, but it must be based on the fact that a person skilled in the art can realize it. When the combination of technical solutions appears contradictory or unachievable, it should be considered that the combination of technical solutions does not exist and is not within the protection scope required by the present application.

[0036] In combination Figures 1 to 3 , the eddy current negative stiffness magnetorheological elastomer vibration isolator of the present application comprises a vibration isolator body, the vibration isolator body comprises an eddy current damping structure, a negative stiffness magnetorheological elastomer structure and an intelligent control system, the bottom of the eddy current damping structure is installed on the bottom plate 2, the top of the negative stiffness magnetorheological elastomer structure is installed on the top plate 1, the negative stiffness magnetorheological elastomer structure is coaxially nested with the eddy current damping structure, and the eddy current damping structure and the negative stiffness magnetorheological elastomer structure are installed between the vibration source and the vibration-isolated structure through the bottom plate 2 and the top plate 1 respectively, so as to reduce the transmission of vibration energy and the response of the vibration-isolated structure to vibration excitation.

[0037] The core element of the eddy current damping structure is a U-shaped permanent magnet 10 and a conductor 11, the U-shaped permanent magnet 10 is fixed on the bottom plate 2, and the conductor 11 is connected with the lower end of the top plate 1; the U-shaped permanent magnet 10 and the conductor 11 are both circular rings, the opening of the U-shaped permanent magnet 10 faces upward, the opening of the U-shaped permanent magnet 10 corresponds to the position of the conductor 11, the conductor 11 is coaxially inserted into the opening of the U-shaped permanent magnet 10, the conductor 11 makes a cutting magnetic induction line motion in the U-shaped permanent magnet 10, the bottom plate 2 and the top plate 1 are installed on the vibration source and the vibration-isolated structure respectively, one end of the negative stiffness magnetorheological elastomer structure is arranged in the annular inner circle of the U-shaped permanent magnet 10 and connected with the bottom plate 2, and the other end is arranged in the annular inner circle of the conductor 11 and connected with the top plate 1.

[0038] The negative stiffness magneto-rheological elastomer structure comprises a magneto-rheological elastomer 6, a plate-shaped permanent magnet 5, a lower support 4, an upper support 3, a coil support 8 and a coil 9; the coil support 8 is annular and coaxially arranged in the annular inner ring of the U-shaped permanent magnet 10, the lower end of the coil support 8 is fixedly connected with the bottom plate 2, the upper support 3, the plate-shaped permanent magnet 5, the magneto-rheological elastomer 6 and the lower support 4 are coaxially installed in the annular inner ring of the coil support 8; the coil 9 is wound on the outer side of the coil support 8, and a magnetic isolation sleeve 7 is sleeved on the outer side of the coil 9, so as to separate the coil 9 and the U-shaped permanent magnet 10 in space structure, and isolate the mutual influence of the magnetic field between the two structures, the upper support 3 is installed at the lower end of the top plate 1, the lower support 4 is fixed on the bottom plate 2, the plate-shaped permanent magnet 5 is installed on the opposite side of the upper support 3 and the lower support 4, the magneto-rheological elastomer 6 is located between the pair of plate-shaped permanent magnets 5, and the magnetic field generated by the plate-shaped permanent magnet 5 penetrates the magneto-rheological elastomer 6, so that the magneto-rheological elastomer 6 has a certain initial stiffness;

[0039] As shown in Figure 4 The intelligent control system comprises a displacement sensor 13 installed on the bottom plate 2, an error sensor installed on the top plate, a PID controller 14 and a current controller 15, the displacement sensor 13, the error sensor, the current controller 15 are connected with the PID controller 14 through data lines to realize information transmission;

[0040] The displacement sensor 13 is used for measuring the displacement vibration state x(t) of the vibration isolator bottom plate, and transmitting the detected vibration signal to the PID controller 14;

[0041] The error sensor is used for obtaining the controlled vibration displacement state y(t), and transmitting the detected vibration signal to the PID controller 14;

[0042] The PID controller 14 analyzes and processes the received vibration signal based on the PID control principle, finally obtains the output current value which can make the vibration isolation performance of the vibration isolator better, and transmits this information to the current controller 15, and finally realizes the current size loading of the coil 9 by the current controller 15, and the specific control method is the prior art, which will not be described here.

[0043] In this embodiment, the top plate 1, the bottom plate 2, the upper support 3 and the lower support 4 are made of magnetically conductive material (such as pure iron for electrical engineering) for forming a magnetic conductive loop of the vibration isolator body; in order not to destroy the magnetic field concentrated on the magnetorheological elastomer 6, the coil support is made of non-magnetic conductive material; the plate-shaped permanent magnet 5 and the U-shaped permanent magnet 10 are made of rhenium boron permanent magnet; the coil 9 is wound with polyester enameled copper wire commonly used in motor coils. The conductor 11 is made of copper, which cooperates to form a magnetic conductive loop and generate an eddy current effect; the magnetic isolation sleeve 7 and the outer sleeve 12 are made of silicon steel sheet. The magnetic isolation sleeve 7 can prevent the magnetic field generated by the U-shaped permanent magnet from interfering with the magnetic field at the structure of the negative stiffness magnetorheological elastomer, and also plays a role in preventing magnetic leakage to increase the magnetic utilization rate of the magnetic field generated by the plate-shaped permanent magnet and the coil 9. The outer sleeve 12 has a similar effect to the magnetic isolation sleeve 7, which can prevent the magnetic leakage of the vibration isolator body, increase the magnetic utilization rate of the eddy current damping structure, ensure the efficient generation of the eddy current effect, and make the vibration isolator body have sufficient damping force to maintain the performance of vibration damping dissipation.

[0044] The magnetorheological elastomer 6 can be prepared by mixing silicon rubber, carbonyl iron powder and dimethyl silicone oil in a ratio of 7:2:1 under an applied magnetic field. Compared with the field-free condition, the magnetorheological elastomer prepared under the field condition has higher magnetorheological effect.

[0045] The lower end surface of the upper support 3 and the upper end surface of the lower support 4 have buckles matching the size of the plate-shaped permanent magnet 5 to prevent the plate-shaped permanent magnet 5 from falling off between the upper support 3 and the lower support 4.

[0046] The plate-shaped permanent magnet 5 has two pieces connected to the upper and lower end surfaces of the magnetorheological elastomer 6. The unlike poles of the two plate-shaped permanent magnets 5 face the side of the magnetorheological elastomer 6. Due to the magnetic induction line distribution characteristic that the N pole flows into the S pole, the generated magnetic induction line vertically penetrates the magnetorheological elastomer 6, and is approximately parallel to the internal magnetic field generated when the coil 9 is energized.

[0047] The stiffness characteristic of the magnetorheological elastomer 6 is positively correlated with the magnetic field strength around it, so the bias magnetic field generated by the plate-shaped permanent magnet 5 makes the vibration isolator body have a certain initial stiffness. When the coil 9 is energized, the magnetic field generated by the coil 9 superimposes or cancels the bias magnetic field, increasing or decreasing the magnetic field strength acting on the magnetorheological elastomer 6, thereby changing the stiffness characteristic of the vibration isolator body and achieving the purpose of negative stiffness.

[0048] One side of the U-shaped permanent magnet 10 is N pole and the other side is S pole. The magnetic induction line of the magnetic field generated by the U-shaped permanent magnet 10 approximately vertically penetrates the conductor 11, so that the conductor 11 can have a larger eddy current effect when it moves to cut the magnetic induction line.

[0049] The electric eddy current generated damping vibration reduction energy consumption and the magnetic rheological elastomer variable stiffness vibration isolation amplitude reduction are combined, the information acquisition of the vibration of the vibration isolator body by the displacement sensor 13 and the optimization of the output current by the PID control algorithm are matched, and the intelligent vibration reduction and isolation purposes of high efficiency, stability and precision are realized.

[0050] The working process of the application and the principle of the control system thereof are as follows:

[0051] 1、When the vibration isolator body is subjected to external excitation, the conductor will move in the magnetic field generated by the U-shaped permanent magnet, the magnetic flux in the conductor changes, and according to the principle of electromagnetic induction, an induced current is immediately generated in the conductor, and an electric eddy current is automatically formed in the plate. The electric eddy current magnetic field generated by the electric eddy current interacts with the original magnetic field, and a force that hinders the movement of the conductor plate, i.e. the electric eddy current damping force, is generated. In this process, the kinetic energy of the relative movement of the conductor and the magnetic field is first converted into electric energy, and then into heat energy in the conductor and dissipated, thus playing a role in energy dissipation and vibration reduction.

[0052] 2、When the vibration isolator body is subjected to external excitation and generates vibration, the magnetic rheological elastomer, as a kind of rubber-like material, has good elasticity and can absorb and disperse vibration energy. When the vibration is transmitted to the magnetic rheological elastomer, the magnetic rheological elastomer will deform, and the change of the chain structure of the interlaced molecules of the magnetic rheological elastomer will absorb and disperse the vibration energy; the molecules in the magnetic rheological elastomer have strong friction between them, and the friction will convert the vibration energy into internal heat energy, thereby reducing the transmission of vibration.

[0053] The magnetic rheological effect of the magnetic rheological elastomer is the key to its good vibration isolation performance. When an external magnetic field acts on the magnetic rheological material, the magnetic particles in the material will arrange into a chain structure to form a magnetic field network, thereby changing the stiffness and damping properties of the material. This magnetic field network can make the magnetic rheological elastomer more effectively absorb and disperse mechanical vibration energy, thereby achieving the effect of vibration isolation.

[0054] Through the plate-type permanent magnet, the bias magnetic field generated thereby acts on the magnetic rheological elastomer, so that the magnetic rheological elastomer can have a certain initial stiffness when the coil is not electrified, so that the vibration isolator body has a certain bearing capacity and stability without current.

[0055] Moreover, the direction of the bias magnetic field generated by the plate-type permanent magnet is opposite to the direction of the magnetic field generated when the coil is electrified with a forward current; when the coil is electrified with a forward current, the magnetic field generated thereby and the bias magnetic field cancel each other out, reducing the magnetic field strength acting on the magnetic rheological elastomer, and further reducing the stiffness of the magnetic rheological elastomer;

[0056] When the coil passes negative current, the magnetic field generated by the coil and the bias magnetic field superimpose each other, increasing the magnetic field strength acting on the magneto-rheological elastomer, and further increasing the stiffness of the magneto-rheological elastomer; by controlling the direction and size of the coil current, the natural frequency of the vibration isolator body can be changed in real time.

[0057] The negative stiffness magneto-rheological elastomer structure can well solve the problems of power waste and coil heating caused by the positive variable stiffness MRE vibration isolator needing to be powered all the time without vibration.

[0058] The vibration isolation benefits of the electric eddy current damping structure and the negative stiffness magneto-rheological elastomer structure working together are specifically analyzed:

[0059] The vibration isolator body is used to reduce the transmission of external vibration excitation to the isolated structure. When the vibration isolator body is subjected to external vibration excitation, the vibration isolation system (composed of the vibration isolator body and the isolated structure) will do forced vibration under the action of external excitation. The absolute motion transmissibility of the forced vibration is T d :

[0060]

[0061] Wherein, ζ is the damping ratio, C is the damping of the system composed of the vibration isolator body and the building structure, C c is the critical damping, r is the frequency ratio, ω is the frequency of external excitation, ω n is the natural frequency of the system composed of the vibration isolator body and the building structure.

[0062] The relationship between the absolute motion transmissibility and the frequency ratio is shown in the graph as Figure 5 .

[0063] From Figure 5 and the formula, it can be known that when , T d tends to 0, indicating that the motion transmitted by the vibration isolator body is isolated by the vibration isolator body, and the vibration isolation effect is good. It can be known from that wherein k is the stiffness, and m is the mass. Reducing the stiffness k will reduce the natural frequency ω n , and the value of the frequency ratio r will increase. When the value of r is far greater than , T d tends to 0, and the vibration isolation effect is better.

[0064] However, the vibration excitation frequency of the vibration isolator body is not constant in the actual application process, and may contain vibrations of multiple frequencies. These frequency vibrations will cause the vibration isolation system to resonate, such as Figure 5 , when At this point, the resonance region is reached, and the larger the damping ratio ζ is, the greater the T value. d The closer it is to 1, the better the vibration isolation effect.

[0065] Therefore, the vibration isolator body of this application is equipped with appropriate damping by adding an external eddy current damping structure, thereby increasing the damping ratio ζ. When the resonance region is reached, T d The closer it is to 1, the smaller the amplitude of the vibration isolation system when passing through the resonance zone, thus improving the relative vibration isolation effect. Therefore, the vibration isolator body combines the eddy current damping structure and the negative stiffness magnetorheological elastomer structure to ensure that the amplitude of the vibration isolation system when passing through the resonance zone is as small as possible, and to prevent the adverse effects of resonance on the structure of the vibration isolation system.

[0066] The principle of negative stiffness in this application is as follows: This application sets up a plate-type permanent magnet to realize a fixed initial magnetic field. This initial magnetic field is canceled out as the positive current in the coil increases, thereby reducing the magnetic field inside the negative stiffness magnetorheological elastomer structure.

[0067] When the negative stiffness magnetorheological elastomer structure is not subjected to external excitation (no external vibration occurs), no current flows through the coil. Under the action of the bias magnetic field (generated by the plate permanent magnet), the magnetorheological elastomer has a large stiffness, giving the vibration isolator body a high initial stiffness. When the vibration isolator body is subjected to external random excitation, due to vibration isolation requirements, a certain positive current is passed through the coil to induce a corresponding magnetic current around the magnetorheological elastomer. The induced magnetic field cancels out the bias magnetic field, and as the current increases, the magnetic field around the magnetorheological elastomer gradually disappears until it becomes zero. At this point, the stiffness and damping of the magnetorheological elastomer are at their minimum. During the transition from the non-isolation state to the above-mentioned isolation state, the stiffness of the vibration isolator body changes from large to small. In this transition process, the frequency ratio r changes from the resonance range to the isolation range. The transformation (such as) Figure 5 As shown in the figure, the smaller the damping ratio within this range, the better the vibration isolation effect. In the transformation process of this invention, the damping gradually decreases, which just meets the vibration isolation requirements.

[0068] In summary, the combination of eddy current damping structure and negative stiffness magnetorheological elastomer structure in the vibration isolator body not only solves the problem of energy waste and coil heating caused by the need to keep the vibration isolator body energized when it is not working in order to ensure the load-bearing capacity of the vibration isolator body, but also has better vibration isolation performance than ordinary magnetorheological elastomer vibration isolators in the process of achieving vibration isolation control.

[0069] The above merely illustrates the preferred embodiments of the present application, and is not intended to limit the patent scope of the present application, and any equivalent structural transformation, direct / indirect application in other related technical fields, or the like, which are made under the concept of the present application, and based on the content of the present application specification and drawings, are included in the patent protection scope of the present application.

Claims

1. An eddy current negative stiffness magnetorheological elastomer vibration isolator, characterized in that: The electric eddy current damping structure and the negative stiffness magneto-rheological elastomer structure are included. The negative stiffness magneto-rheological elastomer structure includes a magneto-rheological elastomer (6), a plate-shaped permanent magnet (5), a lower support (4), an upper support (3) and an electromagnetic device; the lower support (4) corresponds to the upper support (3) in position, the upper support (3) is fixed on the top plate (1), the upper support (3) is fixed on the bottom plate (2), the bottom plate (2) and the top plate (1) are respectively installed on a vibration source and a vibration-isolated structure, the upper support (3) and the lower support (4) are both fixed with the plate-shaped permanent magnet (5) on the opposite surfaces; the magneto-rheological elastomer (6) is installed between the two plate-shaped permanent magnets (5), and the magneto-rheological elastomer (6) is penetrated by a first magnetic field generated by the two plate-shaped permanent magnets (5), the electromagnetic device is further sleeved on the bottom plate (2) and outside the magneto-rheological elastomer (6), a second magnetic field generated by the electromagnetic device when energized also penetrates the magneto-rheological elastomer (6), and the magnetic induction lines of the first magnetic field and the second magnetic field are parallel; The negative stiffness magneto-rheological elastomer structure is further sleeved with the electric eddy current damping structure, one end of the electric eddy current damping structure is fixed on the top plate (1), and the other end is fixed on the bottom plate (2); The electric eddy current damping structure includes a U-shaped permanent magnet (10) and a conductor (11), the U-shaped permanent magnet (10) and the conductor (11) are both annular, the bottom of the U-shaped permanent magnet (10) is installed on the bottom plate (2), the top of the conductor (11) is connected with the top plate (1), and the bottom is installed in the U-shaped permanent magnet (10) to make a cutting magnetic induction line movement, the upper support (3) is arranged in the annular inner ring of the conductor (11), and a gap is arranged between the conductor (11) and the upper support (3); the lower support (4) is arranged in the annular inner ring of the U-shaped permanent magnet (10), and a gap is arranged between the U-shaped permanent magnet (10) and the lower support (4), and the electromagnetic device is installed in the gap between the U-shaped permanent magnet (10) and the upper and lower supports.

2. The eddy current negative stiffness magnetorheological elastomer vibration isolator of claim 1, wherein: The electromagnetic device includes a coil support (8) fixed between the U-shaped permanent magnet (10) and the lower support (4), the coil is annular, the height of the coil support (8) covers the magneto-rheological elastomer (6) and the two plate-shaped permanent magnets (5); a coil is wound in the inner cavity of the coil support (8), and a magnetic separation sleeve (7) is further sleeved between the coil support (8) and the U-shaped permanent magnet (10), and the magnetic separation sleeve (7) is made of a magnetic separation material.

3. The eddy current negative stiffness magnetorheological elastomer vibration isolator of claim 2, wherein: An intelligent control system is further included, the intelligent control system includes a displacement sensor (13) installed on the bottom plate (2), an error sensor installed on the top plate (1), a PID controller (14) and a current controller (15), the displacement sensor (13), the error sensor, the current controller (15) are connected with the PID controller (14) through data lines to realize information transmission, and the current controller (15) is electrically connected with the coil.

4. The eddy current negative stiffness magnetorheological elastomer vibration isolator of claim 3, wherein: The displacement sensor (13) is used for measuring the displacement vibration state x(t) of the vibration isolator bottom plate (2), and transmitting the detected vibration signal to the PID controller (14); The error sensor is used to obtain the controlled vibration displacement state y(t) and transmit the detected vibration signal to the PID controller (14); The PID controller (14) analyzes and processes the received vibration signal based on the PID control principle, finally obtains the output current value that can make the isolator have better isolation performance, and transmits the information to the current controller (15), and finally realizes the current size loading of the coil by the current controller (15).

5. The eddy current negative stiffness magnetorheological elastomer vibration isolator of claim 1, wherein: The magnetic induction lines of the magnetic field generated by the U-shaped permanent magnet (10) are perpendicular to the conductor (11).

6. The eddy current negative stiffness magnetorheological elastomer vibration isolator according to any one of claims 1 to 5, characterized in that: The lower end surface of the upper support (3) and the upper end surface of the lower support (4) have buckles matched with the size of the plate-shaped permanent magnet (5), and the two plate-shaped permanent magnets (5) are fixedly connected with the upper support (3) and the lower support (4) through the buckles respectively.

7. The eddy current negative stiffness magnetorheological elastomer vibration isolator of claim 6, wherein: The top plate (1), the bottom plate (2), the upper support (3) and the lower support (4) are all made of magnetically conductive material, the coil support (8) is made of non-magnetic conductive material, and the magnetic isolation sleeve (7) and the outer sleeve (12) are both made of magnetic isolation material silicon steel sheet.

8. The eddy current negative stiffness magnetorheological elastomer vibration isolator of claim 6, wherein: The unlike poles of the two plate-shaped permanent magnets (5) face the side of the magnetorheological elastomer (6), so that the generated magnetic induction lines are perpendicular to the magnetorheological elastomer (6).

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