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CN-121993541-A - Quasi-zero stiffness vibration isolator based on pneumatic-mechanical adjustable combination

CN121993541ACN 121993541 ACN121993541 ACN 121993541ACN-121993541-A

Abstract

The invention discloses a quasi-zero stiffness vibration isolator based on pneumatic-mechanical adjustable compounding, and belongs to the technical field of vibration isolation. The technical scheme is that the vibration isolator comprises an upper connecting plate, a lower connecting plate, a pneumatic positive stiffness module and at least three mechanical negative stiffness modules, wherein the pneumatic positive stiffness module and the mechanical negative stiffness module are arranged in parallel between the upper connecting plate and the lower connecting plate, the pneumatic positive stiffness module forms an adjustable pneumatic sealed air chamber through an air cylinder, a piston and an air pressure adjusting unit to provide nonlinear positive stiffness, the mechanical negative stiffness module adopts a symmetrical diamond connecting rod-spring mechanism to generate negative stiffness near a balance position, and a wide and stable quasi-zero stiffness region is formed near the balance position of a system by accurately matching pneumatic positive stiffness and mechanical negative stiffness curves. The invention has the advantages of online stepless adjustable rigidity, compact structure, stable bearing and excellent low-frequency vibration isolation performance, and is particularly suitable for ultra-low frequency vibration isolation of precision instruments and optical platforms.

Inventors

  • WANG ZHEN
  • YANG ZHE
  • FU WENGUANG
  • Wei Xichu

Assignees

  • 大连大学

Dates

Publication Date
20260508
Application Date
20260213

Claims (10)

  1. 1. A quasi-zero stiffness vibration isolator based on pneumatic-mechanical adjustable compounding, comprising: an upper connecting plate (1) and a lower connecting plate (5); The pneumatic positive stiffness module is arranged in the central area between the upper connecting plate (1) and the lower connecting plate (5) and is used for providing nonlinear positive stiffness; the mechanical negative stiffness modules are uniformly and symmetrically distributed along the circumferential direction and are arranged between the upper connecting plate (1) and the lower connecting plate (5) in parallel; the nonlinear positive stiffness provided by the pneumatic positive stiffness module and the negative stiffness provided by the mechanical negative stiffness module are mutually compensated in a preset displacement range near the balance position of the system, so that the total dynamic stiffness of the vibration isolator in the displacement range is close to zero, and a quasi-zero stiffness zone is formed.
  2. 2. The quasi-zero stiffness vibration isolator based on pneumatic-mechanical tunable composite of claim 1, wherein the pneumatic positive stiffness module comprises: The cylinder body of the cylinder (10) is fixedly arranged on the lower connecting plate (5); The piston (12) is arranged in the cylinder (10) and is precisely matched with the inner wall of the cylinder; the piston (12), the inner wall of the cylinder (10) and the piston rod (2) enclose a closed air chamber with variable volume; The air pressure adjusting unit is connected to the closed air chamber through a pipeline and is used for setting and adjusting the initial absolute pressure in the closed air chamber; And the pressure relief opening (11) is arranged at the upper part of the side wall of the cylinder (10) and is used for preventing the pressure in the closed air chamber from exceeding a safety threshold.
  3. 3. The quasi-zero stiffness vibration isolator based on pneumatic-mechanical adjustable compounding according to claim 2, characterized in that the cylinder (10) is fixed in the central position of the lower connecting plate (5).
  4. 4. The quasi-zero stiffness vibration isolator based on pneumatic-mechanical adjustable composite according to claim 1, wherein the mechanical negative stiffness modules are symmetrical diamond-shaped connecting rod-spring mechanisms and are uniformly and symmetrically distributed along the circumferential direction.
  5. 5. The quasi-zero stiffness vibration isolator based on a pneumatic-mechanical tunable composite according to claim 1 or 4, wherein each of said mechanical negative stiffness modules comprises: Four equal-length connecting rods (9), wherein the connecting rods (9) are connected at the middle parts of the connecting rods through connecting shafts (8) to form an X-shaped structure capable of deforming in a vertical plane; The connecting components are arranged at the upper end and the lower end of the diamond-shaped structure and are used for being connected with the brackets connected with the upper connecting plate (1) and the lower connecting plate (5) respectively; And when the vibration isolator generates vertical displacement, the geometric deformation of the diamond structure enables the component force of the tension spring (4) in the vertical direction to show negative rigidity characteristic.
  6. 6. The quasi-zero stiffness vibration isolator based on pneumatic-mechanical adjustable compounding according to claim 5, wherein the connection assembly comprises a sleeve (6) and a fastening bolt (7), the sleeve (6) and fastening bolt (7) being connected.
  7. 7. The quasi-zero stiffness vibration isolator based on pneumatic-mechanical adjustable compounding according to claim 2, wherein the air pressure regulating unit comprises a micro vacuum/inflator pump, a high precision electrical proportional valve and a pressure sensor.
  8. 8. The quasi-zero stiffness vibration isolator based on pneumatic-mechanical adjustable composite according to claim 2 or 7, wherein the pneumatic positive stiffness module positive stiffness is continuously adjusted on line by adjusting the initial absolute pressure by the pneumatic adjusting unit, so that the quasi-zero stiffness region is reconstructed under different load conditions.
  9. 9. The quasi-zero stiffness vibration isolator based on a pneumatic-mechanical tunable composite of claim 8, further comprising a control system comprising: The pressure sensor is used for monitoring the pressure of the closed air chamber in real time; the device comprises an upper connecting plate (1), a lower connecting plate (5), a displacement sensor used for monitoring the vertical displacement of the upper connecting plate (1) relative to the lower connecting plate (5), and a controller configured to calculate the required target pressure according to the balance position offset caused by load change and control the micro vacuum/inflator pump and the high-precision electric proportional valve to adjust.
  10. 10. The quasi-zero stiffness vibration isolator based on pneumatic-mechanical adjustable compounding according to claim 2, characterized in that the relief vent (11) is connected with a safety valve which automatically opens the relief when the pressure in the sealed air chamber exceeds a preset safety threshold.

Description

Quasi-zero stiffness vibration isolator based on pneumatic-mechanical adjustable combination Technical Field The invention belongs to the technical field of vibration isolation, and particularly relates to a quasi-zero stiffness vibration isolator based on pneumatic-mechanical adjustable compounding. Background The quasi-zero stiffness vibration isolator enables the equivalent stiffness of the system near the balance position to approach zero by connecting elements with negative stiffness and positive stiffness in parallel, so that the effective isolation of low-frequency and even ultra-low frequency vibration is realized. The schemes for realizing quasi-zero rigidity in the prior art mainly comprise the following categories: The mechanical spring scheme has simple structure, but is generally linear in rigidity, a wide frequency quasi-zero region is difficult to independently form, and the rigidity cannot be adjusted in real time. The pre-bending beam structure utilizes the buckling characteristic to generate negative rigidity, but the negative rigidity interval is narrow, and the pre-bending beam structure is extremely sensitive to machining and installation precision and poor in robustness. The magnetic structure utilizes magnetic force to generate negative rigidity, and although non-contact and friction-free can be realized, the magnetic model is complex, high in cost and easy to be interfered by external magnetic fields, and the negative rigidity is difficult to linearly adjust in a large range. The design inspiration of the bionic structure is novel, but a mechanical model is often inaccurate, the performance repeatability is poor, and engineering is difficult. Composite structures can combine a variety of material properties, but are often used to improve damping or strength, making it difficult to achieve accurate, tunable stiffness characteristics as a primary structure. In summary, the existing quasi-zero stiffness vibration isolation technology generally has one or more problems of complex structure, fixed and non-adjustable stiffness characteristics, narrow negative stiffness interval, poor adaptability to load change, large friction or difficult realization of engineering accurate manufacturing. Therefore, there is a need for a quasi-zero stiffness vibration isolator that is relatively simple in structure, independent in positive and negative stiffness, on-line stepless adjustment of positive stiffness, low in friction, high in adaptability, and easy to implement in engineering. Disclosure of Invention The pneumatic-mechanical combined type quasi-zero stiffness vibration isolator provided by the invention has the advantages that the defects of the prior art are overcome, the structure is compact, the positive and negative stiffness characteristics can be independently designed, the positive stiffness can be adjusted in an online stepless manner, a wide and stable quasi-zero stiffness interval can be formed, and the pneumatic-mechanical combined type quasi-zero stiffness vibration isolator is particularly suitable for light-load precise vibration isolation. In order to achieve the above purpose, the present invention provides the following technical solutions: A quasi-zero stiffness vibration isolator based on pneumatic-mechanical tunable compounding comprising: An upper connection plate and a lower connection plate; The pneumatic positive stiffness module is arranged in the central area between the upper connecting plate and the lower connecting plate and is used for providing nonlinear positive stiffness; the mechanical negative stiffness modules are uniformly and symmetrically distributed along the circumferential direction and are arranged between the upper connecting plate and the lower connecting plate in parallel; the nonlinear positive stiffness provided by the pneumatic positive stiffness module and the negative stiffness provided by the mechanical negative stiffness module are mutually compensated in a preset displacement range near the balance position of the system, so that the total dynamic stiffness of the vibration isolator in the displacement range is close to zero, and a quasi-zero stiffness zone is formed. Further, the pneumatic positive stiffness module comprises: the cylinder body of the cylinder is fixedly arranged on the lower connecting plate; the piston is arranged in the cylinder and is in precise fit with the inner wall of the cylinder; The piston, the inner wall of the cylinder and the piston rod enclose a closed air chamber with variable volume; The air pressure adjusting unit is connected to the closed air chamber through a pipeline and is used for setting and adjusting the initial absolute pressure in the closed air chamber; the pressure relief opening is arranged at the upper part of the side wall of the air cylinder and used for preventing the pressure in the closed air chamber from exceeding a safety threshold. Further, the cylinder is fixed at the center of the l