CN114135631B - Quasi-zero stiffness vibration isolator capable of adjusting negative stiffness in non-contact manner - Google Patents
Quasi-zero stiffness vibration isolator capable of adjusting negative stiffness in non-contact manner Download PDFInfo
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- CN114135631B CN114135631B CN202111505435.8A CN202111505435A CN114135631B CN 114135631 B CN114135631 B CN 114135631B CN 202111505435 A CN202111505435 A CN 202111505435A CN 114135631 B CN114135631 B CN 114135631B
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
- F16F—SPRINGS; SHOCK-ABSORBERS; MEANS FOR DAMPING VIBRATION
- F16F15/00—Suppression of vibrations in systems; Means or arrangements for avoiding or reducing out-of-balance forces, e.g. due to motion
- F16F15/02—Suppression of vibrations of non-rotating, e.g. reciprocating systems; Suppression of vibrations of rotating systems by use of members not moving with the rotating systems
- F16F15/03—Suppression of vibrations of non-rotating, e.g. reciprocating systems; Suppression of vibrations of rotating systems by use of members not moving with the rotating systems using magnetic or electromagnetic means
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
- F16F—SPRINGS; SHOCK-ABSORBERS; MEANS FOR DAMPING VIBRATION
- F16F15/00—Suppression of vibrations in systems; Means or arrangements for avoiding or reducing out-of-balance forces, e.g. due to motion
- F16F15/02—Suppression of vibrations of non-rotating, e.g. reciprocating systems; Suppression of vibrations of rotating systems by use of members not moving with the rotating systems
- F16F15/04—Suppression of vibrations of non-rotating, e.g. reciprocating systems; Suppression of vibrations of rotating systems by use of members not moving with the rotating systems using elastic means
- F16F15/046—Suppression of vibrations of non-rotating, e.g. reciprocating systems; Suppression of vibrations of rotating systems by use of members not moving with the rotating systems using elastic means using combinations of springs of different kinds
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
- F16F—SPRINGS; SHOCK-ABSORBERS; MEANS FOR DAMPING VIBRATION
- F16F15/00—Suppression of vibrations in systems; Means or arrangements for avoiding or reducing out-of-balance forces, e.g. due to motion
- F16F15/02—Suppression of vibrations of non-rotating, e.g. reciprocating systems; Suppression of vibrations of rotating systems by use of members not moving with the rotating systems
- F16F15/04—Suppression of vibrations of non-rotating, e.g. reciprocating systems; Suppression of vibrations of rotating systems by use of members not moving with the rotating systems using elastic means
- F16F15/06—Suppression of vibrations of non-rotating, e.g. reciprocating systems; Suppression of vibrations of rotating systems by use of members not moving with the rotating systems using elastic means with metal springs
- F16F15/067—Suppression of vibrations of non-rotating, e.g. reciprocating systems; Suppression of vibrations of rotating systems by use of members not moving with the rotating systems using elastic means with metal springs using only wound springs
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
- F16F—SPRINGS; SHOCK-ABSORBERS; MEANS FOR DAMPING VIBRATION
- F16F2222/00—Special physical effects, e.g. nature of damping effects
- F16F2222/06—Magnetic or electromagnetic
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
- F16F—SPRINGS; SHOCK-ABSORBERS; MEANS FOR DAMPING VIBRATION
- F16F2228/00—Functional characteristics, e.g. variability, frequency-dependence
- F16F2228/06—Stiffness
- F16F2228/063—Negative stiffness
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
- F16F—SPRINGS; SHOCK-ABSORBERS; MEANS FOR DAMPING VIBRATION
- F16F2230/00—Purpose; Design features
- F16F2230/18—Control arrangements
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
- F16F—SPRINGS; SHOCK-ABSORBERS; MEANS FOR DAMPING VIBRATION
- F16F2238/00—Type of springs or dampers
- F16F2238/02—Springs
- F16F2238/026—Springs wound- or coil-like
Abstract
The invention discloses a quasi-zero stiffness vibration isolator capable of realizing non-contact adjustment of negative stiffness, which comprises a vibration isolation box body, and an anti-overturning device, a negative stiffness electromagnetic adjusting device and a positive stiffness spring adjusting device which are arranged in the vibration isolation box body; the vibration isolation box body comprises a lower supporting platform, an upper supporting platform and four side plates which are enclosed between the upper supporting platform and the lower supporting platform; the anti-overturning device comprises four anti-overturning mechanisms which are sequentially arranged end to end, the four anti-overturning mechanisms are symmetrically arranged along a diagonal line, and the middle part of the anti-overturning mechanism surrounds a central area; the negative stiffness electromagnetic adjusting device comprises two oppositely arranged negative stiffness generating modules, and the negative stiffness generating modules face to the central area; the positive rate spring adjustment device is mounted in the central region. The beneficial effects of the invention are as follows: the invention has the characteristics of low natural frequency and high static bearing capacity, and can lead the resonance frequency to be very low on the premise of ensuring the bearing capacity, thereby widening the vibration isolation frequency band and improving the vibration isolation effect; and positive rigidity and negative rigidity can be adjusted according to actual demand.
Description
Technical Field
The invention relates to the technical field of vibration isolation, in particular to a quasi-zero stiffness vibration isolator capable of adjusting negative stiffness in a non-contact mode.
Background
The passive vibration isolator is a load-bearing energy-consuming element, has the advantages of simple structure, low energy consumption, easy realization, good economy and the like, and is a main means for isolating the transmission of the ship power mechanical vibration to the ship body. However, most of the passive vibration isolators designed based on classical vibration isolation theory at present have frequency retention of input and output, and cannot change the frequency spectrum structure of ship radiation noise; and the frequency of the external excitation of the linear vibration isolation system is smaller thanThe isolation capability of the low-frequency line spectrum of the natural frequency of the system is limited; at the same time, the high bearing capacity, ultra-low frequency vibration isolation, ultra-low rigidity, position stability, low resonance point transmissibility and wide frequency domain high attenuation rateThe contradiction has always limited the engineering applications of passive vibration isolators.
The quasi-zero stiffness vibration isolator with the parallel connection of the positive stiffness element and the negative stiffness element has the bearing capacity dependent on the positive stiffness element, and the negative stiffness element can reduce the dynamic stiffness of the system, can obtain the characteristics of high static stiffness for supporting the isolated equipment and low dynamic stiffness for reducing the vibration transmissibility, can ensure the low-frequency vibration isolation performance near the working point, can improve the stability of the system, and has wide application prospect. However, the installation space on the ship is limited, the engineering vibration isolator must be designed compactly, and the existing negative stiffness mechanism is often an oblique spiral spring, an oblique connecting rod or a buckling beam, so that the occupied space is large. In addition, the quasi-zero stiffness vibration isolator is a combined vibration isolator having a small combined stiffness in a certain section of the static equilibrium position. If the weight of the vibration-isolated object is not the designed ideal weight, that is, the vibration-isolated object is placed on the quasi-zero stiffness vibration isolator and cannot be stabilized at the ideal static balance position, the performance of the quasi-zero stiffness vibration isolator is seriously affected.
Disclosure of Invention
Aiming at the defects of the prior art, the invention provides the quasi-zero stiffness vibration isolator which is small in nonlinearity degree and easy to adjust and can adjust negative stiffness in a contactless manner.
The invention adopts the technical scheme that: a quasi-zero stiffness vibration isolator capable of adjusting negative stiffness in a non-contact manner comprises a vibration isolation box body, and an anti-overturning device, a negative stiffness electromagnetic adjusting device and a positive stiffness spring adjusting device which are arranged in the vibration isolation box body; the vibration isolation box body comprises a lower supporting platform, an upper supporting platform and four side plates which are enclosed between the upper supporting platform and the lower supporting platform; the anti-overturning device comprises four anti-overturning mechanisms which are sequentially arranged end to end, and the top and the bottom of each anti-overturning mechanism are respectively connected and fixed with the upper and lower support platforms; the four anti-overturning mechanisms are symmetrically arranged along the diagonal, and the middle parts are enclosed to form a central area; the negative stiffness electromagnetic adjusting device comprises two oppositely arranged negative stiffness generating modules, and the negative stiffness generating modules face to the central area; the positive stiffness spring adjusting device is arranged in the central area and comprises a worm and gear mechanism and a spiral spring, the worm and gear mechanism is arranged on the lower supporting platform, the input end of the worm and gear mechanism penetrates through the side plate to extend out of the vibration isolation box body, the output end of the worm and gear mechanism is connected with the spiral spring, the spiral spring is vertically arranged, and the worm and gear mechanism can drive the spiral spring to move along the vertical direction.
According to the scheme, each anti-overturning mechanism is provided with a supporting structure, and the supporting structure comprises a first fixed block, a second fixed block, a third fixed block, a fourth fixed block, a plurality of transverse reeds and a plurality of vertical reeds, wherein the first fixed block, the second fixed block, the third fixed block and the fourth fixed block are connected with the lower supporting platform; the second fixed block is arranged at the upper part of the first fixed block and is connected with the third fixed block through at least one transverse reed; the third fixed block is connected with the fourth fixed block through at least one vertical reed.
According to the scheme, each negative rigidity generation module comprises a C-shaped yoke and a permanent magnet, and the bottom and the top of the C-shaped yoke are respectively connected with the upper support platform and the lower support platform; the open sides of the C-shaped yokes of the two negative rigidity generating modules are opposite; an upper middle yoke and a lower middle yoke are arranged in an opening of the C-shaped yoke, and coils are wound outside the two middle yokes to form an electromagnet; the permanent magnet and the two electromagnets are vertically arranged in the opening of the C-shaped yoke in the homopolar direction, the permanent magnet is positioned between the two electromagnets, and the three magnets form a closed magnetic loop in the C-shaped yoke; the permanent magnet is connected with the upper supporting platform through a supporting plate.
According to the scheme, the supporting plates of the two negative stiffness generating modules are connected through the connecting plate, the connecting plate is provided with the height indicating needle, and the height indicating needle and the permanent magnet are positioned at the same height; one end of the height indicator needle extends out of the side plate.
According to the scheme, the supporting plate is an L-shaped supporting plate, the top of the vertical section of the supporting plate is connected with the upper supporting platform, and the horizontal section of the supporting plate is provided with the permanent magnet; the connecting plate is connected with the vertical section of the supporting plate.
According to the scheme, the negative rigidity generating module is further provided with limiting rubber, and the limiting rubber is arranged at the upper end and the lower end of the supporting structure of the anti-overturning mechanism.
According to the scheme, the coil is a water-cooled coil.
According to the scheme, the turbine worm mechanism comprises a plurality of supports, a worm and a turbine, wherein the supports are arranged on the lower supporting platform at intervals; the worm sequentially penetrates through the operation holes on the side plates extending out of the back of each support; the worm is matched with the turbine, the middle part of the turbine is in threaded fit with the vertical bolt, and the bottom of the vertical bolt is connected with the lower supporting platform; the spiral spring is coaxially matched with the turbine, the upper end of the spiral spring is contacted with the inner top of the upper supporting platform, the lower end of the spiral spring is fixed on the turbine, and when the worm is rotated, the turbine rotates along with the turbine and drives the spiral spring to lift along the axis direction of the vertical bolt.
According to the scheme, the positive stiffness spring adjusting device is further provided with two groups of limiting mechanisms symmetrically distributed on the outer side of the spiral spring, each limiting mechanism comprises a limiting rod and a limiting block, the limiting rods are vertically arranged, and the lower ends of the limiting rods are connected with the lower supporting platform; the limiting block is fixed on the limiting rod.
According to the scheme, the C-shaped yoke and the middle yoke are made of DT4C materials, and the permanent magnet is made of rare earth permanent magnet materials.
The beneficial effects of the invention are as follows:
(1) The quasi-zero stiffness vibration isolator has the characteristics of low natural frequency and high static bearing capacity, and can enable the resonance frequency to be very low on the premise of ensuring the bearing capacity, so that the vibration isolation frequency band is widened, and the vibration isolation effect is improved; and positive rigidity and negative rigidity can be adjusted according to actual demand.
(2) The electromagnetic regulating device with negative rigidity adopts three magnets to vertically and homopolar arrange, has no mechanical friction, does not need lubrication, has long service life, has small nonlinearity degree, and can be well matched with positive rigidity.
(3) The electromagnet in the negative stiffness electromagnetic adjusting device is wound with a coil, the magnitude of the negative stiffness can be controlled through current, and the negative stiffness electromagnetic adjusting device is easy to adjust and convenient to realize the self-adaptive control of the negative stiffness of the quasi-zero stiffness vibration isolator.
(4) Except for the electromagnet and the permanent magnet, other devices in the vibration isolator are made of non-magnetic or weak-magnetic metal materials, so that the interference to the magnetic field generated by the permanent magnet is avoided.
(5) The negative rigidity is controlled to be matched with the positive rigidity by controlling the position of the spring to be unchanged and adjusting the coil current of the electromagnet, so that the load with different weights can be adapted.
(6) The vibration isolator has the advantages of compact structure, large bearing capacity, simple and convenient control and the like, has good vibration isolation effect on equipment with large-amplitude excitation and different weights, and has wide vibration isolation frequency band and high amplitude attenuation rate.
Drawings
FIG. 1 is a schematic diagram of the overall structure of an embodiment of the present invention.
Fig. 2 is a top view of the present embodiment without the upper support platform.
Fig. 3 is a schematic diagram showing the connection of the anti-overturning device, the negative stiffness electromagnetic adjusting device and the positive stiffness spring adjusting device in the embodiment.
Fig. 4 is an assembly schematic diagram of the anti-overturning device in this embodiment.
Fig. 5 is an assembly schematic diagram of the negative stiffness electromagnetic adjusting device in the present embodiment.
Fig. 6 is an assembly schematic of the positive rate spring adjusting device in this embodiment.
Fig. 7 is a graph of static stiffness versus displacement calculation in this example.
Wherein: 1. a lower support platform; 2. a machine foot; 3. a bolt A; 4. a side plate; 5. an upper support platform; 6. a bolt B; 7. an operation hole; 8. a wire hole; 9. a display hole; 10. a negative stiffness electromagnetic adjusting device; 11. positive rate spring adjustment means; 12. an anti-overturning device; 13. a bolt C; 14. a bolt D; 15. a transverse reed; 16. a vertical reed; 17. a bolt E; 18. a support structure; 18.1, a first fixed block; 18.2, a second fixed block; 18.3, a third fixed block; 18.4, a fourth fixed block; 19. c-shaped yoke iron; 20. a permanent magnet; 21. a coil; 22. limit rubber; 23. a height indicator pin; 24. a vertical bolt; 25. a worm gear mechanism; 26. a worm; 27. a coil spring; 28. a support; 29. a limit rod; 30. a limiting block; 31. a support plate; 31.1, vertical section; 31.2, horizontal segment; 32. a connecting plate; 33. and a middle yoke.
Detailed Description
For a better understanding of the present invention, the present invention is further described below with reference to the drawings and specific examples.
The quasi-zero stiffness vibration isolator capable of adjusting negative stiffness in a non-contact manner as shown in fig. 1-3 comprises a vibration isolation box body, and an anti-overturning device 12, a negative stiffness electromagnetic adjusting device 10 and a positive stiffness spring adjusting device 11 which are arranged in the vibration isolation box body; the vibration isolation box body comprises a lower supporting platform 1, an upper supporting platform 5 and four side plates 4 which are enclosed between the upper supporting platform 1 and the lower supporting platform 1; the anti-overturning device 12 comprises four anti-overturning mechanisms which are sequentially arranged end to end, and the top and the bottom of each anti-overturning mechanism are respectively connected and fixed with the upper and lower support platforms 1; the four anti-overturning mechanisms are symmetrically arranged along the diagonal, and the middle parts are enclosed to form a central area; the negative stiffness electromagnetic adjusting device 10 comprises two oppositely arranged negative stiffness generating modules, wherein the negative stiffness generating modules face to the central area; the positive stiffness spring adjusting device 11 is arranged in the central area, the positive stiffness spring adjusting device 11 comprises a worm gear mechanism 25 and a spiral spring 27, the worm gear mechanism 25 is arranged on the lower supporting platform 1, the input end of the worm gear mechanism 25 penetrates through the side plate 4 to extend out of the vibration isolation box body, the output end of the worm gear mechanism 25 is connected with the spiral spring 27, the spiral spring 27 is vertically arranged, and the worm gear mechanism 25 can drive the spiral spring 27 to move along the vertical direction.
In the vibration isolation box body shown in fig. 1, the lower support platform 1 is connected with the side plate 4 through a plurality of bolts B6, and the bottom of the lower support platform 1 is connected with the organic leg 2 through a bolt A3; the upper supporting platform 5 is connected with the side plate 4 in an embedded mode. The side plate 4 is provided with an operation hole 7 for operating the worm 26, a wire hole 8 for connecting a power wire and a display hole 9 for displaying the balance position.
The anti-toppling device 12 provides torsional rigidity to the overall device, effectively preventing the isolator from producing a large torsional amplitude. In the anti-toppling device 12 shown in fig. 4, each anti-toppling mechanism is provided with a support structure 18, and the support structure 18 comprises a first fixed block 18.1 (which can be connected by bolts) connected with the lower support platform 1, a second fixed block 18.2, a third fixed block 18.3, a fourth fixed block 18.4 (which is connected by bolts D14) connected with the upper support platform 5, a plurality of transverse reeds 15 and a plurality of vertical reeds 16; the second fixed block 18.2 is arranged at the upper part of the first fixed block 18.1, and the second fixed block 18.2 is connected with the third fixed block 18.3 through at least one transverse reed 15; the third fixed block 18.3 is connected to the fourth fixed block 18.4 by at least one vertical reed 16.
In this embodiment, the second fixing block 18.2 is connected to the third fixing block 18.3 by two parallel transverse reeds 15, and the third fixing block 18.3 is connected to the fourth fixing block 18.4 by a vertical reed 16; each reed is connected with the corresponding fixed block through a bolt E17.
The negative stiffness electromagnetic adjusting device 10 adopts a mode of vertical homopolar arrangement of three magnets as a negative stiffness generating module, and is used for realizing the self-adaptive control of the negative stiffness of the quasi-zero stiffness vibration isolator. As shown in fig. 5, the negative stiffness electromagnetic adjusting apparatus 10 includes two negative stiffness generating modules arranged opposite to each other, each of the negative stiffness generating modules including a C-shaped yoke 19, a permanent magnet 20, and two intermediate yokes 33 wound with coils 21, the C-shaped yokes 19 being respectively connected (bolted) to the lower support platform 1; the opening sides of the C-shaped yokes 19 of the two negative rigidity generating modules are opposite to each other and are positioned below the transverse reed 16; an upper middle yoke 33 and a lower middle yoke 33 are arranged in the opening of the C-shaped yoke 19, and a coil 21 is wound outside the two middle yokes 33 to form an electromagnet; the permanent magnet 20 and the electromagnets are vertically arranged in the opening of the C-shaped yoke in the homopolar direction, the permanent magnet 20 is positioned between the two electromagnets, a closed magnetic loop is formed in the C-shaped yoke 19 by the permanent magnet 20 and the electromagnets, and repulsive force is generated between the permanent magnet 20 and the electromagnets; the permanent magnet 20 is connected to the upper support platform 5 by a support plate 31. In this embodiment, the coil 21 is wound around the middle portion of the middle yoke 33, and the upper end of the middle yoke 33 is connected to the upper support platform 5 by bolts.
In the invention, the supporting plate 31 is positioned in the central area, the permanent magnet 20 is connected with the upper supporting platform 5 through the supporting plate 31 and moves together with the upper supporting platform 5, and in the moving process, a magnetic field is induced by electromagnets at the upper end and the lower end and magnetic force similar to the displacement direction is generated, so that the negative rigidity is realized. The coil 21 is connected to an electric wire introduced from the wire hole 8, and the negative stiffness of the vibration isolator is controlled by varying the current input to the coil 21. In the closed magnetic circuit of the C-shaped yoke 19, no current is introduced into the coil 21 of the electromagnet, the middle yoke 33 can induce a magnetic field by the permanent magnet 20 to generate corresponding negative rigidity, and exciting current with the same direction as the original magnetic field can be input to the coil 21 to enhance the negative rigidity.
Preferably, the supporting plates 31 of the two negative stiffness generating modules are connected through a connecting plate 32, and the connecting plate 32 is provided with a height indicating needle 23, and the height indicating needle 23 and the permanent magnet 20 are positioned at the same height; one end of the height indicator pin 23 extends out of the side plate 4 from the display hole 9 and is used for displaying the real-time position of the permanent magnet 20, so that the balance point position of the quasi-zero stiffness vibration isolator can be conveniently adjusted.
In this embodiment, the support plate 31 is an L-shaped support plate, the top of the vertical section 31.1 of the support plate 31 is connected with the upper support platform 5 (can be connected by a bolt C13), and the permanent magnet 20 is mounted on the horizontal section of the support plate 31; the connection plate 32 is connected to the vertical section of the support plate 31.
Preferably, the negative stiffness generating module is further provided with a limit rubber 25, and the limit rubber 25 is disposed at the upper and lower ends of the support structure 18 of the anti-overturning mechanism (specifically, disposed at the upper and lower parts of the first fixing block 18.1), so as to prevent the permanent magnet 20 from colliding with the C-shaped yoke 19 during movement. In this embodiment, the connection plate 32, the support plate 31 and the height indicator pin 23 are reciprocally movable up and down with the permanent magnet 20, and the connection plate 32 moves between the upper and lower portions of the first fixed block 18.1.
Preferably, the coil 21 is a water-cooled coil 21, so as to effectively solve the problem of heat generation of the coil 21.
The positive stiffness spring adjusting device 11 is used for controlling the positive stiffness of the zero stiffness vibration isolator. As shown in fig. 6, the worm wheel and worm mechanism 25 comprises a plurality of support seats 28, a worm 26 and a worm wheel, wherein the support seats 28 are arranged on the lower support platform 1 at intervals (can be connected by bolts); the worm 26 sequentially passes through the operation holes on the rear extension side plates 4 of the supports 28; the worm 26 is matched with a turbine, the middle part of the turbine is in threaded fit with a vertical bolt 24, and the bottom of the vertical bolt 24 is connected with the lower support platform 1; the spiral spring 27 is coaxially matched with the turbine, the upper end of the spiral spring 27 is in contact with the inner top of the upper supporting platform 5, the lower end of the spiral spring 27 is fixed on the turbine, when the worm 26 is rotated, the turbine rotates along with the turbine, the spiral spring 27 is driven to lift along the axis direction of the vertical bolt 24, the positive stiffness value of the spiral spring 27 is changed, and therefore the balance point position of the quasi-zero stiffness vibration isolator is convenient to adjust. In this embodiment, there are 3 seats 28 for fixing the position of the worm 2626, so as to effectively control the vertical movement of the coil spring 27.
Preferably, the positive stiffness spring adjusting device 11 is further provided with two groups of limiting mechanisms symmetrically distributed on the outer side of the spiral spring 27, so as to limit the spiral spring 27 to shift left and right and enable the spiral spring 27 to move only in the vertical direction; the limiting mechanism comprises a limiting rod 29 and a limiting block 30, wherein the limiting rod 29 is vertically arranged, and the lower end of the limiting rod 29 is connected with the lower supporting platform 1; the limiting block 30 is fixed on the limiting rod 29.
In the invention, the C-shaped yoke 19 and the middle yoke 33 are both made of DT4C materials with low coercive force and high magnetic permeability, and the permanent magnet 20 is made of rare earth permanent magnet materials; other components and structures are made of non-magnetic or weak magnetic materials, such as 304 stainless steel.
The working principle of the negative stiffness electromagnetic adjusting device 10 is as follows: the middle permanent magnet 20 magnetizes the upper and lower middle yokes 33, thereby generating attractive force. The magnitude and direction of the magnetic field inside the intermediate yoke 33 are changed by changing the magnitude and direction of the current of the coil 21, thereby changing the magnitude of the electromagnetic negative stiffness. The force applied to the middle yoke 33 can be divided into the force applied to the permanent magnet 20 and the permanent magnet 33 itself (permanent magnetic force) and the force applied to the permanent magnet 20 (electromagnetic force) due to the current of the coil 21, wherein the permanent magnetic force is:
wherein F is pc Representing the permanent magnetic acting force, N; a, a 1 Representing constant coefficients, nm 4 ；q 1 Representing the displacement parameter (q 1 ＝z c +a 2 )，m；z c Representing the distance of the permanent magnet 20 from the intermediate yoke 33, mm, when the permanent magnet 20 is in the intermediate equilibrium position; a, a 2 Representing a displacement constant coefficient, m; z represents the amount of vertical displacement of the permanent magnet 20 from the equilibrium position, mm.
The electromagnetic acting force is as follows:
wherein F is pe Represents electromagnetic force, N; a, a 3 Representing the current parameter, A -1 The method comprises the steps of carrying out a first treatment on the surface of the sign represents a sign function; i represents the coil 21 current, a; b 3 Representing the current parameter, A -1 ；b 1 Representing constant coefficients, nm 4 ；q 2 Representing the displacement parameter (q 2 ＝z c +b 2 )，m；b 2 Represents the constant displacement coefficient, m.
The permanent magnet 20 and the electromagnet are magnetized in the same direction, and the structure is similar to a three-magnet negative stiffness structure. When no current is supplied to the coil 21, the magnetic flux density is small, and the magnetic flux density is mainly generated by the permanent magnet 20. As the magnitude of the current increases, so does the magnetic flux density. When no current is supplied to the coil 21, a three-magnet negative stiffness structure can be formed due to the magnetic field induced by the permanent magnet 20 in the electromagnet, and the negative stiffness phenomenon is more obvious along with the increase of the current.
The working principle of the invention is as follows: the invention provides negative rigidity by utilizing a three-magnet vertical homopolar arrangement structure, wherein the middle part of the three-magnet vertical homopolar arrangement structure is provided with a permanent magnet 20, the upper part and the lower part are provided with electromagnets, and a C-shaped yoke 19 is used for closing a magnetic loop; after the coil springs 27 are connected in parallel, the total stiffness of the system at the equilibrium position is small (static stiffness versus displacement calculation curve of the vibration isolator is shown in fig. 6). When the vibration isolator is used, an object to be isolated is fixed at the center position of the upper part of the upper supporting platform 5, and when the mass of the object to be isolated changes, the current of the coil 21 and the worm 26 are regulated to enable the negative rigidity to be matched with the positive rigidity, so that the vibration isolator can be in a balance position. Therefore, the dynamic stiffness of the whole device is very small, and the natural frequency during vibration is very low. When the whole device is in a static state, the permanent magnet 20 is positioned between the two middle yokes 33, and the axial force generated by the electromagnet on the permanent magnet 20 is zero due to symmetry, so that the static bearing capacity of the vibration isolator is not affected.
What is not described in detail in this specification is prior art known to those skilled in the art. The above embodiments are provided to illustrate the technical concept and features of the present invention and are intended to enable those skilled in the art to understand the content of the present invention and implement the same, and are not intended to limit the scope of the present invention. All equivalent changes or modifications made in accordance with the spirit of the present invention should be construed to be included in the scope of the present invention.
Claims (6)
1. The quasi-zero stiffness vibration isolator capable of adjusting negative stiffness in a non-contact manner is characterized by comprising a vibration isolation box body, and an anti-overturning device, a negative stiffness electromagnetic adjusting device and a positive stiffness spring adjusting device which are arranged in the vibration isolation box body; the vibration isolation box body comprises a lower supporting platform, an upper supporting platform and four side plates which are enclosed between the upper supporting platform and the lower supporting platform; the anti-overturning device comprises four anti-overturning mechanisms which are sequentially arranged end to end, and the top and the bottom of each anti-overturning mechanism are respectively connected and fixed with the upper and lower support platforms; the four anti-overturning mechanisms are symmetrically arranged along the diagonal, and the middle parts are enclosed to form a central area; the negative stiffness electromagnetic adjusting device comprises two oppositely arranged negative stiffness generating modules, and the negative stiffness generating modules face to the central area; the positive stiffness spring adjusting device is arranged in the central area and comprises a turbine worm mechanism and a spiral spring, the turbine worm mechanism is arranged on the lower supporting platform, the input end of the turbine worm mechanism penetrates through the side plate and extends out of the vibration isolation box body, the output end of the turbine worm mechanism is connected with the spiral spring, the spiral spring is vertically arranged, and the turbine worm mechanism can drive the spiral spring to move along the vertical direction; each anti-overturning mechanism is provided with a supporting structure, and the supporting structure comprises a first fixed block, a second fixed block, a third fixed block, a fourth fixed block, a plurality of transverse reeds and a plurality of vertical reeds, wherein the first fixed block, the second fixed block, the third fixed block and the fourth fixed block are connected with the lower supporting platform; the second fixed block is arranged at the upper part of the first fixed block and is connected with the third fixed block through at least one transverse reed; the third fixed block is connected with the fourth fixed block through at least one vertical reed; each negative rigidity generation module comprises a C-shaped yoke and a permanent magnet, wherein the bottom and the top of the C-shaped yoke are respectively connected with the upper and lower support platforms; the open sides of the C-shaped yokes of the two negative rigidity generating modules are opposite; an upper middle yoke and a lower middle yoke are arranged in an opening of the C-shaped yoke, and coils are wound outside the two middle yokes to form an electromagnet; the permanent magnet and the two electromagnets are vertically arranged in the opening of the C-shaped yoke in the homopolar direction, the permanent magnet is positioned between the two electromagnets, and the three magnets form a closed magnetic loop in the C-shaped yoke; the permanent magnet is connected with the upper supporting platform through a supporting plate; the support plates of the two negative stiffness generating modules are connected through a connecting plate, and a height indicating needle is arranged on the connecting plate and is positioned at the same height with the permanent magnet; one end of the height indicator needle extends out of the side plate; the turbine worm mechanism comprises a plurality of supports, a worm and a turbine, and the supports are arranged on the lower supporting platform at intervals; the worm sequentially penetrates through the operation holes on the side plates extending out of the back of each support; the worm is matched with the turbine, the middle part of the turbine is in threaded fit with the vertical bolt, and the bottom of the vertical bolt is connected with the lower supporting platform; the spiral spring is coaxially matched with the turbine, the upper end of the spiral spring is contacted with the inner top of the upper supporting platform, the lower end of the spiral spring is fixed on the turbine, and when the worm is rotated, the turbine rotates along with the turbine and drives the spiral spring to lift along the axis direction of the vertical bolt.
2. The quasi-zero stiffness vibration isolator according to claim 1, wherein the support plate is an L-shaped support plate, the top of the vertical section of the support plate is connected with the upper support platform, and a permanent magnet is mounted on the horizontal section of the support plate; the connecting plate is connected with the vertical section of the supporting plate.
3. The quasi-zero stiffness vibration isolator of claim 1 wherein the negative stiffness generating module is further provided with a spacing rubber disposed at upper and lower ends of the support structure of the anti-toppling mechanism.
4. The quasi-zero stiffness vibration isolator of claim 1 wherein the coil is a water cooled coil.
5. The quasi-zero stiffness vibration isolator according to claim 1, wherein the positive stiffness spring adjusting device is further provided with two groups of limiting mechanisms symmetrically distributed on the outer sides of the spiral springs, each limiting mechanism comprises a limiting rod and a limiting block, the limiting rods are vertically arranged, and the lower ends of the limiting rods are connected with the lower supporting platform; the limiting block is fixed on the limiting rod.
6. The quasi-zero stiffness vibration isolator of claim 1 wherein the C-yoke and the intermediate yoke are formed of DT4C material and the permanent magnets are formed of rare earth permanent magnet material.
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