CN113389843A - Rigidity-adjustable electromagnetic pneumatic quasi-zero rigidity vibration isolator - Google Patents

Rigidity-adjustable electromagnetic pneumatic quasi-zero rigidity vibration isolator Download PDF

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CN113389843A
CN113389843A CN202110803090.8A CN202110803090A CN113389843A CN 113389843 A CN113389843 A CN 113389843A CN 202110803090 A CN202110803090 A CN 202110803090A CN 113389843 A CN113389843 A CN 113389843A
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pneumatic
quasi
stiffness
electromagnetic
vibration isolator
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谢英江
孙景工
牛福
孟令帅
赵万卓
杨瑞锋
高妍
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Institute Of Logistics Science And Technology Institute Of Systems Engineering Academy Of Military Sciences
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Institute Of Logistics Science And Technology Institute Of Systems Engineering Academy Of Military Sciences
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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
    • F16F15/023—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 fluid means
    • F16F15/0232—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 fluid means with at least one gas spring
    • 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
    • F16F15/023—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 fluid means
    • F16F15/027—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 fluid means comprising control arrangements
    • F16F15/0275—Control of stiffness
    • 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
    • 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
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
    • F16F—SPRINGS; SHOCK-ABSORBERS; MEANS FOR DAMPING VIBRATION
    • F16F2222/00—Special physical effects, e.g. nature of damping effects
    • F16F2222/12—Fluid damping
    • F16F2222/126—Fluid damping using gases
    • 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
    • F16F2228/066—Variable stiffness
    • 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
    • F16F2230/0005—Attachment, e.g. to facilitate mounting onto confer adjustability
    • 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
    • F16F2230/0011—Balancing, e.g. counterbalancing to produce static balance
    • 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
    • F16F2230/06—Fluid filling or discharging
    • 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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  • Engineering & Computer Science (AREA)
  • General Engineering & Computer Science (AREA)
  • Physics & Mathematics (AREA)
  • Acoustics & Sound (AREA)
  • Aviation & Aerospace Engineering (AREA)
  • Mechanical Engineering (AREA)
  • Electromagnetism (AREA)
  • Vibration Prevention Devices (AREA)

Abstract

The invention discloses an electromagnetic pneumatic quasi-zero stiffness vibration isolator with adjustable stiffness, which comprises a base; the base is provided with 1 group of pneumatic springs and 2 groups of electromagnetic springs; the 2 groups of electromagnetic springs are respectively and fixedly connected with two sides of the stud bolt, the 2 groups of electromagnetic springs can drive the stud bolt to move up and down, and the connecting piece is matched with the stud bolt; the pneumatic spring is fixedly connected with the connecting piece and can drive the connecting piece to move up and down; the connecting piece is connected with the load platform; the load platform is used for placing a load. The invention utilizes the negative stiffness generated by the electromagnetic spring to balance the positive stiffness generated by the pneumatic spring, and realizes that the static balance position is in a quasi-zero stiffness state; when the load changes, the air pressure of the introduced air chamber and the current of the coil are changed, so that the working position and the quasi-zero rigidity characteristic of the system can be kept unchanged, and the excellent low-frequency vibration isolation performance is kept; the invention has wide application range, excellent low-frequency vibration isolation performance, compact structure, simple operation and easy control.

Description

Rigidity-adjustable electromagnetic pneumatic quasi-zero rigidity vibration isolator
Technical Field
The invention belongs to the technical field of vibration isolators, and particularly relates to an electromagnetic pneumatic quasi-zero stiffness vibration isolator with adjustable stiffness.
Background
According to vibration theory, the linear vibration isolator only has the excitation frequency larger than the natural frequency of the system
Figure BDA0003165448260000011
The vibration isolation effect can be exerted in times, and if low-frequency vibration isolation is realized, the system rigidity is reduced, so that the static deformation of the vibration isolation system is increased, and the stability of the system is reduced. The mechanism for providing negative stiffness and the positive stiffness mechanism are connected in parallel to form the quasi-zero stiffness vibration isolator, so that the quasi-zero stiffness vibration isolator has low dynamic stiffness and high static supporting capacity at a static balance position, the inherent frequency of a system is reduced, and the low-frequency vibration isolation performance is improved.
When the quasi-zero stiffness vibration isolator bears load, the quasi-zero stiffness vibration isolator has dynamic stiffness approaching zero in a small range near a static balance position. When the bearing quality changes, the vibration isolation system deviates from the original working state, and the vibration isolation effect is reduced or even lost. Therefore, a need exists for a vibration isolator that maintains a quasi-zero stiffness characteristic for different loads. CN210423559U proposes a zero stiffness vibration isolation device with adjustable negative stiffness, in which the positive and negative stiffness mechanisms are both composed of linear springs, and when the load changes, the height of the horizontal spring is manually adjusted to keep the precompression amount of the spring, and ensure the matching with the negative stiffness, but the structure is complex, the adjustment precision of the height and horizontal position is low, and the reliability is poor. CN206234312U proposes a magnetic quasi-zero stiffness vibration isolator with adjustable stiffness, in which an elastic bag body providing positive stiffness is connected in parallel with three transversely magnetized rectangular magnetic blocks providing negative stiffness, when the vibration isolation quality changes, the working position of the elastic bag body is kept unchanged by inflation and deflation, and the position of the magnet is transversely adjusted to match the positive stiffness at the moment, but the negative stiffness mechanism has a complex structure and low adjustment precision.
Disclosure of Invention
The invention provides an electromagnetic pneumatic quasi-zero stiffness vibration isolator with adjustable stiffness, which comprises: a base;
the base is provided with 1 group of pneumatic springs and 2 groups of electromagnetic springs, and the pneumatic springs are arranged among the 2 groups of electromagnetic springs;
the 2 groups of electromagnetic springs are respectively and fixedly connected with the two sides of the stud bolt, and the 2 groups of electromagnetic springs can drive the stud bolt to move up and down;
the upper end of the pneumatic spring is fixedly connected with the lower end of the connecting piece, and the pneumatic spring can drive the connecting piece to move up and down;
the connecting piece is provided with a through hole, and the stud bolt is inserted into the through hole to be matched with the connecting piece;
the upper end of the connecting piece is fixedly connected with the second end of the connecting rod, and the first end of the connecting rod is fixedly connected with the lower end of the load platform;
the load platform is used for placing a load.
Further, 2 electromagnetic springs are symmetrically arranged on two sides of the pneumatic spring along the axis of the pneumatic spring.
Further, base upper end both sides are provided with first recess and internal thread, and the centre is equipped with second recess and through-hole.
Furthermore, the electromagnetic spring comprises a sleeve, a first space, a second space and a third space are arranged in the sleeve from bottom to top, the first space is the same as the third space, and the diameter of the second space is smaller than that of the first space or that of the third space;
1 metal coil is respectively installed in the first space and the third space in a matched mode, an annular magnet is installed in the second space in a matched mode, and the annular magnet can slide up and down along the inner wall of the second space;
one side of the annular magnet is fixedly connected with one side of the stud;
the sleeve is arranged in the first groove in a matched mode;
the guide post passes through the 2 metal coils and the annular magnet;
the guide post is fixedly connected with the sleeve;
the lower end of the guide pillar is provided with an external thread which is connected with the internal thread of the base.
Further, the electromagnetic spring further comprises a compression nut;
the metal coil is fixed by a compression nut;
the guide post penetrates through the compression nut;
the compression nut is in threaded connection with the guide pillar.
Furthermore, an internal thread is arranged on one side of the annular magnet, and the annular magnet is in threaded connection with one side of the stud bolt through the internal thread.
Further, the sleeve side wall is provided with a sliding groove, and after the annular magnet is connected with the stud bolts, the stud bolts can move in the vertical direction.
Furthermore, the current of the 2 metal coils is direct current and the current direction is the same.
Further, the pneumatic spring comprises a pressure cylinder, and the pressure cylinder is installed in the second groove of the base;
the bottom of the pressure cylinder is provided with a threaded hole which is connected with the through hole of the base through a bolt;
the first end of the piston rod is arranged in the pressure cylinder, and the first end of the piston rod divides the pressure cylinder into an upper air chamber and a lower air chamber;
the upper air chamber is provided with an upper air hole, and the lower air chamber is provided with a lower air hole;
the second end of the piston rod is fixedly connected with the lower end of the connecting piece.
Further, the electromagnetic pneumatic quasi-zero stiffness vibration isolator with adjustable stiffness further comprises a control system;
the control system comprises a force sensor, an A/D converter, a controller, a signal generator, a power amplifier, an air source control module and an air charging and discharging module;
the force sensor is arranged on the upper part of the load platform and can detect the load mass change on the load platform and generate force change information;
the force sensor is connected with the A/D converter circuit, and the A/D converter receives force change information and converts the force change information into force conversion information;
the A/D converter is in communication connection with the controller, and the controller receives the force conversion information to obtain an air pressure value and a current value;
the air source control module is in communication connection with the controller, and the air charging and discharging module is in circuit connection with the air source control module; the inflation and deflation module is connected with the upper air hole and the lower air hole and can inflate or deflate the upper air hole or the lower air hole; the air source control module receives the air pressure value obtained by the controller and controls the air charging and discharging module to charge air or discharge air into the upper air hole or the lower air hole;
the signal generator is in communication connection with the controller, the signal generator is in circuit connection with the power amplifier, and the power amplifier is in circuit connection with the metal coil; the signal generator receives the current value transmitted by the controller and generates a current signal, and the current signal is amplified by the power amplifier and is respectively transmitted to the 2 metal coils.
The invention designs an electromagnetic pneumatic quasi-zero stiffness vibration isolator with adjustable stiffness, which utilizes the negative stiffness generated by an electromagnetic spring to balance the positive stiffness generated by the pneumatic spring, and realizes that a vibration isolation system is in a quasi-zero stiffness state at a static balance position. When the load changes, the air pressure of the air chamber and the coil current are changed in the same proportion, the working position and the quasi-zero rigidity characteristic of the vibration isolation system can be kept unchanged, and therefore the excellent low-frequency vibration isolation performance is kept. The quasi-zero stiffness vibration isolator has the advantages of wide application range, excellent low-frequency vibration isolation performance, compact structure, simplicity in operation and easiness in control.
Drawings
FIG. 1 shows a cross-sectional view of an adjustable stiffness electro-pneumatic quasi-zero stiffness vibration isolator according to an embodiment of the invention;
FIG. 2 is a graph showing electromagnetic force versus magnet displacement and coil current for an embodiment of the present invention;
fig. 3 shows a stiffness synthesis curve diagram of the electromagnetic pneumatic quasi-zero stiffness vibration isolator with adjustable stiffness according to the embodiment of the invention.
In the figure: 1. a base; 2. a metal coil; 3. a ring magnet; 4. a sleeve; 5. a compression nut; 6. a guide post; 7. a load; 8. a load platform; 9. a first bolt; 10. a connecting rod; 11. a connecting member; 12. a stud bolt; 13. an upper air chamber; 14. a pressure cylinder; 15. air holes are arranged; 16. a piston rod; 17. a lower air chamber; 18. and a lower air hole.
Detailed Description
Exemplary embodiments of the present disclosure will be described in more detail below with reference to the accompanying drawings. While exemplary embodiments of the present disclosure are shown in the drawings, it should be understood that the present disclosure may be embodied in various forms and should not be limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the disclosure to those skilled in the art.
The invention provides an electromagnetic pneumatic quasi-zero stiffness vibration isolator with adjustable stiffness, which comprises a base 1, a load platform 8, 1 group of pneumatic springs and 2 groups of electromagnetic springs, and is shown in figure 1.
The base 1 is provided with 1 group of pneumatic springs and 2 groups of electromagnetic springs, and the pneumatic springs are arranged among the 2 groups of electromagnetic springs; the 2 groups of electromagnetic springs are respectively and fixedly connected with two sides of the stud bolt 12, and the 2 groups of electromagnetic springs can drive the stud bolt 12 to move up and down; the upper end of the pneumatic spring is fixedly connected with the lower end of the connecting piece 11, and the pneumatic spring can drive the connecting piece 11 to move up and down; the connecting member 11 is provided with a through hole into which the stud bolt 12 is fittingly inserted. The upper end of the connecting piece 11 is fixedly connected with the second end of the connecting rod 10, and the first end of the connecting rod 10 is fixedly connected with the lower end of the load platform 8 through the first bolt 9. The connecting rod 10 can enable the load platform 8 to be higher than the electromagnetic spring, and the space range of the load 7 can be enlarged due to the design. The load platform 8 is used for placing the load 7. The connecting piece 11 connects the load platform 8, the electromagnetic spring and the pneumatic spring together to realize the parallel connection of the positive stiffness structure and the negative stiffness structure.
The base 1 upper end both sides are provided with first recess and internal thread, and the centre is equipped with second recess and through-hole.
The 2 electromagnetic springs are symmetrically arranged on two sides of the pneumatic spring along the axis of the pneumatic spring. The electromagnetic spring comprises a sleeve 4, and the sleeve 4 is installed in a first groove of the base 1 in a matching mode. A first space, a second space and a third space are arranged in the sleeve 4 from bottom to top, wherein the first space is the same as the third space, and the diameter of the second space is smaller than that of the first space or the third space; the electromagnetic spring further comprises 2 metal coils 2 and 1 annular magnet 3, both mounted within a sleeve 4. 1 metal coil 2 is respectively installed in first space and the cooperation in the third space, annular magnet 3 is installed in the cooperation of second space. The ring magnet 3 can slide up and down along the inner wall of the second space. Preferably, the height of the second space needs to be set according to the vibration isolation range of the vibration isolator, that is, the movement of the toric magnet 3 is limited within the vibration isolation range. The metal coil 2 is fixed in the first space or the third space by a compression nut 5. The guide post 6 passes through 2 metal coils 2, 1 ring magnet 3 and the compression nut 5. The lower end of the guide post 6 is provided with an external thread which is matched with the internal thread of the base 1 and is in threaded connection. The guide post 6 is screwed with the compression nut 5, thereby being fixedly connected with the sleeve 4. An internal thread is arranged on one side of the annular magnet 3, and the annular magnet 3 is in threaded connection with one side of the stud bolt 12 through the internal thread. Because there are two electromagnetic springs, the stud 12 is connected with the ring magnet 3 on both sides. The lateral wall of the sleeve 4 is provided with a sliding groove, and when the annular magnet 3 slides up and down along the inner wall of the sleeve 4 after the annular magnet 3 is connected with the stud bolt 12, the stud bolt 12 can move along the vertical direction.
The annular magnet 3 is made of neodymium iron boron. The currents of the upper and lower metal coils 2 are direct currents and have the same current direction, the middle annular magnet 3 is attracted mutually to generate negative rigidity, and the negative rigidity is adjustable by changing the coil currents.
The sleeve 4 is made of plastic materials, is arranged in the groove of the base 1, and has a gap of 1mm between the inner wall of the sleeve and the annular magnet for not influencing the movement of the annular magnet 3.
The compression nut 5, the guide post 6 and the stud bolt 12 are made of non-magnetic or weak-magnetic metal materials, and the magnetic field distribution of the metal coil 2 and the annular magnet 3 is not influenced.
The pneumatic spring comprises a pressure cylinder 14, and the pressure cylinder 14 is installed in a second groove of the base 1 in a matching manner; meanwhile, the bottom of the pressure cylinder 14 is provided with a threaded hole which is connected with the through hole of the base 1 through a bolt. A first end of a piston rod 16 is arranged in the pressure cylinder 14, and the first end of the piston rod 16 divides the pressure cylinder 14 into an upper air chamber 13 and a lower air chamber 17; the upper air chamber 13 is provided with upper air holes 15, and the lower air chamber 17 is provided with lower air holes 18. When the piston rod 16 moves, the upper air hole 15 or the lower air hole 18 is in a sealed state, and no air flows in or out. Only when the mass of the load 7 changes will the corresponding gas hole be opened, either for gas inflow or gas outflow. The second end of the piston rod 16 is provided with an internal thread which is fixedly connected with an external thread at the lower end of the connecting piece 11.
Preferably, 8 lower extreme centers of load platform are equipped with the bolt hole, and the first end of connecting rod 10 is provided with the internal thread, and load platform 8 passes through bolt 9 and connecting rod 10 first end fixed connection, and connecting rod 10 second end is equipped with the external screw thread, with the internal thread fixed connection of connecting piece 11 upper end.
The electromagnetic pneumatic quasi-zero stiffness vibration isolator with adjustable stiffness further comprises a control system; the control system comprises a force sensor, an A/D converter, a controller, a signal generator, a power amplifier, an air source control module and an air charging and discharging module. The force sensor is arranged on the upper part of the load platform 8, and can detect the mass change of the load 7 on the load platform 8 and generate force change information; the force sensor is connected with the A/D converter circuit, and the A/D converter receives force change information and converts the force change information into force conversion information; the A/D converter is in communication connection with the controller, and the controller receives the force conversion information to obtain an air pressure value and a current value; the air source control module is in communication connection with the controller, and the air charging and discharging module is in circuit connection with the air source control module; the inflation and deflation module is connected with the upper air hole 15 and the lower air hole 18, and the inflation and deflation module can inflate or deflate the upper air hole 15 or the lower air hole 18; the air source control module receives the air pressure value obtained by the controller and controls the air charging and discharging module to charge air into or discharge air from the upper air hole 15 or the lower air hole 18; the signal generator is in communication connection with the controller, the signal generator is in circuit connection with the power amplifier, and the power amplifier is in circuit connection with the metal coil 2; the signal generator receives the current value transmitted by the controller and generates a current signal, and the current signal is amplified by the power amplifier and is respectively transmitted to the 2 metal coils 2.
When the electromagnetic pneumatic quasi-zero stiffness vibration isolator with adjustable stiffness is in a static balance position, the distances between the annular magnet 3 and the upper and lower metal coils 2 are equal, and the load 7 is completely born by the pneumatic spring. By selecting proper coil current and air pressure of the air chamber, the system can realize the quasi-zero rigidity characteristic at the static balance position, reduce the natural frequency of the system and further improve the low-frequency vibration isolation performance of the system.
The present invention achieves quasi-zero stiffness in the following manner.
(1) When the system bears the mass mg, no coil current is conducted, and only the pressure difference between the upper and lower air chambers of the pressure cylinder 14 is utilized to bear the load. When the air pressure introduced into the upper air chamber and the lower air chamber ensures that the system is in static balance, the distances between the annular magnet 3 and the upper metal coil 2 and the lower metal coil 2 are equal, and the static balance position at the moment is taken as the working position of the vibration isolator. In order to obtain the quasi-zero stiffness characteristic, an exciting current is applied to the metal coil 2, and the positive stiffness generated by the pneumatic spring at the moment is balanced by the negative stiffness generated by the electromagnetic spring, so that the system is in a quasi-zero stiffness state near a static equilibrium position. Because the distance between the annular magnet 3 and the upper and lower 2 metal coils 2 is equal, when the coil current is introduced, the electromagnetic force is 0, the bearing capacity of the pneumatic spring cannot be influenced, and the load is completely borne by the pneumatic spring at the moment. The value of the introduced air pressure and the current value can be calculated.
(2) When the mass of the load 7 is changed, if the mass is increased, and if the air pressures of the upper air chamber and the lower air chamber and the current of the coil are not changed, the position of the load reaching static balance can deviate from the set working position of the vibration isolator, and the vibration isolation performance is reduced. To keep the working position and the quasi-zero stiffness characteristic of the vibration isolation system unchanged, the air pressure and the coil current need to be increased. The force sensor detects the change of the load 7 mass, the signal is transmitted to the controller through the A/D converter, and the controller obtains the required air pressure value and the current value.
(3) The controller transmits the obtained air pressure value to the air source control module, and the air source control module controls the air inflation and deflation module to inflate or deflate the upper air hole 15 or the lower air hole 18, so that the air pressure of the upper air chamber 13 and the lower air chamber 17 is changed, and the working position of the piston rod 16 is kept unchanged. At this time, after the mass of the load 7 is increased, in order to ensure that the static balance position, namely the working position, is not changed, the air pressures of the upper air chamber and the lower air chamber must be increased firstly; the increase in air pressure causes a concomitant increase in the positive stiffness produced by the pneumatic spring.
(4) The current value obtained by the controller is transmitted to the signal generator, the signal generator generates a current signal and inputs the required current into the metal coil 2 through the power amplifier, negative rigidity matched with positive rigidity is generated, the system is guaranteed to still have the quasi-zero rigidity characteristic at the working position, and the vibration isolation system still has excellent low-frequency vibration isolation performance when the load is increased. The person skilled in the art can also deduce how the system achieves a quasi-zero stiffness when the load 7 is reduced in mass.
The present invention calculates the air pressure value and the current value in the following manner.
(1) A group of electromagnetic springs are tested to obtain data of electromagnetic force, displacement and current change of the annular magnet, and a numerical simulation tool is used for fitting the data, wherein the fitting result is as follows:
FES＝(ax3+bx)i
wherein FESIs electromagnetic force between the annular magnet and the upper and lower metal coils; a and b are fitting parameters of a cubic term and a linear term respectively, and are related to the size of the annular magnet, the size and the number of turns of the metal coil, the distance between the upper coil and the lower coil and the like; x is the displacement of the ring magnet from the equilibrium position; i is the magnitude of the current in the metal coil.
Illustratively, the coil current is in the range of 0.2A to 1A, varying at intervals of 0.2A; the distance between the upper metal coil and the lower metal coil is 30mm, the distance between the annular magnet 3 and the lower coil is changed within the range of 2-28mm at intervals of 1mm, the distance between the annular magnet and the lower coil is changed under different current values, data of electromagnetic force along with displacement and current change of the annular magnet are finally obtained, the electromagnetic force change curve is shown in figure 2, matlab software is used for carrying out curve fitting on the data, and F is obtained through fittingESAnd (4) a relational expression.
(2) Based on an ideal gas reversible multivariable equation, the relationship between the restoring force of the pneumatic spring and the displacement of the piston rod is as follows:
Figure BDA0003165448260000081
wherein FpIs the restoring force of a pneumatic spring, pu，pl，Au，Al，huAnd hlThe pressure, the cross section area and the height of the lower air chamber of the upper air chamber are respectively, lambda is a gas polytropic index, and in the adiabatic isentropic process, the lambda is generally 1.4.
(3) 2 groups of electromagnetic springs and 1 group of pneumatic springs are connected in parallel to obtain a quasi-zero stiffness vibration isolation system, and when a load is borne, the restoring force of the system is as follows:
Figure BDA0003165448260000082
wherein FQZSMg is the weight borne, which is the restoring force of the quasi-zero stiffness vibration isolation system.
(4) The restoring force of the vibration isolation system is derived to obtain the rigidity K of the vibration isolation systemQZSAnd the first derivative of stiffness K'QZSComprises the following steps:
Figure BDA0003165448260000091
Figure BDA0003165448260000092
(5) the balance position of the vibration isolation system is arranged at the position where the distance between the annular magnet and the upper and lower metal coils is equal, at the moment, the load is completely born by the pneumatic spring, and the relation between the bearing mass and the air pressure is obtained:
plAl-puAu＝mg
(6) at equilibrium position, the stiffness of the system is zero, which results in:
Figure BDA0003165448260000093
(7) to make the system stiffness at equilibrium position minimum zero, take the first derivative of stiffness to zero:
Figure BDA0003165448260000094
(8) the quasi-zero stiffness condition of the vibration isolation system obtained in the steps (5), (6) and (7) is as follows:
Figure BDA0003165448260000095
the required p for realizing quasi-zero rigidity of the vibration isolation system can be obtained through the steps (5), (6) and (7)u，plAnd i. When the supported weight mg is changed, p after the load change can be obtained by the step (8)u，plAnd i, the working position and the quasi-zero rigidity characteristic of the vibration isolation system are kept unchanged, and the aim that the vibration isolation system can deal with different loads is fulfilled.
In the electromagnetic pneumatic quasi-zero stiffness vibration isolator with adjustable stiffness, the negative stiffness generated by an electromagnetic spring is related to the values of parameters a, b and i, once the metal coil and the annular magnet are designed and assembled, the values of a and b are determined, and the negative stiffness can be changed only by controlling current. After the design of the pneumatic spring is completed, the pneumatic spring generates positive rigidity only equal to the air pressure p of the upper air chamber 13 and the lower air chamber 17u，plIn connection with this, the positive stiffness is controlled by the air pressure of the two chambers. The negative stiffness generated by the electromagnetic spring is connected in parallel with the positive stiffness generated by the pneumatic spring, and the whole system is in a quasi-zero stiffness state near an equilibrium position, as shown in fig. 3.
The invention designs an electromagnetic pneumatic quasi-zero stiffness vibration isolator with adjustable stiffness, which utilizes the negative stiffness generated by an electromagnetic spring to balance the positive stiffness generated by the pneumatic spring, and realizes that a vibration isolation system is in a quasi-zero stiffness state at a static balance position. When the load changes, the air pressure of the air chamber and the coil current are changed in the same proportion, the working position and the quasi-zero rigidity characteristic of the vibration isolation system can be kept unchanged, and therefore the excellent low-frequency vibration isolation performance is kept. The quasi-zero stiffness vibration isolator has the advantages of wide application range, excellent low-frequency vibration isolation performance, compact structure, simplicity in operation and easiness in control.
The above are merely examples of the present application and are not intended to limit the present application. Various modifications and changes may occur to those skilled in the art. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application should be included in the scope of the claims of the present application.

Claims (10)

1. The electromagnetic pneumatic quasi-zero stiffness vibration isolator with the adjustable stiffness is characterized by comprising a base (1);
the base (1) is provided with 1 group of pneumatic springs and 2 groups of electromagnetic springs, and the pneumatic springs are arranged among the 2 groups of electromagnetic springs;
the 2 groups of electromagnetic springs are respectively and fixedly connected with two sides of the stud bolt (12), and the 2 groups of electromagnetic springs can drive the stud bolt (12) to move up and down;
the upper end of the pneumatic spring is fixedly connected with the lower end of the connecting piece (11), and the pneumatic spring can drive the connecting piece (11) to move up and down;
the connecting piece (11) is provided with a through hole, and the stud bolt (12) is inserted into the through hole to be matched with the connecting piece (11);
the upper end of the connecting piece (11) is fixedly connected with the second end of the connecting rod (10), and the first end of the connecting rod (10) is fixedly connected with the lower end of the load platform (8);
the load platform (8) is used for placing a load (7).
2. The adjustable stiffness electro-pneumatic quasi-zero stiffness vibration isolator of claim 1,
the 2 electromagnetic springs are symmetrically arranged on two sides of the pneumatic spring along the axis of the pneumatic spring.
3. The adjustable stiffness electro-pneumatic quasi-zero stiffness vibration isolator of claim 2,
the base (1) upper end both sides are provided with first recess and internal thread, and the centre is equipped with second recess and through-hole.
4. The adjustable stiffness electro-pneumatic quasi-zero stiffness vibration isolator of claim 3,
the electromagnetic spring comprises a sleeve (4), a first space, a second space and a third space are arranged in the sleeve (4) from bottom to top, the first space is the same as the third space, and the diameter of the second space is smaller than that of the first space or the third space;
1 metal coil (2) is respectively installed in the first space and the third space in a matched mode, an annular magnet (3) is installed in the second space in a matched mode, and the annular magnet (3) can slide up and down along the inner wall of the second space;
one side of the annular magnet (3) is fixedly connected with one side of the stud bolt (12);
the sleeve (4) is arranged in the first groove in a matching mode;
the guide post (6) penetrates through the 2 metal coils (2) and the annular magnet (3);
the guide post (6) is fixedly connected with the sleeve (4);
the lower end of the guide post (6) is provided with an external thread which is connected with the internal thread of the base (1).
5. The adjustable stiffness electro-pneumatic quasi-zero stiffness vibration isolator of claim 4,
the electromagnetic spring further comprises a compression nut (5);
the metal coil (2) is fixed by a compression nut (5);
the guide post (6) penetrates through the compression nut (5);
the compression nut (5) is in threaded connection with the guide pillar (6).
6. The adjustable stiffness electro-pneumatic quasi-zero stiffness vibration isolator of claim 5,
an internal thread is arranged on one side of the annular magnet (3), and the annular magnet (3) is in threaded connection with one side of the stud bolt (12) through the internal thread.
7. The adjustable stiffness electro-pneumatic quasi-zero stiffness vibration isolator of claim 6,
the side wall of the sleeve (4) is provided with a sliding groove, and after the annular magnet (3) is connected with the stud bolt (12), the stud bolt (12) can move in the vertical direction.
8. The adjustable stiffness electro-pneumatic quasi-zero stiffness vibration isolator of claim 7,
the current of the 2 metal coils (2) is direct current and the current direction is the same.
9. The adjustable stiffness electro-pneumatic quasi-zero stiffness vibration isolator of claim 8,
the pneumatic spring comprises a pressure cylinder (14), and the pressure cylinder (14) is arranged in a second groove of the base (1);
the bottom of the pressure cylinder (14) is provided with a threaded hole which is connected with the through hole of the base (1) through a bolt;
the first end of the piston rod (16) is arranged in the pressure cylinder (14), and the first end of the piston rod (16) divides the pressure cylinder (14) into an upper air chamber (13) and a lower air chamber (17);
the upper air chamber (13) is provided with an upper air hole (15), and the lower air chamber (17) is provided with a lower air hole (18);
the second end of the piston rod (16) is fixedly connected with the lower end of the connecting piece (11).
10. The adjustable stiffness electro-pneumatic quasi-zero stiffness vibration isolator of claim 9,
the electromagnetic pneumatic quasi-zero stiffness vibration isolator with adjustable stiffness further comprises a control system;
the control system comprises a force sensor, an A/D converter, a controller, a signal generator, a power amplifier, an air source control module and an air charging and discharging module;
the force sensor is arranged on the upper part of the load platform (8), and can detect the mass change of the load (7) on the load platform (8) and generate force change information;
the force sensor is connected with the A/D converter circuit, and the A/D converter receives force change information and converts the force change information into force conversion information;
the A/D converter is in communication connection with the controller, and the controller receives the force conversion information to obtain an air pressure value and a current value;
the air source control module is in communication connection with the controller, and the air charging and discharging module is in circuit connection with the air source control module; the inflation and deflation module is connected with the upper air hole (15) and the lower air hole (18), and the inflation and deflation module can inflate or deflate the upper air hole (15) or the lower air hole (18); the air source control module receives the air pressure value obtained by the controller and controls the inflation and deflation module to inflate or deflate in the upper air hole (15) or the lower air hole (18);
the signal generator is in communication connection with the controller, the signal generator is in circuit connection with the power amplifier, and the power amplifier is in circuit connection with the metal coil (2); the signal generator receives the current value transmitted by the controller and generates a current signal, and the current signal is amplified by the power amplifier and transmitted to the 2 metal coils (2) respectively.
CN202110803090.8A 2021-07-15 2021-07-15 Rigidity-adjustable electromagnetic pneumatic quasi-zero rigidity vibration isolator Pending CN113389843A (en)

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Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN114135630A (en) * 2021-12-10 2022-03-04 武汉理工大学 Quasi-zero stiffness vibration isolator for adjusting balance position by combining air bag and electromagnetism
CN114183495A (en) * 2021-12-10 2022-03-15 中国人民解放军海军工程大学 Quasi-zero stiffness vibration isolator with negative stiffness capable of being adaptively adjusted

Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN114135630A (en) * 2021-12-10 2022-03-04 武汉理工大学 Quasi-zero stiffness vibration isolator for adjusting balance position by combining air bag and electromagnetism
CN114183495A (en) * 2021-12-10 2022-03-15 中国人民解放军海军工程大学 Quasi-zero stiffness vibration isolator with negative stiffness capable of being adaptively adjusted
CN114183495B (en) * 2021-12-10 2023-07-25 中国人民解放军海军工程大学 Quasi-zero stiffness vibration isolator with adaptively-adjustable negative stiffness
CN114135630B (en) * 2021-12-10 2023-10-03 武汉理工大学 Quasi-zero stiffness vibration isolator for adjusting balance position by combining air bag and electromagnetic

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