A novel combined vibration damping device with adjustable stiffness and damping

Abstract

The present invention discloses a novel combined vibration damping device with adjustable stiffness and damping, which relates to the technical field of vibration damping; it includes a magneto-resistive stress negative stiffness spring located inside the housing and a piezoelectric friction assembly located inside the bearing seat; a central shaft is connected between the two, and a metal helical spring is sleeved outside the central shaft. The bottom of the metal helical spring is connected to a spring base located at the top of the housing, and the top of the metal helical spring is connected to the bottom of the bearing seat; the central shaft is fixedly connected to the top inside the housing through a metal cross leaf spring. The magneto-resistive stress negative stiffness spring and the metal cross leaf spring can be connected in parallel to achieve the adjustment of quasi-zero stiffness, and the piezoelectric friction assembly can achieve the adjustment of damping; a load platform is fixedly arranged at the top of the bearing seat. The present invention has non-linear frequency-varying characteristics of high static stiffness - low dynamic stiffness, large low-frequency damping - small high-frequency damping, and can well solve the contradiction between the bearing capacity and the vibration damping frequency band, as well as the contradiction between high-frequency and low-frequency vibration attenuation, and achieve high-performance vibration damping.

Description

Technical Field

[0001] The present invention relates to the technical field of vibration damping, and particularly to a novel combined vibration damping device with adjustable stiffness and damping. Background Art

[0002] In the field of vibration damping, important indicators for measuring the performance of a vibration damping device are the vibration damping frequency band and the vibration attenuation rate. Commonly used linear vibration damping devices in engineering mainly use elastic elements and damping elements with fixed parameters to achieve vibration damping for the controlled object. Among them, reducing the stiffness can lower the natural frequency of the system and expand the vibration damping frequency band, but it will cause excessive static deformation and reduced load-bearing capacity; increasing the damping can reduce the resonance peak near the natural frequency, but at the same time it will reduce the high-frequency vibration attenuation rate; and once the stiffness and damping parameters of the linear vibration damping device are determined, its applicable range is fixed, so it is only effective within a certain frequency range and has weak environmental adaptability.

[0003] With the continuous improvement of processing and measurement accuracy in modern industry, the above-mentioned traditional vibration damping devices can no longer meet the vibration damping requirements in specific situations. There is an urgent need in engineering to develop a novel combined vibration damping device with adjustable stiffness and damping, which has non-linear frequency-varying characteristics of high static stiffness - low dynamic stiffness, large low-frequency damping - small high-frequency damping, so as to solve the contradiction between the load-bearing capacity and the vibration damping frequency band, as well as the contradiction between high-frequency and low-frequency vibration attenuation, and achieve high-performance vibration damping. Summary of the Invention

[0004] The purpose of the present invention is to provide a novel combined vibration damping device with adjustable stiffness and damping, so as to solve the problems existing in the above-mentioned prior art, having non-linear frequency-varying characteristics of high static stiffness - low dynamic stiffness, large low-frequency damping - small high-frequency damping, which can well solve the contradiction between the load-bearing capacity and the vibration damping frequency band, as well as the contradiction between high-frequency and low-frequency vibration attenuation, and achieve high-performance vibration damping.

[0005] To achieve the above purpose, the present invention provides the following solution:

[0006] The present invention provides a novel combined vibration damping device with adjustable stiffness and damping, which includes a magnetoresistive stress negative stiffness spring located inside a housing and a piezoelectric friction assembly located inside a bearing seat; a central shaft is connected between the magnetoresistive stress negative stiffness spring and the piezoelectric friction assembly, a metal helical spring is sleeved outside the central shaft, the bottom of the metal helical spring is fixedly connected to a spring base located at the top of the housing, and the top of the metal helical spring is connected to the bottom of the bearing seat; the central shaft is fixedly connected to the top inside the housing through a metal cross leaf spring; a load platform is fixedly arranged at the top of the bearing seat. The present invention integrates the vibration damping technologies of realizing adjustable quasi-zero stiffness by the parallel connection of a novel Maxwell magnetoresistive stress negative stiffness spring and a metal cross leaf spring and realizing adjustable frequency-varying damping by a system multi-parameter model and a mechanical wedge lever type piezoelectric friction assembly, can achieve the purpose of adjustable stiffness and damping, reduce the natural frequency and the peak value of the resonance peak of the system, and at the same time ensure the high attenuation of high-frequency vibration, and realize high-performance vibration damping in a relatively wide working frequency band. The novel Maxwell magnetoresistive stress negative stiffness spring uses the change of magnetoresistance in a magnetic circuit to generate Maxwell normal magnetic stress to achieve the purpose of generating negative stiffness. Compared with the traditional method of using the attraction or repulsion of magnets to realize the negative stiffness characteristic, it can provide greater negative stiffness under the same volume. The mechanical wedge lever type piezoelectric friction assembly adopts the method of pre-tightening with a wedge block, and uses a mechanical lever type stroke amplification mechanism to amplify the micro-displacement of a piezoelectric ceramic actuator, and then drives the friction surface of the amplification mechanism to clamp a high-stiffness friction part inward, bringing friction damping to the system, and its magnitude can be adjusted by changing the driving voltage of the piezoelectric ceramic actuator. In practical engineering applications, the vibration damping device provided by the present invention can actively adjust the stiffness parameter and damping parameter of the vibration damping device according to the real-time working conditions, and achieve the best vibration damping effect by reasonably selecting the values of the stiffness and damping parameters.

[0007] Optionally, the housing includes an upper housing and a lower housing fixedly connected, the outer end of the metal cross leaf spring is installed on the upper housing through bolts, and the inner end of the metal cross leaf spring is fixed on the shoulder of the central shaft through a fastening nut; the spring base is fixedly connected to the top of the upper housing.

[0008] Optionally, the magnetoresistive stress negative stiffness spring includes an upper stator, a holder, and a lower stator that are coaxially arranged from top to bottom in sequence; a plurality of mounting grooves are evenly arranged inside the holder, permanent magnets are arranged in the mounting grooves, and the polarities of all the permanent magnets are the same in the radial direction; a mover is coaxially arranged inside the cavity formed by the upper stator, the lower stator, and the holder, the mover has gaps with the upper stator and the lower stator in the axial direction respectively, and the mover has a gap with the permanent magnets in the radial direction; the mover is fixed to the central shaft by threads. The novel Maxwell magnetoresistive stress negative stiffness spring in the damping device provided by the present invention utilizes the change of magnetoresistance in the magnetic circuit to generate Maxwell normal magnetic stress to achieve the purpose of generating negative stiffness, and at the same time has the advantages of high magnetic negative stiffness, small volume, and light weight. When the mover is at the equilibrium position, the air gaps between the mover and the upper and lower stators are the same, the magnetoresistance in the magnetic circuit is the same, and the acting force is zero; when the mover deviates from the equilibrium position due to vibration, the air gaps between the mover and the upper and lower stators are different, resulting in different magnetoresistances in the upper and lower magnetic circuits, and then different Maxwell normal magnetic stresses are generated on the upper and lower surfaces of the mover, and the direction of the magnetic force generated is the same as the direction of the displacement deviation, showing the characteristics of negative stiffness. The magnitude of the Maxwell normal magnetic stress is related to key factors such as the initial gap, magnetic field strength, and magnetic circuit permeability. The present invention can conveniently and controllably adjust the magnitude of the negative stiffness in the device by means of changing the initial gap between the mover and the permanent magnets, the upper and lower stators, or replacing the permanent magnets with electromagnetic coils and applying a controllable current to the electromagnetic coils.

[0009] Optionally, the piezoelectric friction assembly includes a mechanical lever type stroke amplification mechanism. The mechanical lever type stroke amplification mechanism includes a first part and a second part which are symmetrically arranged. A third part and a fourth part are symmetrically arranged between the first part and the second part. The first part and the second part are connected by a flexible hinge. The extension part between the second part and the third part is connected by a flexible hinge. The third part and the fourth part are connected by a flexible hinge. The tops of the first part and the second part are fixedly connected to the load platform by bolts. A pre-tightening spring baffle is connected above the first part and the second part by a pre-tightening bolt. Two pre-tightening springs are respectively connected to the bottom of the pre-tightening spring baffle to two wedge blocks. A piezoelectric ceramic actuator is arranged between the two wedge blocks. The displacement output end of the piezoelectric ceramic actuator is fixedly connected to the wedge block by solid glue. Wedge surfaces are arranged on the inner sides of the third part and the fourth part above the extension part. The wedge block is in contact and cooperation with the wedge surface of the third part or the fourth part through the wedge surface at the end away from the piezoelectric ceramic actuator. A high-rigidity friction member is arranged between the third part and the fourth part. The high-rigidity friction member is located below the extension part, and the bottom of the high-rigidity friction member is connected to the upper end of the central shaft through a threaded hole. In the mechanical wedge lever type piezoelectric friction assembly of the vibration damping device provided by the present invention, pre-tightening is carried out by the way of wedge blocks plus pre-tightening springs, and an external electric field is used to control the piezoelectric ceramic actuator to generate a micro displacement. The micro displacement drives the friction surfaces on both sides of the other end to clamp the high-rigidity friction member inward through the amplification of the mechanical lever type stroke amplification mechanism. When the system vibrates, friction force is generated by the relative movement between the high-rigidity friction member and the friction surface of the mechanical lever type stroke amplification mechanism, thereby consuming the vibration energy of the system and providing friction damping for the system. By controlling the magnitude of the driving voltage of the piezoelectric ceramic actuator, active adjustment of the friction damping can be achieved.

[0010] Optionally, a linear bearing is arranged at the bottom of the bearing seat. The central shaft passes through the linear bearing upward and is connected to the piezoelectric friction assembly.

[0011] Optionally, a guide plate is fixedly installed in the lower shell by bolts. The bottom of the central shaft penetrates through the guide plate.

[0012] The present invention has achieved the following technical effects compared with the prior art:

[0013] The novel combined vibration damping device with adjustable stiffness and damping provided by the present invention is applied to the field of vibration damping, and can actively adjust the stiffness parameter and damping parameter of the vibration damping device according to the real-time working condition, so as to achieve high-performance vibration damping.

[0014] Specifically, the present invention has the following technical characteristics:

[0015] (1) A novel combined vibration damping device with adjustable stiffness and damping provided by the present invention combines the vibration damping technologies of realizing adjustable quasi-zero stiffness by paralleling a novel Maxwell magnetoresistive stress negative stiffness spring and a metal cross-spring, and realizing adjustable frequency-variable damping based on a system multi-parameter model and a mechanical wedge-lever type piezoelectric friction component, to form a novel vibration damping device with adjustable stiffness and damping, which can reduce the natural frequency and the peak value of the resonance peak of the system, while ensuring high attenuation of high-frequency vibration, and realizing high-performance vibration damping in a relatively wide working frequency band.

[0016] (2) The novel Maxwell magnetoresistive stress negative stiffness spring in the present invention uses the change of magnetoresistance in the magnetic circuit to generate Maxwell normal magnetic stress to achieve the purpose of generating negative stiffness. Compared with the traditional method of using the attraction or repulsion of magnets to achieve negative stiffness characteristics, it can provide greater negative stiffness under the same volume. The present invention can conveniently and controllably adjust the negative stiffness characteristics of the magnetic negative stiffness spring by means of changing the initial gaps between the mover and the permanent magnet, the upper and lower stators, or replacing the permanent magnet with an electromagnetic coil and applying a controllable current to the electromagnetic coil. The magnetic negative stiffness spring in the present invention has the advantages of compact structure, large adjustable range and linear range of magnetic negative stiffness.

[0017] (3) The adjustable stiffness characteristic of the vibration damping device provided by the present invention is realized by paralleling the novel Maxwell magnetoresistive stress negative stiffness spring and the metal cross-spring. The magnetic negative stiffness spring is prone to instability, and paralleling with the metal cross-spring can greatly improve the stability of the vibration damping device; the metal cross-spring has the characteristics of low axial stiffness and high radial stiffness, which can prevent the radial offset of the central axis while ensuring the output of the axial negative stiffness of the central axis.

[0018] (4) The mechanical wedge-lever type piezoelectric friction component in the present invention controls the piezoelectric ceramic actuator to generate a micro-displacement through an externally applied electric field. The micro-displacement drives the friction surfaces on both sides of the other end to clamp the high-stiffness friction parts inward through the amplification of the mechanical lever type stroke amplification mechanism, thereby providing friction damping for the system, and its magnitude can be actively adjusted by changing the driving voltage of the piezoelectric ceramic actuator. The mechanical wedge-lever type piezoelectric friction component in the present invention changes the clamping method, from the traditional elongation type to the clamping type, and uses the mechanical lever type stroke amplification mechanism to amplify the micro-displacement of the piezoelectric ceramic actuator, making up for the disadvantage of the insufficient stroke of the piezoelectric ceramic actuator.

[0019] (5) The mechanical lever type stroke amplification mechanism uses a flexible hinge as the connection point and the fulcrum. The flexible hinge has no stroke clearance and friction wear, and has many advantages such as compact structure, the friction force is not easily affected by the elastic deformation of parts, the micro-displacement can be efficiently transmitted, and the scaling ratio of mechanical displacement / clamping torque can be conveniently adjusted by using the lever arm size.

[0020] (6) In the mechanical wedge lever type piezoelectric friction assembly, the piezoelectric ceramic actuator and the mechanical lever type stroke amplification mechanism transfer micro-displacements through a wedge block. It is convenient to adjust the pre-tightening spring between the pre-tightening spring baffle and the wedge block to control the pre-tightening forces between the wedge block and the mechanical lever type stroke amplification mechanism, as well as between the mechanical lever type stroke amplification mechanism and the high-rigidity friction member, ensuring the transfer of the micro-displacements of the piezoelectric ceramic actuator. Moreover, the wedge structure can effectively avoid the clamping looseness caused by wear.

[0021] (7) Each damping element of the damping device provided by the present invention adopts an arrangement mode of a multi-parameter model. The adjustable damping and adjustable stiffness are connected in series through a central axis and then connected in parallel with a metal helical spring to jointly form the vibration transfer path of the damping device and support the load platform. Among them, the adjustable damping is provided by the mechanical wedge lever type piezoelectric friction assembly, and the adjustable stiffness is provided by the parallel connection of a new type of Maxwell magneto-resistive stress negative stiffness spring and a metal cross spring. The principle model of the damping device of the present invention is equivalent to the principle model of the traditional two-parameter damping device. The equivalent damping of the damping device of the present invention has the characteristic of changing with frequency, that is, the damping device of the present invention also realizes the effect of frequency-variable damping from the system structure level, which can further increase the adjustable range of the damping of the damping device and improve the damping performance.

[0022] (8) The damping device provided by the present invention realizes the adjustability of stiffness and damping. In practical applications, the damping device can actively adjust the stiffness parameter and damping parameter of the damping device according to the real-time working conditions, and achieve the best damping effect by reasonably selecting the values of the stiffness and damping parameters.

[0023] (9) Each damping component of the damping device provided by the present invention adopts a coaxial and compact installation method. Based on the central axis, the overall installation space is small and the circumferential symmetry is good, which is easy to be integrated into the damping path to achieve high-performance damping. Description of the Drawings

[0024] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required for use in the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained based on these drawings.

[0025] Figure 1 It is a half-sectional view of a new type of combined damping device with adjustable stiffness and damping;

[0026] Figure 2 It is a three-dimensional structure diagram of a metal cross spring;

[0027] Figure 3 It is a three-dimensional structure diagram of a magnetic stress negative stiffness spring;

[0028] Figure 4 is the schematic diagram of the magnetic stress negative stiffness spring;

[0029] Figure 5 is the three-dimensional structure diagram of the mechanical wedge lever type piezoelectric friction assembly;

[0030] Figure 6 is the schematic diagram of the mechanical wedge lever type piezoelectric friction assembly;

[0031] Figure 7 is the schematic diagram of the equivalent model of the vibration damping device of the present invention;

[0032] Figure 8 is the comparison diagram of the vibration damping effect curves of the traditional vibration damping device and the vibration damping device provided by the present invention.

[0033] Explanation of reference numerals in the drawings: 1. Load platform; 2. Bearing seat; 3. Linear bearing; 4. Metal helical spring; 5. Spring base; 6. Upper shell; 7. Lower shell; 8. Guide plate; 9. Lower stator; 10. Clamp; 11. Permanent magnet; 12. Rotor; 13. Upper stator; 14. Metal cross leaf spring; 15. Tightening nut; 16. Central shaft; 17. Mechanical wedge lever type piezoelectric friction assembly; 17-1. Pre-tightening bolt; 17-2. Pre-tightening spring baffle; 17-3. Pre-tightening spring; 17-4. Piezoelectric ceramic actuator; 17-5. Wedge block; 17-6. Flexible hinge; 17-7. Mechanical lever type stroke amplification mechanism; 17-8. High stiffness friction part. Detailed implementation manners

[0034] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

[0035] The purpose of the present invention is to provide a new type of combined vibration damping device with adjustable stiffness and damping to solve the problems existing in the above-mentioned prior art. It has non-linear frequency-varying characteristics of high static stiffness - low dynamic stiffness, large low-frequency damping - small high-frequency damping, and can well solve the contradiction between the bearing capacity and the vibration damping frequency band, as well as the contradiction between high-frequency and low-frequency vibration attenuation, and achieve high-performance vibration damping.

[0036] To make the above objects, features, and advantages of the present invention more obvious and understandable, the present invention will be further described in detail below in conjunction with the accompanying drawings and specific implementation manners.

[0037] As Figure 1 、 7As shown, a new type of combined vibration damping device with adjustable stiffness and damping provided by the present invention is composed of two components of adjustable stiffness and adjustable damping combined according to the layout mode of a multi-parameter system model. Among them, the adjustable stiffness part is realized by the parallel connection of a new type of Maxwell magnetoresistive stress negative stiffness spring and a metal cross spring 14 to achieve adjustable quasi-zero stiffness. The new type of Maxwell magnetoresistive stress negative stiffness spring includes an upper stator 13, a lower stator 9, a holder 10, a permanent magnet 11 and a mover 12; the adjustable damping part is realized by the multi-parameter model of the system and a mechanical wedge lever type piezoelectric friction component 17 to achieve adjustable frequency-variable damping; the remaining components include a load platform 1, a bearing seat 2, a linear bearing 3, a metal helical spring 4, a spring base 5, an upper shell 6, a lower shell 7, a guide plate 8, a fastening nut 15 and a central shaft 16 that connects the two parts of adjustable series stiffness and adjustable damping.

[0038] As Figure 1 , 2 shown, the load platform 1 is connected to the bearing seat 2 by bolts; the lower end of the metal helical spring 4 is sleeved on the spring base 5 for positioning, and the upper end supports the bearing seat 2 and the load platform 1; the outer end of the metal cross spring 14 is installed on the upper shell 6 by bolts, and the inner end is fixed on the shoulder of the central shaft 16 by the fastening nut 15. The characteristics of the high radial stiffness and low axial stiffness of the metal cross spring 14 can not only prevent the radial offset of the central shaft 16, but also do not affect the output of the axial negative stiffness; the guide plate 8 is installed on the lower shell 7 by bolts, guides the axial movement of the central shaft 16 and prevents the radial offset of the central shaft 16; the linear bearing 3 is installed on the bearing seat 2, and also guides and positions the axial movement of the central shaft 16; the spring base 5 is connected to the upper shell 6 by bolts; the upper shell 6 and the lower shell 7 are connected by bolts and compress and fix the internal new type of Maxwell magnetoresistive stress negative stiffness spring; the entire vibration damping device is coaxially arranged around the central shaft 16, with a compact structure and good circumferential symmetry.

[0039] As Figure 1 , 3As shown in the figure, the novel Maxwell magnetoresistive stress negative stiffness spring in the vibration damping device provided by the present invention includes an upper stator 13, a lower stator 9, a holder 10, a permanent magnet 11 and a mover 12. Among them, all the permanent magnets 11 have the same specifications and are evenly distributed and fixed in the corresponding slots of the annular holder 10, and the polarities of all the permanent magnets 11 are the same in the radial direction; the upper and lower parts of the holder 10 are limited and fixed by the upper stator 13 and the lower stator 9 respectively; the mover 12 is located inside the cavity formed by the upper stator 13, the lower stator 9 and the holder 10, and is coaxially arranged. Axially, there is a certain gap between the mover 12 and the upper stator 13 and the lower stator 9, and radially, there is a certain gap between the mover 12 and the permanent magnet 11; the entire novel Maxwell magnetoresistive stress negative stiffness spring is located inside the cavity formed by the upper shell 6 and the lower shell 7, wherein the mover 12 is fixed on the central shaft 16 by threads to output negative stiffness for the system. The novel Maxwell magnetoresistive stress negative stiffness spring uses the change of magnetoresistance in the magnetic circuit to generate Maxwell normal magnetic stress to achieve the purpose of generating negative stiffness. The magnitude of the Maxwell normal magnetic stress is related to key factors such as the initial gap, magnetic field strength and magnetic circuit permeability. Therefore, the present invention can conveniently and controllably adjust the magnitude of the negative stiffness in the device by changing the initial gap between the mover and the permanent magnet and the upper and lower stators, or replacing the permanent magnet with an electromagnetic coil and connecting a controllable current to the electromagnetic coil and other means.

[0040] As Figure 1 , 5As shown in the figure, the piezoelectric friction assembly in the vibration damping device provided by the present invention is a mechanical wedge lever type piezoelectric friction assembly 17, which includes a pre-tightening bolt 17-1, a pre-tightening spring baffle 17-2, a pre-tightening spring 17-3, a piezoelectric ceramic actuator 17-4, a wedge block 17-5, a mechanical lever type stroke amplification mechanism 17-7, and a high-rigidity friction member 17-8. The components in the mechanical wedge lever type piezoelectric friction assembly 17 are arranged in a left-right symmetric form as a whole; the displacement output end of the piezoelectric ceramic actuator 17-4 is fixedly connected to the wedge block 17-5 through a special solid glue; the wedge block 17-5 is in contact and cooperation with the wedge surface on the mechanical lever type stroke amplification mechanism 17-7 through the wedge surface to transmit micro-displacements; the mechanical lever type stroke amplification mechanism 17-7 can be divided into 4 pieces, which are connected by three flexible hinges 17-6. The flexible hinge is a flexible hinge, and both sides are fixed to the load platform 1 through bolts. The middle two pieces act as levers to amplify the micro-displacements output by the piezoelectric ceramic actuator 17-4, and then clamp the high-rigidity friction block 17-8 at the other end; the pre-tightening spring 17-3 is located between the pre-tightening spring baffle 17-2 and the wedge block 17-5; the pre-tightening spring baffle 17-2 is connected to both sides of the mechanical lever type stroke amplification mechanism 17-7 through the pre-tightening bolt 17-1, and squeezes the pre-tightening spring 17-3, playing a role in pre-tightening the cooperation between the mechanical lever type stroke amplification mechanism 17-7 and the wedge block 17-5 and the high-rigidity friction member 17-8; the high-rigidity friction member 17-8 is connected to the upper end of the central shaft 16 through a threaded hole. When the system vibrates, the friction force is generated by the relative movement between the high-rigidity friction member 17-8 and the mechanical lever type stroke amplification mechanism 17-7, thereby consuming the vibration energy of the system and providing friction damping for the system; by controlling the magnitude of the driving voltage of the piezoelectric ceramic actuator 17-4, the active adjustment of the friction damping can be realized.

[0041] The vibration damping principle of the vibration damping device in the present invention is described as follows:

[0042] The magnetic negative stiffness vibration damping device usually configures the magnets in an attracting or repelling form to achieve the negative stiffness characteristic and effectively attenuate low-frequency vibrations. However, the negative stiffness provided by the magnetic negative stiffness mechanism based on the attraction or repulsion force between magnets is relatively low. For a structure with a high static support stiffness, to provide sufficient magnetic negative stiffness to offset the positive stiffness of the structure, it is necessary to increase the volume or mass of the magnetic negative stiffness mechanism to achieve a higher negative stiffness, resulting in a larger volume and greater implementation difficulty of the vibration damping device. Therefore, the vibration damping device in the present invention adopts a new type of Maxwell magnetic resistance stress negative stiffness spring, which has the advantages of high magnetic negative stiffness, small volume, and light weight. Compared with the attraction or repulsion force between magnetic poles, the magnetic negative stiffness spring based on the Maxwell magnetic resistance stress principle has a higher force density, a compact structure, and a fast frequency response because the air-gap magnetic resistance changes with the displacement of the mover.

[0043] The Maxwell magnetoresistive stress is the magnetic normal force, and the direction of the force is along the normal direction of the air gap. The magnitude of the force can be expressed as follows:

[0044]

[0045] where S is the pole area of the air gap, μ 0 is the permeability of free space, B is the magnetic flux density in the air gap, which increases as the length of the air gap decreases.

[0046] As Figure 4 shown, the dashed boxes in the figure are magnetic field lines. The total magnetic flux flowing from the permanent magnet 11 to the mover 12 forms two magnetic flux loops in the upper stator 13 and the lower stator 9 respectively. Ignoring the influence of magnetic leakage, according to Gauss's law and Ampere's circuital law, the magnetic flux density in the air gap on the upper and lower surfaces of the mover 12 can be calculated as follows:

[0047]

[0048] where B 1 is the magnetic flux density in the air gap on the upper surface of the mover, B 2 is the magnetic flux density in the air gap on the lower surface of the mover, S 0 is the pole area of the mover at the air gap, B pm is the magnetic flux density of the magnet, S pm is the equivalent pole area of the magnet, x is the displacement of the mover from the equilibrium position in the axial direction, x 0 is the initial thickness of the air gap, l s is the length of the stator along the magnetic circuit direction, μ sr is the relative permeability inside the stator, l m is the length of the mover along the magnetic circuit direction, μ mr is the relative permeability inside the mover, l g is the length of the clamp along the magnetic circuit direction, μ gr is the relative permeability inside the clamp.

[0049] By combining equations (1) and (2), considering that the magnetic flux densities B 1 and B 2 are perpendicular to the upper and lower surfaces of the mover 12 and uniformly distributed, the expressions for the magnetic force and negative stiffness of the new Maxwell magnetoresistive stress negative stiffness spring can be derived as follows:

[0050]

[0051] As Figure 6As shown in the figure, the friction damping of the mechanical wedge lever type piezoelectric friction assembly 17 in the vibration damping device of the present invention can be adjusted by changing the driving voltage of the piezoelectric ceramic actuator 17-4. The piezoelectric ceramic actuator has the advantages of small volume, fast response speed, large output force, no heat generation, etc. According to the characteristics of the piezoelectric ceramic, the relationship between the axial output force and the driving voltage can be obtained as follows:

[0052] N = γ×k A ×n×d 33 ×U(4)

[0053] In the formula, γ is the reciprocal of the stroke magnification factor of the mechanical lever type stroke magnification mechanism, k A is the piezoelectric ceramic stiffness, n is the number of piezoelectric ceramic stacks, d 33 is the axial piezoelectric strain constant, U is the driving voltage, and N is the axial output force.

[0054] The friction damping has the characteristic of non-linearity. The dry friction non-viscous damping can be equivalent to viscous damping by using the equivalent linearization method (equivalent principle: the equivalent viscous damping and the non-viscous damping consume equal energy in one vibration cycle). According to the harmonic balance method, when the relative motion between the friction surfaces is a simple harmonic vibration, the energy consumed by the sliding friction force in one vibration cycle is 4μ d NX, and the energy consumed by the equivalent damping force is πCωX 2 . Therefore, the equivalent viscous damping coefficient between the friction surfaces is:

[0055]

[0056] In the formula, u d is the sliding friction coefficient between the friction contact surfaces, X is the amplitude of the simple harmonic vibration displacement, ω is the circular frequency of the simple harmonic vibration, and C is the equivalent viscous damping coefficient of the friction damping.

[0057] According to formulas (4) and (5), it can be known that the equivalent damping of the mechanical wedge lever type piezoelectric friction assembly 17 is linearly related to the driving voltage of the piezoelectric ceramic actuator 17-4.

[0058] As Figure 7 shown in the figure, the vibration damping device of the present invention has two vibration transmission paths, which can be respectively called the primary path and the secondary path; at the same time, the vibration damping elements in the vibration damping device of the present invention adopt the arrangement mode of the three-parameter model. The primary path is composed of the metal helical spring 4, which provides the main support stiffness K for the system; the secondary path is composed of the adjustable damping C and the adjustable stiffness K 1 connected in series, which plays the role of actively adjusting the stiffness and damping of the system, where the adjustable damping C is provided by the mechanical wedge lever type piezoelectric friction assembly 17, and the adjustable stiffness K 1 is provided by the parallel connection of the new type Maxwell magnetoresistive stress negative stiffness spring and the metal cross spring 14.

[0059] The vibration transfer rate function G of the vibration damping device of the present invention can be derived as follows:

[0060]

[0061] where x 0 is the vibration displacement of the load platform, x 1 is the vibration displacement of the base platform, and s is the Laplace operator.

[0062]

[0063] Comparing Equation (6) with the vibration transfer rate function Equation (7) of the above traditional passive vibration damping device, it can be obtained that:

[0064]

[0065] It can be seen from Equation (8) that the equivalent damping of the vibration damping device of the present invention has the characteristic of changing with frequency, that is, the vibration damping device realizes the effect of frequency-variable damping from the system structure level, and can further improve the vibration damping performance of the device.

[0066] Figure 8 is the vibration transfer rate curve diagram of a new type of combined vibration damping device with adjustable stiffness and damping provided by the present invention under the conditions of stiffness adjustment, damping adjustment and comprehensive adjustment. From Figure 8 it can be seen from the solid curve in that the vibration transfer rate of the traditional passive vibration damping device has a relatively high peak at the resonance peak, and the natural frequency is relatively high. From Figure 8 it can be seen from the dash-dotted curve in that after the damping of the system is adjusted by the vibration damping device of the present invention, the absolute damping increases, and the resonance peak of the vibration transfer rate is suppressed, and at the same time, the high-frequency attenuation rate can be maintained. From Figure 8 it can be seen from the dotted curve in that after the stiffness of the system is adjusted by the vibration damping device of the present invention, the dynamic stiffness of the system decreases, the natural frequency of the vibration transfer rate decreases, and the vibration isolation bandwidth increases. From Figure 8 it can be seen from the dot curve in that after the comprehensive adjustment of the vibration damping device of the present invention, the absolute damping of the system increases, the dynamic stiffness decreases, and at the same time, the effects of resonance peak suppression and vibration damping bandwidth increase are achieved, greatly improving the vibration damping performance of the device.

[0067] In the description of the present invention, it should be noted that the orientation or positional relationship indicated by the terms "center", "top", "bottom", "left", "right", "vertical", "horizontal", "inner", "outer", etc. is based on the orientation or positional relationship shown in the drawings, and is only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation of the present invention. In addition, the terms "first" and "second" are only used for descriptive purposes and cannot be understood as indicating or implying relative importance.

[0068] In the present invention, specific examples are used to illustrate the principle and implementation manner of the present invention. The description of the above embodiments is only used to help understand the method and its core idea of the present invention; at the same time, for those of ordinary skill in the art, according to the idea of the present invention, there will be changes in the specific implementation manner and application scope. In summary, the content of this specification should not be construed as a limitation on the present invention.

Claims

1. A novel combined vibration damping device with adjustable stiffness and damping, characterized in that: it includes a magneto-resistive stress negative stiffness spring located inside the housing and a piezoelectric friction assembly located inside the bearing seat; a central shaft is connected between the magneto-resistive stress negative stiffness spring and the piezoelectric friction assembly, a metal helical spring is sleeved outside the central shaft, the bottom of the metal helical spring is fixedly connected to a spring base located at the top of the housing, and the top of the metal helical spring is connected to the bottom of the bearing seat; the central shaft is fixedly connected to the top inside the housing through a metal cross-spring, the magneto-resistive stress negative stiffness spring and the metal cross-spring can be connected in parallel to achieve the adjustment of quasi-zero stiffness, and the piezoelectric friction assembly can achieve the adjustment of damping; a load platform is fixedly arranged at the top of the bearing seat; the housing includes an upper housing and a lower housing fixedly connected, the outer end of the metal cross-spring is installed on the upper housing through bolts, and the inner end of the metal cross-spring is fixed on the shoulder of the central shaft through a fastening nut; the spring base is fixedly connected to the top of the upper housing; the piezoelectric friction assembly includes a mechanical lever type stroke amplification mechanism, the mechanical lever type stroke amplification mechanism includes a symmetrically arranged first part and a second part, and a third part and a fourth part are symmetrically arranged between the first part and the second part; the first part and the second part are connected by a flexible hinge, the extension part between the second part and the third part is connected by a flexible hinge, and the third part and the fourth part are connected by a flexible hinge; the tops of the first part and the second part are fixedly connected to the load platform through bolts; a pre-tightening spring baffle is connected above the first part and the second part through a pre-tightening bolt, two pre-tightening springs are respectively connected to the bottom of the pre-tightening spring baffle with two wedge blocks, a piezoelectric ceramic actuator is arranged between the two wedge blocks, and the displacement output end of the piezoelectric ceramic actuator is fixedly connected to the wedge block through solid glue; wedge surfaces are arranged on the inner sides of the third part and the fourth part above the extension part, and the wedge block is in contact and cooperation with the wedge surface of the third part or the fourth part through the wedge surface at the end away from the piezoelectric ceramic actuator; a high-stiffness friction member is arranged between the third part and the fourth part, the high-stiffness friction member is located below the extension part, and the bottom of the high-stiffness friction member is connected to the upper end of the central shaft through a threaded hole; the frictional force generated by the relative movement between the high-stiffness friction member and the friction surface of the mechanical lever type stroke amplification mechanism can consume the vibration energy generated by the system vibration and provide frictional damping for the system; By controlling the magnitude of the driving voltage of the piezoelectric ceramic actuator, the active adjustment of the frictional damping can be achieved.

2. The novel combined vibration damping device with adjustable stiffness and damping according to claim 1, characterized in that: The magnetoresistive stress negative stiffness spring includes an upper stator, a holder, and a lower stator that are coaxially arranged from top to bottom in sequence; a plurality of mounting grooves are evenly arranged inside the holder, and permanent magnets are arranged in the mounting grooves, and the polarities of all the permanent magnets are the same in the radial direction; a mover is coaxially arranged inside the cavity formed by the upper stator, the lower stator, and the holder, and the mover has gaps with the upper stator and the lower stator in the axial direction, and has a gap with the permanent magnet in the radial direction; the mover is fixed to the central shaft by a thread; after the mover deviates from the equilibrium position due to vibration, the air gaps between the mover and the upper stator and the lower stator are different, resulting in different magnetoresistances in the upper and lower magnetic circuits, and different normal magnetic stresses are generated on the upper and lower surfaces of the mover, and the direction of the magnetic force is the same as the direction of the displacement deviation, so that the negative stiffness in the device can be adjusted by changing the initial gaps between the mover and the permanent magnet, the upper stator, and the lower stator.

3. The novel combined vibration damping device with adjustable stiffness and damping according to claim 1, characterized in that: a linear bearing is arranged at the bottom of the bearing seat, and the upper part of the central shaft passes through the linear bearing and then is connected to the piezoelectric friction assembly.

4. The novel combined vibration damping device with adjustable stiffness and damping according to claim 1, characterized in that: a guide plate is fixedly installed in the lower shell by bolts, and the bottom of the central shaft passes through the guide plate.

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