CN112682450A - Vibration isolator with zero-frequency characteristic - Google Patents
Vibration isolator with zero-frequency characteristic Download PDFInfo
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- CN112682450A CN112682450A CN202011426025.XA CN202011426025A CN112682450A CN 112682450 A CN112682450 A CN 112682450A CN 202011426025 A CN202011426025 A CN 202011426025A CN 112682450 A CN112682450 A CN 112682450A
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Abstract
The invention discloses a vibration isolator with zero-frequency characteristic, which has the basic principle that a nonlinear geometric mechanism is formed by four horizontal springs, two vertical springs and four connecting rods, wherein the rigidity of the horizontal springs is half of that of the vertical springs, and the compression amount of the horizontal springs is equal to the length of the connecting rods, so that the vibration isolator with zero rigidity for isolating ultralow-frequency vibration in the vertical direction is designed. The vibration isolator has the characteristics of high static stiffness and low dynamic stiffness near the working balance position, can be applied to vibration isolation of ultralow frequency and large displacement, can effectively reduce the natural frequency of a vibration isolation system, and widens the vibration isolation frequency band. The vibration isolator can be combined with a modal test technology to carry out free state modal test.
Description
Technical Field
The invention belongs to the technical field of ultralow frequency vibration isolation, and particularly relates to a vibration isolator with zero frequency characteristic.
Background
Along with the scale and complexity of engineering technology, the improvement of the performance of vibration isolation equipment is particularly important, and the realization of ultralow frequency vibration isolation becomes one of key and difficult problems of engineering application and scientific research. The actively controlled vibration isolation system is effective for solving low-frequency vibration, but the structure is complex, the manufacturing cost is high, and the actively controlled vibration isolation system is difficult to be widely applied to the engineering field. In the conventional passive vibration isolation system, low-frequency vibration isolation needs to be realized, and the rigidity of the system needs to be reduced, but the reduction of the rigidity can cause the reduction of the bearing capacity and the stability. The quasi-zero stiffness vibration isolator utilizes the parallel connection of the negative stiffness mechanism and the positive stiffness mechanism to construct a system for stabilizing a zero stiffness balance point, and has the characteristics of high static stiffness and low dynamic stiffness. However, when the vibration amplitude of the quasi-zero stiffness vibration isolator is too large or the vibration stroke is large, nonlinear behaviors such as jumping and multi-stable states can be caused, and the vibration isolation effect is influenced. The quasi-zero stiffness vibration isolator in the prior art is difficult to realize real zero stiffness, so the problem of low-frequency resonance still exists.
Disclosure of Invention
The invention aims to provide a vibration isolator with zero-frequency characteristics.
The technical solution for realizing the purpose of the invention is as follows: a vibration isolator with zero-frequency characteristic comprises a supporting base, wherein a vertical shaft is installed in the center of the supporting base, a vertical spring is sleeved on the vertical shaft, the upper end of the vertical spring is a supporting block used for placing a load to be isolated, ball bearings are arranged at two ends of the supporting block, the upper end face of the supporting block is used for placing an isolation load, a vertical linear bearing is installed in an inner hole of the supporting block and sleeved on the vertical shaft, and the upper end of the vertical spring is in contact with the lower end of the supporting block, so that the supporting block can linearly move up and down along; the left end and the right end of the base are structurally symmetrical, a support column is installed at one end of the base, a linear guide rail parallel to the base is installed at the upper part of the support column, a horizontal fixing seat is arranged at one end, away from the vertical shaft, of the linear guide rail, a horizontal shaft is installed on the horizontal fixing seat, and a horizontal sliding seat capable of moving along the linear guide rail is arranged at one end, close to the vertical shaft, of the linear; a horizontal linear bearing is arranged in one end of the horizontal sliding seat, the horizontal linear bearing is sleeved on the horizontal shaft, a ball bearing is arranged in the other end of the horizontal sliding seat, the lower end of the ball bearing is connected with the linear guide rail through a sliding block, and the horizontal fixed seat is connected with the horizontal sliding seat through a horizontal spring, so that the sliding seat can horizontally and linearly move along the horizontal shaft; the ball bearing at one end of the horizontal sliding seat is connected with the ball bearing at one end of the supporting block through the connecting rod, so that the linkage of the horizontal spring, the vertical spring and the vibration isolation load is realized.
Compared with the prior art, the invention has the beneficial effects that: (1) the vibration isolator with the zero-frequency characteristic has the characteristics of high static stiffness and low dynamic stiffness; the static balance position is adjusted by adjusting the spacer, so that the vibration isolator has better rigidity characteristic; (2) the dynamic simulation analysis is carried out on the vibration isolator, and the system has an ideal vibration isolation effect on ultralow-frequency micro-amplitude vibration; experiments prove that the vibration isolator prototype is in a vibration reduction state within the range of (0.2-2000) Hz, and the transmission rate is not greater than 1; (3) the vibration isolator is convenient to process and manufacture, easy to maintain and convenient to install, and is suitable for ultralow-frequency vibration isolation application; (4) the bilateral support parallel zero-stiffness structure can meet the bearing requirement of larger mass or load; (5) according to the force balance relation of the zero stiffness system, when the load changes, the height position of the vertical spring also changes; in the invention, finish machining gaskets with different thicknesses are adopted to finely adjust the reaction force of the vertical spring so as to form a matching relation with different loads.
Drawings
Fig. 1 is a schematic diagram of the vibration isolator with zero frequency characteristic according to the present invention.
Fig. 2 is a schematic view of the whole structure of the vibration isolator with zero-frequency characteristic according to the invention.
Fig. 3 is a three-dimensional view of the vibration isolator having zero frequency characteristics according to the present invention.
Detailed Description
The invention discloses a vibration isolator with zero-frequency characteristic, which is arranged between an object to be isolated and an excitation source, in particular relates to a zero-stiffness vibration isolator with positive stiffness and negative stiffness connected in parallel, and belongs to the technical field of ultralow-frequency vibration isolation.
The vibration isolator has the basic principle that a nonlinear geometric mechanism is formed by four horizontal springs, two vertical springs and four connecting rods, the rigidity of the horizontal springs is half of that of the vertical springs, and the compression amount of the horizontal springs is equal to the length of the connecting rods, so that the zero-rigidity vibration isolator for isolating ultralow-frequency vibration in the vertical direction is designed. The vibration isolator has the characteristics of high static stiffness and low dynamic stiffness near the working balance position, can be applied to vibration isolation of ultralow frequency and large displacement, can effectively reduce the natural frequency of a vibration isolation system, and widens the vibration isolation frequency band. The vibration isolator can be combined with a modal test technology to carry out free state modal test. If the air spring of the electric vibration table is replaced by the zero-rigidity vibration isolator, the electric vibration table can realize a vibration test of (0.2-2000) Hz theoretically, so that the limitation of the ultralow-frequency vibration initial frequency of the electric vibration table is solved, and the market competitiveness of the electric vibration table is improved.
As shown in fig. 1, 2 and 3, a vertical shaft 16 is installed at the center of a support base 1, a vertical spring 17 is sleeved on the vertical shaft 16, an adjusting gasket 18 can be installed at the bottom end of the vertical spring 17 for adjusting the pre-tightening force of the vertical spring 17, a support block 9 for placing a load 8 to be vibration-isolated is arranged at the upper end of the vertical spring 17, ball bearings 11 are arranged at two ends of the support block 9, the upper end face of the support block 9 is used for placing the load 8 to be vibration-isolated, a vertical linear bearing 10 is installed in an inner hole of the support block 9, the linear bearing 10 is sleeved on the vertical shaft 16, and the upper end of the vertical spring 17 is in contact with the lower end of the support block 9, so that the.
The working principle of the vibration isolator is as follows: the vibration-isolated load 8 is installed on the supporting block 9 through a screw, the adjusting gaskets 18 with different thicknesses are replaced, the connecting rod 12 is parallel to the surface of the base 1, the system is in a static balance state, the rigidity of the system is zero, the horizontal spring 5 is in a compression state, and the mass m of the vibration-isolated load 8 is completely supported by the vertical spring 17. When the base 1 generates vibration excitation, the vibration isolator moves up and down, the horizontal sliding seat 7, the sliding block 14 and the ball bearing 13 move left and right at the same time, the compression amount of the horizontal spring 5 is changed, and the motion of the connecting rod can be regarded as rigid plane motion. Namely, the natural frequency of the whole system is very low, so the aim of ultra-low frequency vibration isolation can be achieved.
A mathematical model was established for the vibration isolator and a static analysis was performed, see figure 1. The vertical spring 17 and the horizontal spring 5 have the stiffness K respectivelyvAnd KhX is the compression amount of the horizontal spring, x is λ of the horizontal spring 5 when the system is at the static equilibrium position, the length of the link 12 is L, and Δ y is the displacement of the vibration-isolated load 8 from the static equilibrium position.
The invention provides the following scheme:
the nonlinear restoring force f (y) of the vibration isolation system in the vertical direction is:
F(y)＝2Khxtanθ-Kvy
therefore, the method comprises the following steps:
the total stiffness of the parallel mechanism is then:
to realize ultralow frequency vibration isolation, the total rigidity of the positive and negative rigidity parallel mechanism must be equal to zero, and if L is equal to λ, then:
K＝(Kv-2Kh) 0, i.e. Kv＝2Kh
Introducing dimensionless variables:
the following can be obtained:
k＝0.5，
the system can obtain zero stiffness characteristic. The design takes L ═ lambda ═ 50mm, Kh＝2.5N/m，KvAnd 5N/m, the structure adopting the bilateral support parallel connection can meet the bearing requirement of larger mass or load. The vibration-isolated load 8 is installed on the supporting block 9 through a screw, and the adjusting gaskets 18 with different thicknesses are replaced, so that the connecting rod 12 is parallel to the surface of the base 1, and the system is in a static balance state. Therefore, aiming at any mass of the vibration-isolated load, the system can have the characteristic of zero rigidity by designing the system parameters, thereby realizing ultralow frequency vibration isolation.
The foregoing is only a primary feature, operation principle and advantage of the present invention, and it will be apparent to those skilled in the art that the present invention is not limited by the foregoing embodiments, and that the present invention can be flexibly modified and changed for different embodiments without departing from the basic principle thereof, and such modifications and changes are within the spirit and scope of the present invention.
Claims (7)
1. A vibration isolator with zero-frequency characteristic comprises a supporting base (1) and is characterized in that a vertical shaft (16) is installed at the center of the supporting base (1), a vertical spring (17) is sleeved on the vertical shaft (16), the upper end of the vertical spring (17) is a supporting block (9) used for placing a load (8) to be isolated, ball bearings (11) are arranged at two ends of the supporting block (9), the upper end face of the supporting block (9) is used for placing the load (8) to be isolated, a vertical linear bearing (10) is installed in an inner hole of the supporting block (9), the linear bearing (10) is sleeved on the vertical shaft (16), and the upper end of the vertical spring (17) is in contact with the lower end of the supporting block (9), so that the supporting block (9) can move up and down; the left end and the right end of the base (1) are structurally symmetrical, a support column (2) is installed at one end of the base, a linear guide rail (15) parallel to the base is installed at the upper portion of the support column (2), a horizontal fixing seat (3) is arranged at one end, far away from a vertical shaft (16), of the linear guide rail (15), a horizontal shaft (4) is installed on the horizontal fixing seat (3), and a horizontal sliding seat (7) capable of moving along the linear guide rail (15) is arranged at one end, close to the vertical shaft (16), of the linear guide rail; a horizontal linear bearing (6) is arranged in one end of a horizontal sliding seat (7), the horizontal linear bearing (6) is sleeved on a horizontal shaft (4), a ball bearing (13) is arranged in the other end of the horizontal sliding seat (7), the lower end of the horizontal sliding seat is connected with a linear guide rail (15) through a sliding block (14), and a horizontal fixed seat (3) is connected with the horizontal sliding seat (7) through a horizontal spring (5), so that the sliding seat (7) can horizontally move linearly along the horizontal shaft (4); the ball bearing (13) at one end of the horizontal sliding seat (7) is connected with the ball bearing (11) at one end of the supporting block (9) through the connecting rod (12), so that the linkage of the horizontal spring (5), the vertical spring (17) and the vibration isolation load (8) is realized.
2. The vibration isolator having zero frequency characteristic according to claim 1, characterized in that the bottom end of the vertical spring (17) is mounted with an adjusting shim (18) for adjusting the pre-load of the vertical spring (17).
3. The vibration isolator with zero frequency characteristic according to claim 2, characterized in that the isolated load (8) is mounted on the support block (9) by means of screws.
4. The vibration isolator with zero-frequency characteristic according to claim 3, characterized in that the adjusting shims (18) with different thicknesses are replaced to make the connecting rod (12) parallel to the surface of the base (1), the system is in static equilibrium, the stiffness of the system is zero, the horizontal spring (5) is in compression state, and the mass of the vibration isolation load (8) is completely supported by the vertical spring (17).
5. The vibration isolator according to claim 4, wherein the compression of the horizontal spring at the equilibrium position is equal to the link length.
6. The vibration isolator according to claim 5, wherein each horizontal spring parameter is the same and the horizontal spring rate is half the vertical spring rate.
7. The vibration isolator with zero-frequency characteristic according to claim 1 or 6, characterized in that the number of the horizontal springs (5) is four, the horizontal springs are symmetrically arranged at the left and right ends of the support base (1), and the number of the vertical springs (17) is two.
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| CN202011426025.XA CN112682450A (en) | 2020-12-09 | 2020-12-09 | Vibration isolator with zero-frequency characteristic |
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Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN113501215A (en) * | 2021-07-02 | 2021-10-15 | 宁波格劳博智能工业有限公司 | Intelligent tracing storage and transportation explosion-proof container for power battery |
| CN115325096A (en) * | 2022-08-11 | 2022-11-11 | 郑州轻工业大学 | Constant value quasi-zero stiffness vibration isolation structure based on horizontal tension spring and debugging method |
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| JP2006016935A (en) * | 2004-07-05 | 2006-01-19 | Mitsubishi Heavy Ind Ltd | Base isolation system |
| CN203641365U (en) * | 2014-01-07 | 2014-06-11 | 湖南大学 | Quasi zero stiffness vibration isolator |
| CN106402267A (en) * | 2016-05-23 | 2017-02-15 | 福州大学 | Extension type quasi-zero stiffness vibration isolator and implementation method thereof |
| CN107606038A (en) * | 2017-08-14 | 2018-01-19 | 同济大学 | A kind of non-linear rigidity vibrating isolation system based on hydraulic pressure negative rigidity mechanism |
| CN109751361A (en) * | 2019-01-25 | 2019-05-14 | 哈尔滨工业大学 | A kind of negative stiffness element and negative stiffness characteristic generation method and application with equilbrium position self-regulation ability |
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- 2020-12-09 CN CN202011426025.XA patent/CN112682450A/en active Pending
Patent Citations (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2006016935A (en) * | 2004-07-05 | 2006-01-19 | Mitsubishi Heavy Ind Ltd | Base isolation system |
| CN203641365U (en) * | 2014-01-07 | 2014-06-11 | 湖南大学 | Quasi zero stiffness vibration isolator |
| CN106402267A (en) * | 2016-05-23 | 2017-02-15 | 福州大学 | Extension type quasi-zero stiffness vibration isolator and implementation method thereof |
| CN107606038A (en) * | 2017-08-14 | 2018-01-19 | 同济大学 | A kind of non-linear rigidity vibrating isolation system based on hydraulic pressure negative rigidity mechanism |
| CN109751361A (en) * | 2019-01-25 | 2019-05-14 | 哈尔滨工业大学 | A kind of negative stiffness element and negative stiffness characteristic generation method and application with equilbrium position self-regulation ability |
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN113501215A (en) * | 2021-07-02 | 2021-10-15 | 宁波格劳博智能工业有限公司 | Intelligent tracing storage and transportation explosion-proof container for power battery |
| CN115325096A (en) * | 2022-08-11 | 2022-11-11 | 郑州轻工业大学 | Constant value quasi-zero stiffness vibration isolation structure based on horizontal tension spring and debugging method |
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