A load-adaptive quasi-zero stiffness vibration isolation system

Abstract

The application discloses a load-adaptive quasi-zero-stiffness vibration isolation system, which comprises a diaphragm air spring vibration isolation unit, an external volume adjusting unit and a pressure adaptation module. The diaphragm air spring vibration isolation unit comprises a base, a flexible diaphragm, a sine wave optimized piston and an external guide. On the basis of the diaphragm and the positive stiffness of the gas itself, the continuous change of the effective area is realized by the rolling of the flexible diaphragm between the piston and the external guide to generate negative stiffness. The external volume adjusting unit comprises a fixed volume gas tank and a gas pipeline. By increasing the volume of the diaphragm air spring vibration isolation unit, the positive stiffness of the gas is reduced, and the quasi-zero stiffness is more easily realized. The pressure adaptation module mainly comprises a manual pressure regulator and a one-way stop valve, which is used for adjusting the initial gas pressure in the system, realizing load adaptation and not needing external energy driving. The application realizes the quasi-zero stiffness characteristic by adapting the load change through the gas pressure, combining the balance of the negative stiffness mechanism and the pneumatic stiffness and the diaphragm stiffness.

Description

Technical Field

[0001] This invention relates to the field of vibration control and vibration isolation equipment technology, specifically to a load-adaptive quasi-zero stiffness vibration isolation system. Background Technology

[0002] Low-frequency vibration has a significant impact on the stability, accuracy and service life of engineering structures and precision equipment (Research on vibration reduction mechanism and optimization of QZS vibration isolation platform, Li Jing). Therefore, low-frequency vibration isolation has become a key technical requirement.

[0003] Existing vibration isolation technologies have the following core defects: 1. The inherent contradiction of traditional linear vibration isolators: Linear vibration isolators need to reduce stiffness to achieve effective low-frequency vibration isolation, but low stiffness will cause the system to produce excessive static deformation under its own weight or external load, making it impossible to balance "low-frequency vibration isolation effect" and "static load-bearing capacity", especially unsuitable for high load-bearing scenarios such as aerospace and automobiles; 2. Limitations of Quasi-Zero Stiffness (QZS) Systems: While existing QZS systems can achieve "high static and low dynamic stiffness" through parallel connection of positive and negative stiffness, QZS systems are typical Duffing nonlinear systems with jumps in their amplitude-frequency response curves. This leads to abrupt changes in the system response amplitude, resulting in unstable vibration isolation performance, especially during low-frequency excitation switching. Furthermore, most passive QZS systems are only adaptable to single loads and narrow displacement ranges, and their quasi-zero stiffness characteristics fail when the load changes. If load adaptation is required, it necessitates the use of key components such as springs and permanent magnets. Long-term use may lead to problems such as spring fatigue, permanent magnet demagnetization, and compression instability of inclined springs, resulting in complex structures, increased costs, and dependence on external energy sources. 3. Performance bottlenecks of pneumatic vibration isolators: Although commonly used industrial pneumatic cylinder vibration isolators can approximate near-zero stiffness through external volume, the "stick-slip effect" between the sealing ring and the cylinder wall can lead to unstable motion under low-frequency vibration, destroying the constant force characteristics; although some pneumatic vibration isolators using diaphragms can reduce friction, the stiffness of the diaphragm itself will offset the near-zero stiffness effect; flat sheet diaphragms require large volume to achieve low stiffness, resulting in a bulky structure; corrugated diaphragms have significantly increased stiffness due to the increase in effective area under loading; they cannot meet the comprehensive requirements of "compact structure + near-zero stiffness + low-frequency vibration isolation".

[0004] To address the aforementioned issues, there is an urgent need for a vibration isolation system that requires no external energy drive, maintains near-zero stiffness characteristics over a wide load and large displacement range, and has a compact structure. Summary of the Invention

[0005] The purpose of this invention is to address the problems of existing vibration isolation technologies, such as "conflict between low-frequency vibration isolation and load-bearing capacity," "poor load adaptability," and "requiring active component drive." It provides a load-adaptive quasi-zero stiffness vibration isolation system comprising a diaphragm air spring vibration isolation unit, an external volume adjustment unit, and a pressure adaptation module. These three components work together to bring the total system stiffness close to zero, achieving load-adaptive low-frequency vibration isolation. This invention achieves quasi-zero stiffness characteristics over a wide displacement range and under different load conditions by adapting gas pressure to load changes, combined with a balance between negative stiffness mechanisms, aerodynamic stiffness, and diaphragm stiffness. It can achieve effective vibration isolation from near 2Hz without active control, achieving a comprehensive performance of "no external energy source + wide load adaptability + large displacement quasi-zero stiffness + effective low-frequency vibration isolation." It can be widely applied in aerospace equipment, commercial vehicle suspensions, precision instruments, and other fields with high requirements for low-frequency vibration isolation and load adaptability.

[0006] The present invention is achieved by at least one of the following technical solutions.

[0007] A load-adaptive quasi-zero stiffness vibration isolation system includes a diaphragm air spring vibration isolation unit, an external volume adjustment module, and a pressure adaptation module. The diaphragm air spring vibration isolation unit includes a base, a flexible diaphragm, a piston, and an external guide; wherein the lower end of the piston is bonded to the inner wall of the upper end of the flexible diaphragm to ensure a seamless fit; the lower end of the flexible diaphragm is sealed and bonded to the positioning hole of the base to form a closed air cavity, and the external guide is press-fitted onto the top of the base; The external volume adjustment module is connected in series with the diaphragm air spring vibration isolation unit to reduce the stiffness of the gas spring in order to maintain near-zero stiffness over wide displacement. The pressure adaptation module is used to adjust the internal pressure of the system to achieve load self-adaptation without the need for external energy drive; the three work together to make the total stiffness of the system approach zero, achieving low-frequency vibration isolation.

[0008] Furthermore, the external volume adjustment module includes a fixed volume gas tank and a gas pipeline, with the fixed volume gas tank connected to the pneumatic interface of the base via the gas pipeline.

[0009] Furthermore, a pressure sensor is installed in the gas pipeline connecting the fixed-volume gas tank and the base.

[0010] Furthermore, the pressure adaptation module includes a shut-off valve and a pressure regulator; the input end of the pressure regulator is connected to a pressurized air source, and the output end is connected to the shut-off valve through an air pipe. The shut-off valve is connected to the fixed-volume air tank of the external volume adjustment module through an air pipe.

[0011] Furthermore, the flexible membrane is made of BASF Ultrafuse TPU 95A material, printed in a vase pattern by fused deposition modeling, and then steam smoothed.

[0012] Furthermore, the cross-section of the piston is a superimposed structure of a circular base sinusoidal waveform to achieve matching between the circumference of the flexible membrane and the circumference of the piston along the displacement.

[0013] Furthermore, the guide angle of the external guide is set to 0°, 10° or 20°, and the effective area change rate is controlled by changing the linear change rate of the guide diameter with displacement.

[0014] Furthermore, the piston and external guide structure are made of rigid materials.

[0015] Furthermore, the piston is provided with an extension section that does not contact the TPU membrane, which is used to bear external loads and limit the upward rolling range of the TPU membrane.

[0016] Furthermore, the base is made of 3D printed GreyV4 resin material and integrates pneumatic interfaces and positioning holes, serving as the only communication channel between the internal air chamber and the external air path.

[0017] Compared with existing technologies, the beneficial effects of the present invention are as follows: 1) No energy dependence: No sensors, actuators or external energy are required. Quasi-zero stiffness is achieved only through gas pressure self-balancing and structural geometry optimization, reducing complexity and maintenance costs. 2) Wide load adaptability: Through 1~4 bar pressure adjustment and effective area self-adaptation, it can cover a load range of 15~65kg, with a near-zero stiffness characteristic deviation of <10%, solving the problem of poor load adaptability of traditional QZS systems; 3) Maintaining quasi-zero stiffness during large displacement: After adding an external volume, the quasi-zero stiffness displacement range is expanded to ±15mm, which is 200% higher than the solution without an external volume, meeting the vibration displacement requirements of most engineering equipment. 4) Excellent low-frequency vibration isolation effect: The optimal configuration obtained through experiments (p=4bar, s=10°, Vext=0.75dm³) can achieve effective vibration isolation from a frequency close to 2Hz, with a force transmission rate T<1, which is better than traditional linear vibration isolators.

[0018] 5) Compact structure and easy to manufacture: The core components can be 3D printed, and the overall size is 40% smaller than that of traditional large-volume pneumatic vibration isolators. It can also be quickly adapted to different loads by changing the guide components. Attached Figure Description

[0019] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0020] Figure 1 This is a simplified structural diagram of a load-adaptive quasi-zero stiffness vibration isolation system according to an embodiment.

[0021] Figure 2a This is a structural diagram of the base in an embodiment.

[0022] Figure 2b This is a structural diagram of the flexible diaphragm in the embodiment.

[0023] Figure 2c This is a structural diagram of the sinusoidal piston and its extension section in an embodiment.

[0024] Figure 2d This is a structural diagram of the external guide component in an embodiment.

[0025] Figure 3 This is an assembly diagram of the diaphragm air spring vibration isolation unit in the embodiment.

[0026] Figure 4 This is a cross-sectional view of the sinusoidal waveform optimized piston in the embodiment.

[0027] Figure 5 This is a curve fitting the amplitude formula of the embodiment. Detailed Implementation

[0028] To make the objectives, technical solutions, and advantages of this invention clearer and more explicit, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the implementation of this invention is not limited to the following embodiments, and any modifications and / or alterations made to this invention will fall within the protection scope of this invention. In the description of this invention, it should be understood that directional descriptions, such as up, down, front, back, left, and right, indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. These descriptions are only for the convenience of describing the invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this invention.

[0029] like Figures 1-3 As shown in the figure, this embodiment is a load-adaptive quasi-zero stiffness vibration isolation system, including a diaphragm air spring vibration isolation unit, an external volume adjustment module and a pressure adaptation module, wherein the pressure sensor 4 is only required for the experimental testing phase.

[0030] like Figures 2a-2d As shown, the diaphragm air spring vibration isolation unit is a core carrier with quasi-zero stiffness characteristics. The diaphragm air spring vibration isolation unit 1 includes a base 6, a flexible diaphragm 7, a sinusoidal piston 8, an extension section 9, and a replaceable external guide 10.

[0031] In this embodiment, the flexible diaphragm uses a TPU diaphragm (optimal configuration: air pressure p=4 bar, s=10° in the internal air chamber of the air spring, and volume Vext=0.75 dm³ of the external fixed volume air tank connected to the air spring). The TPU diaphragm uses BASF Ultrafuse TPU 95A material as an example, and is printed with a thickness of 0.4 mm and an effective rolling length of 20 mm through a "vase pattern" of melt deposition molding. It is steam smoothed to balance low stiffness and tear resistance. To solve the problem of sudden increase in stiffness caused by "local accumulation" of the diaphragm on the piston surface, the stiffness of the TPU diaphragm is controlled by the internal pressure of the system. Within the pressure range of 1~4 bar, the diaphragm stiffness decreases as the pressure increases.

[0032] like Figure 3 As shown, specifically, the sinusoidal outer peripheral surface of the lower part of the piston 8 is bonded to the upper inner wall of the TPU diaphragm 7 to ensure a gapless fit; the lower end of the TPU diaphragm 7 is bonded and fixed to the sealing surface of the base 6 to form a sealed air chamber; the external guide 10 is press-fitted to the top of the base 6 to provide rolling trajectory constraint for the TPU diaphragm 7. The extension section 9 is bonded and fixed to the piston 8 with instant adhesive. The extension section 9 does not contact the diaphragm, and its function is to bear external loads and limit the upward rolling limit of the diaphragm.

[0033] The cross-section of the piston 8 is a circular base with a superimposed sine wave structure, and the frequency of the sine wave is... ,amplitude ,in , To achieve displacement of the TPU membrane along its 7-perimeter circumference. Matching the piston circumference 8 prevents the TPU diaphragm 7 from accumulating on the piston surface, avoids diaphragm stress concentration, and prevents a sudden increase in local stiffness.

[0034] The external guide 10 provides the positive and negative stiffness required for vibration isolation and is the core carrier of quasi-zero stiffness characteristics. The guide angle s of the replaceable external guide 10 can be selected as 0°, 10° or 20°. The effective area change rate can be controlled by changing the linear change rate of the guide diameter with the displacement of the piston 8. This allows for adjustment of the gas negative stiffness. It is adapted to the quasi-zero stiffness requirements under different loads.

[0035] In one embodiment, the base 6 is made of 3D printed GreyV4 resin material, integrating a G1 / 8'' pneumatic interface and positioning hole, which is the only communication channel between the internal air chamber and the external air path, and ensures airtightness and installation alignment; the piston 8 and the external guide 10 are both made of rigid materials.

[0036] The external volume adjustment module includes a fixed-volume gas tank 2 and a gas pipeline. The fixed-volume gas tank 2 is connected to a threaded pneumatic interface on the base 6 via a gas pipeline with an outer diameter of 8 mm and an inner diameter of 5.5 mm. The fixed-volume gas tank 2 is connected in series with a diaphragm air spring vibration isolation unit. A pressure sensor 4 is installed on the gas pipeline connecting the fixed-volume gas tank 2 and the base 6. According to the ideal gas law... (in This represents the real-time pressure of the air chambers inside the system. (This is a polytropic index), increasing the external volume can reduce the rate of pressure change. Reduce gas stiffness According to the formula It can reduce the dependence on "effective area change" and enable the quasi-zero stiffness characteristics to be maintained within a displacement range of ±15mm.

[0037] The fixed-volume gas tank 2 has a volume of 0.75~1.0 dm³, with an outer diameter of 8 mm, an inner diameter of 5.5 mm, and a length of 30 cm. The external volume adjustment module reduces the rate of gas pressure change. This extends the quasi-zero stiffness displacement range to ±15mm.

[0038] The pressure adaptation module includes a shut-off valve 3 and a pressure regulator 5. The pressure regulator 5 is located at the very beginning of the gas path, with its input end connected to a pressurized gas source and its output end connected to the shut-off valve 3 via a gas pipe; the shut-off valve 3 is connected to the fixed-volume gas tank 2 via a gas pipe. After the initial gas pressure from the pressurized gas source is input through the pressure regulator 5, the shut-off valve is closed, requiring no external power source and adaptable to different loads.

[0039] The pressure regulator 5 described in this embodiment has an adjustment range of 1~4 bar, and the pressure sensor 4 has an accuracy of ±0.15 bar. The system can be adapted to a load of 15~65 kg by preset pressure. When the load changes, the system maintains quasi-zero stiffness by relying on the self-balancing of gas pressure and effective area.

[0040] Total stiffness of a load-adaptive quasi-zero stiffness vibration isolation system ,in: For the stiffness of the gas spring, Diaphragm stiffness; gas spring stiffness , The positive stiffness contributed to pressure changes. , Negative stiffness contributing to changes in effective area , Let be the absolute pressure of the air chamber inside the air spring, and n be the polytropic exponent, which is taken as n≈1 here; A is the effective pressure-bearing area of ​​the air spring, that is, the effective area where the diaphragm contacts the gas and transmits force; V is the total volume of the air chamber inside the air spring, including the volume of the internal cavity and the external air tank. The nonlinear hyperelastic properties of the TPU diaphragm enable... Decreases as pressure increases; through optimization , and ,make and Equal in size and opposite in direction, ultimately achieving It is close to a near-zero stiffness state.

[0041] Near the equilibrium position, as the load increases, the static displacement of the system increases, and the diaphragm 7 rolls along the piston 8, increasing the effective area. Increase, according to The gas pressure passively increases, and at the same time, according to the formula... As the absolute value of negative stiffness increases, the diaphragm is stretched, and the stiffness... The load decreases as the system enters the "softening zone" of the nonlinear hyperelastic curve, maintaining equilibrium. When the load decreases, the static displacement decreases, and the effective area... Reduce, and the pressure is passively reduced. The absolute value of negative stiffness decreases, while the value increases. The system maintains its balance and near-zero stiffness characteristics. It can achieve effective vibration isolation from frequencies close to 2 Hz, with a force transmissibility T < 1, making it suitable for low-frequency vibration isolation applications in aerospace equipment, commercial vehicle suspensions, or precision instruments.

[0042] The pressure adaptation module of the load-adaptive quasi-zero stiffness vibration isolation system achieves load adaptation through manual preset pressure: based on the load to be isolated. The internal pressure of the air spring flexible diaphragm is set by the pressure regulator 5. After the shut-off valve 3 is closed, the system is in a passive state. When the load changes, the TPU diaphragm 7 deforms, affecting the effective area. By adjusting and combining the self-balancing characteristics of gas pressure, near-zero stiffness can be maintained without active control.

[0043] Specifically, the core of the load-adaptive quasi-zero stiffness vibration isolation system lies in the fact that it does not rely on external power or control, but only on the sinusoidal waveform optimization of the piston geometry and the rolling of the TPU diaphragm 7 between the piston 8 and the external guide 10, so that the "positive stiffness generated by the internal pressure change and the positive stiffness generated by the nonlinear diaphragm" and the "negative stiffness generated by the effective bearing area change" are dynamically canceled out, ultimately achieving quasi-zero stiffness characteristics.

[0044] Furthermore, to ensure that the effective load-bearing area changes in a predictable manner, it is necessary to address the shortcomings of traditional air springs, such as "diaphragm stacking and stretching," and achieve a perfect match between the piston cross-sectional perimeter and the diaphragm annular length under any displacement. The piston of the load-adaptive quasi-zero stiffness vibration isolation system adopts a composite geometry of "circular base + variable amplitude sine wave superposition."

[0045] Specifically, according to Figure 4 It can be seen that the piston base radius is set. ,amplitude The frequency of the superimposed sine wave The perimeters of the piston and the bladder are respectively and Where z is the displacement of the vibration isolator; the circumference of the piston can be obtained as follows: Due to the periodicity of the sine wave, it can be approximated as... ,make = By experimentally measuring the circumference-displacement data of the piston and diaphragm, and fitting the data with a root function, the following results were obtained. ,in , .

[0046] Specifically, by Figure 5 It can be seen that only when the piston's circumference always matches the effective length of the diaphragm as the displacement changes, and the diaphragm does not accumulate and the rolling trajectory is stable, can the change in the effective area be ensured to be controllable.

[0047] The preferred embodiments of the present invention disclosed above are merely illustrative of the invention. These preferred embodiments do not exhaustively describe all details, nor do they limit the invention to the specific implementations described. Clearly, many modifications and variations can be made based on the content of this specification. This specification selects and specifically describes these embodiments to better explain the principles and practical applications of the invention, enabling those skilled in the art to better understand and utilize the invention.

Claims

1. A load-adaptive quasi-zero stiffness vibration isolation system, characterized in that: Includes a diaphragm air spring vibration isolation unit, an external volume adjustment module, and a pressure adaptation module; The diaphragm air spring vibration isolation unit includes a base (6), a flexible diaphragm (7), a piston (8), and an external guide (10); wherein the lower end of the piston (8) is bonded to the upper inner wall of the flexible diaphragm (7) to ensure a seamless fit; the lower end of the flexible diaphragm (7) is sealed and bonded to the positioning hole of the base (6) to form a closed air cavity, and the external guide (10) is pressed onto the top of the base (6); The external volume adjustment module is connected in series with the diaphragm air spring vibration isolation unit to reduce the stiffness of the gas spring in order to maintain near-zero stiffness over wide displacement. The pressure adaptation module is used to adjust the internal pressure of the system to achieve load self-adaptation without the need for external energy drive; the three work together to make the total stiffness of the system approach zero, achieving low-frequency vibration isolation.

2. The load-adaptive quasi-zero stiffness vibration isolation system according to claim 1, characterized in that: The external volume adjustment module includes a fixed volume gas tank (2) and a gas pipeline. The fixed volume gas tank (2) is connected to the pneumatic interface of the base (6) through the gas pipeline.

3. The load-adaptive quasi-zero stiffness vibration isolation system according to claim 1, characterized in that: The gas pipeline connecting the fixed volume gas tank (2) and the base (6) is equipped with a pressure sensor (4).

4. The load-adaptive quasi-zero stiffness vibration isolation system according to claim 1, characterized in that: The pressure adaptation module includes a shut-off valve (3) and a pressure regulator (5); the input end of the pressure regulator (5) is connected to a pressurized air source, and the output end is connected to the shut-off valve (3) through an air pipe. The shut-off valve (3) is connected to the fixed volume air tank (2) of the external volume adjustment module through an air pipe.

5. The load-adaptive quasi-zero stiffness vibration isolation system according to claim 1, characterized in that: The flexible membrane (7) is made of BASF Ultrafuse TPU 95A material, printed in a vase pattern by fused deposition modeling, and then steam smoothed.

6. The load-adaptive quasi-zero stiffness vibration isolation system according to claim 1, characterized in that: The cross-section of the piston (8) is a superimposed structure of a circular base sinusoidal waveform to achieve the matching of the circumference of the flexible membrane along the displacement with the circumference of the piston.

7. The load-adaptive quasi-zero stiffness vibration isolation system according to claim 1, characterized in that: The guide angle of the external guide (10) is set to 0°, 10° or 20°. The effective area change rate is controlled by changing the linear change rate of the guide diameter with displacement.

8. A load-adaptive quasi-zero stiffness vibration isolation system according to claim 1, characterized in that: The piston (8) and the external guide (10) are made of rigid materials.

9. A load-adaptive quasi-zero stiffness vibration isolation system according to claim 1, characterized in that: The piston (8) is provided with an extension section (9), which does not contact the TPU membrane (7) and is used to bear external loads and limit the upward rolling range of the TPU membrane (7).

10. A load-adaptive quasi-zero stiffness vibration isolation system according to claim 1, characterized in that: The base (6) is made of 3D printed GreyV4 resin material and integrates pneumatic interface and positioning hole, which is the only communication channel between the internal air cavity and the external air path.

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