CN115388117A - Horizontal quasi-zero stiffness vibration isolator - Google Patents

Abstract

The invention discloses a horizontal quasi-zero stiffness vibration isolator, which comprises: the inverted pendulum comprises a swinging end and a fixed end, wherein the swinging end is connected with the bearing table through a spherical hinge, and the fixed end is connected with the fixed table through a spherical hinge; the bearing platform is used for bearing instruments, and the fixing platform is connected with a foundation or an aircraft body and a submersible. The bracing piece, with fixed station fixed connection, at least three the bracing piece with the inverted pendulum is central symmetry distribution for the axis, and adjacent two of circumference establish first tie beam between the bracing piece, every first tie beam middle part with all set up the second tie beam between the inverted pendulum. The inverted pendulum provides negative rigidity, and the beam group formed by the at least three groups of the first connecting beams and the second connecting beams provides positive rigidity. The beam group formed by the first connecting beam and the second connecting beam realizes zero-frequency vibration isolation in the horizontal full-circumference direction of the load, the additional damping is small, and the horizontal vibration isolation requirement of high-precision equipment is met.

Description

Horizontal quasi-zero stiffness vibration isolator

Technical Field

The invention relates to the technical field of vibration dampers, in particular to a horizontal quasi-zero stiffness vibration isolator.

Background

The quasi-zero stiffness vibration isolator generally realizes zero stiffness at a balance position by using a negative stiffness structure and a positive stiffness structure which are connected in parallel, so that the natural frequency of the whole structure is close to zero frequency, and low-frequency and ultralow-frequency vibration isolation is realized. High-precision spacecraft, precision instruments and other equipment need to isolate vibration from the outside in different frequencies in the horizontal direction. In addition, the damping of the vibration isolation device should be low, not affecting the damping characteristics of the structure being tested.

The existing vibration isolator is difficult to realize zero-frequency vibration isolation in the horizontal full circumferential direction, the bearing range is difficult to adjust, the additional damping is large, and the requirement of horizontal vibration isolation of high-precision equipment cannot be met.

For example, chinese patent document CN 111237372A discloses a inverted pendulum type quasi-zero stiffness vibration isolator capable of isolating large amplitude low frequency vibration, which achieves vibration isolation by an inverted pendulum that swings back and forth relative to a base plate and a return mechanism installed on the base plate in front of and behind the inverted pendulum, the inverted pendulum disclosed in this document is installed inverted, the vertical position of the inverted pendulum is a balance position, the inverted pendulum deviates from the balance position when being excited, and negative stiffness is generated due to the action of its gravity; reset mechanisms are installed on the front side and the rear side of the inverted pendulum, and torsional springs in the reset mechanisms provide positive rigidity acting force for the inverted pendulum to return to a balance position through reset plates.

Disclosure of Invention

Aiming at the defects of the prior art, the invention discloses a horizontal quasi-zero stiffness vibration isolator which can realize zero-frequency vibration isolation in the whole circumferential direction of the load level, can adjust the bearing range, has smaller additional damping and meets the horizontal vibration isolation requirement of high-precision equipment.

The invention aims to be realized by the following technical scheme, and the horizontal quasi-zero stiffness vibration isolator comprises the following components in percentage by weight:

the inverted pendulum comprises a swinging end and a fixed end, wherein the swinging end is connected with the bearing table through a spherical hinge, and the fixed end is connected with the fixed table through a spherical hinge;

the supporting rods are fixedly connected with the fixed table, at least three supporting rods are distributed in a central symmetry mode by taking the inverted pendulum as an axis, a first connecting beam is arranged between every two circumferentially adjacent supporting rods, and a second connecting beam is arranged between the middle of each first connecting beam and the inverted pendulum;

wherein, the second tie-beam with the tie point of inverted pendulum will the inverted pendulum divide into length for l ₁ And l ₂ Two stages of, adjusting l according to the magnitude of the load ₁ And l ₂ The ratio of (a) to (b).

In one embodiment, the axial direction of the support rod is parallel to the axial direction of the inverted pendulum; and the first connecting beam and the second connecting beam are perpendicular to the axis of the supporting rod.

In one embodiment, the second connecting beam is perpendicular to the first connecting beam.

In a preferred embodiment, the inverted pendulum comprises a first section and a second section, the axes of which coincide and are connected end to end, wherein:

the first section comprises a first head end and a first tail end, the first head end is used as a swinging end of the inverted pendulum and is connected with the bearing platform through a spherical hinge, and the first tail end is connected with the second section of the inverted pendulum;

the second section comprises a second head end and a second tail end, the first head end is connected with the first section of the inverted pendulum, and the second tail end serves as a fixed end of the inverted pendulum and is connected with the first fixed platform through a spherical hinge.

In a preferred embodiment, a first section of the inverted pendulum is connected with a second section through a connecting piece, the second section is fixedly connected with the connecting piece, the first section is connected with the connecting piece through a screw thread, and the distance between the head end of the second section and the head end of the first section is changed by changing the connection length of the screw thread;

wherein the length of the second segment is l ₂ The distance between the head end of the second section and the head end of the first section is l ₁ 。

In a preferred embodiment, the second connecting beam is connected to the inverted pendulum by the connecting element.

In a preferred embodiment, the connecting member includes a plurality of fins, the plurality of fins are arranged in a central symmetry manner with respect to an axis of the second section, and the fins are provided with through holes having axes in a horizontal direction, and the through holes are used for connecting with the second connecting beam.

In one embodiment, the number of the support rods is 4.

In one embodiment, the length of the first connecting beam is twice the length of the second connecting beam, which is connected at the midpoint of the first connecting beam.

In one embodimentIn accordance with

Determining the l ₁ And l ₂ The ratio of (A) to (B);

wherein E is the Young's modulus of the first connecting beam, I is the moment of inertia of the first connecting beam around the vertical direction, L is the length of the second connecting beam, m is the mass of the load, and L = L ₁ +l ₂ 。

The invention discloses a horizontal quasi-zero stiffness vibration isolator, wherein the horizontal direction is a direction vertical to the gravity direction of a load, and the horizontal quasi-zero stiffness vibration isolator comprises: the inverted pendulum comprises a swinging end and a fixed end, wherein the swinging end is connected with the bearing table through a spherical hinge, and the fixed end is connected with the fixed table through a spherical hinge; the bearing platform is used for bearing instruments, and the fixing platform is connected with a foundation or an aircraft body of an aircraft or a submersible. The bracing piece, with fixed station fixed connection, at least three the bracing piece with the inverted pendulum is central symmetry distribution for the axis, and adjacent two of circumference establish first tie beam between the bracing piece, every first tie beam middle part with all set up the second tie beam between the inverted pendulum. The inverted pendulum provides negative rigidity, and the beam group formed by at least three groups of first connecting beams and second connecting beams provides positive rigidity

And then, obtaining the horizontal quasi-zero stiffness vibration isolator, wherein E is the Young modulus of the first connecting beam, I is the inertia moment of the first connecting beam around the vertical direction, L is the length of the second connecting beam, m is the mass of the load, and L is the length of the inverted pendulum. The beam group formed by the first connecting beam and the second connecting beam realizes zero-frequency vibration isolation in the horizontal all-circumferential direction of the load, has small additional damping and meets the horizontal vibration isolation requirement of high-precision equipment.

Further, the connecting point of the second connecting beam and the inverted pendulum divides the inverted pendulum into l length ₁ And l ₂ Two stages of, adjusting l according to the magnitude of the load ₁ And l ₂ The bearing range can be adjusted.

Drawings

Fig. 1 is a schematic overall structural diagram of the horizontal quasi-zero stiffness vibration isolator provided by the invention;

fig. 2 is a schematic overall structural view from another perspective of the horizontal quasi-zero stiffness vibration isolator provided by the invention;

fig. 3 is a schematic view of a partial structure of the horizontal quasi-zero stiffness vibration isolator provided by the invention;

fig. 4 is another partial structural schematic diagram of the horizontal quasi-zero stiffness vibration isolator provided by the invention;

fig. 5, 6 and 7 are mechanical analysis diagrams of the horizontal quasi-zero stiffness vibration isolator provided by the invention.

Detailed Description

The present invention will be described in detail below with reference to the embodiments with reference to the attached drawings. The principles and features of the present invention are described below in conjunction with the drawings, it being understood that the embodiments and features of the embodiments in this application can be combined with each other without conflict. The examples are given solely for the purpose of illustration and are not intended to limit the scope of the invention.

Example 1

High-precision spacecraft, precision instruments and other equipment need to be isolated from vibration of different frequencies in the external horizontal direction. The horizontal quasi-zero stiffness vibration isolator provided by the embodiment can isolate vibration in a direction perpendicular to the gravity direction of a load, and ensures stable working environment of important instruments or structures such as a high-precision spacecraft, a precision instrument or a submersible.

Wherein the horizontal direction refers to a direction in which the direction of gravity of the load is perpendicular.

Specifically, referring to fig. 1 and 2, the horizontal quasi-zero stiffness vibration isolator comprises:

the inverted pendulum 1 comprises a pendulum end and a fixed end, the pendulum end is connected with the bearing platform 2 through a spherical hinge, and the fixed end is connected with the fixed platform 3 through a spherical hinge;

the supporting rods 4 are fixedly connected with the fixed table 3 through angle pieces, at least three supporting rods 4 are distributed in a central symmetry mode by taking the inverted pendulum 1 as an axis, a first connecting beam 5 is arranged between every two circumferentially adjacent supporting rods 4, and a second connecting beam 6 is arranged between the middle of each first connecting beam 5 and the inverted pendulum 1;

wherein, the connecting point of the second connecting beam 6 and the inverted pendulum 1 divides the inverted pendulum 1 into l length ₁ And l ₂ Two stages of, adjusting l according to the magnitude of the load ₁ And l ₂ The ratio of (a) to (b).

The bearing platform 2 of the vibration isolator with the quasi-zero stiffness in the horizontal direction is used for bearing instruments, and the fixed platform 3 is connected with a foundation or an aircraft or a submersible. Specifically, referring to fig. 2, a plurality of load connection holes 201 are provided on the plummer 2 for connecting with an instrument or structure requiring vibration isolation; the fixed platform 3 is provided with foundation bolt holes connected with the foundation or the body of an aircraft or a submersible.

In the embodiment, the swinging end is connected with the bearing table 2 through a spherical hinge, and the fixed end is connected with the fixed table 3 through a spherical hinge; the ball joint connection is preferably realized by a ball head and rod end joint bearing. Referring to fig. 4, specifically, an upper groove 202 is disposed on the lower surface of the bearing platform 2, a ball and socket structure 701 of the ball-rod-end joint bearing is connected and disposed in the upper groove 202, and a ball body 702 of the ball-rod-end joint bearing is connected with the swing end of the inverted pendulum 1; similarly, a lower groove 301 is formed in the upper surface of the fixing table 3, a ball and socket structure 701 for accommodating the ball-rod-end joint bearing is connected in the lower groove 301, and a ball body 702 of the ball-rod-end joint bearing is connected with the fixing end of the inverted pendulum 1.

In the horizontal quasi-zero stiffness vibration isolator provided by the embodiment, the inverted pendulum 1 provides negative stiffness, and the beam set formed by at least three groups of first connecting beams 5 and second connecting beams 6 provides positive stiffness, so that the requirements are met

And then, obtaining the horizontal quasi-zero stiffness vibration isolator, wherein E is the Young modulus of the first connecting beam, I is the inertia moment of the first connecting beam around the vertical direction, L is the length of the second connecting beam, m is the mass of the load, and L is the length of the inverted pendulum.

The beam group formed by the first connecting beam and the second connecting beam realizes zero-frequency vibration isolation in the horizontal full-circumference direction of the load, the additional damping is small, and the horizontal vibration isolation requirement of high-precision equipment is met.

Further, in this embodiment, the connecting point of the second connecting beam and the inverted pendulum divides the inverted pendulum 1 into two parts, i ₁ And l ₂ And can adjust l according to the magnitude of the load ₁ And l ₂ Thereby realizing that the bearing range can be adjusted.

The following provides a structural embodiment of the inverted pendulum 1 to achieve the above-mentioned load-dependent adjustment l ₁ And l ₂ The ratio of (a) to (b). On the basis of fig. 1 and 2, in conjunction with fig. 3, the inverted pendulum 1 includes a first segment 101 and a second segment 102, which are coincident in axis and are connected end to end. Wherein the content of the first and second substances,

a first section 101, including a first head end and a first tail end, the first head end serving as a swing end of the inverted pendulum 1 is connected with the bearing platform 2 by a spherical hinge, and the first tail end is connected with a second section 102 of the inverted pendulum 1;

and the second section 102 comprises a second head end and a second tail end, the first head end is connected with the first section of the inverted pendulum 1, and the second tail end is used as a fixed end of the inverted pendulum 1 and is connected with the first fixed platform 3 by a spherical hinge.

The embodiment also provides a specific implementation manner of a connection structure between the first section 101 and the second section 102 which are connected end to end: the first section 101 and the second section 102 of the inverted pendulum 1 are connected through a connecting piece 103, the second section 102 is fixedly connected with the connecting piece 103, the first section 101 is connected with the connecting piece 103 through threads, and the distance between the head end of the second section 102 and the head end of the first section 101 is changed by changing the connection length of the threads. In this embodiment, the length of the second segment 102 is l ₂ The distance between the head end of the second section 102 and the head end of the first section 101 is l ₁ Then by adjusting l ₁ Can realize the adjustment of ₁ And l ₂ The purpose of the proportion of (A) to adapt to instruments or structures with different weights, and realize quasi-zero rigidity vibration isolation for the instruments or structures.

The above embodiments are only one embodiment provided by the present application that can adjust l ₁ And l ₂ The preferred form of construction of the proportional inverted pendulum, in other embodiments, can be adjusted by adjusting the second segment 102Change in length l ₁ And l ₂ Or by changing l by adjusting the length of the first segment 101 and the second segment 102 ₁ And l ₂ The ratio of (a) to (b).

In a preferred structural form, the second connecting beam 6 is connected with the inverted pendulum 1 through a connecting piece 103, so that the overall structure of the horizontal quasi-zero stiffness vibration isolator is simplified. Under such inventive concept, the present application provides a specific embodiment of the connection member 103:

the connecting member 103 comprises a plurality of fins 1031, the plurality of fins 1031 are arranged in a central symmetry manner relative to the axis of the second section 102, through holes 1033 are arranged on the fins 1031, the axis of each through hole 1033 is in the horizontal direction, and the through holes 1033 are used for being connected with the second connecting beam 6.

In an embodiment with a more simplified structure, the upper end of the connecting member 103 is provided with an internally threaded hole 1032, and the internally threaded hole 1032 is in threaded connection with an external thread on the first tail end of the first segment 101.

The structural form of the horizontal quasi-zero stiffness vibration isolator provided with 4 groups of beam groups consisting of the first connecting beams 5 and the second connecting beams 6 is given in the drawings of the specification of the application, and in fact, 3 groups of beam groups are provided, so that the full-circumferential surrounding of the inverted pendulum 1 can be realized, and the full-circumferential vibration isolation of the horizontal vibration can be realized. If 5, 6 or more beam groups are provided, the vibration isolation effect in each horizontal direction can be realized.

In one embodiment, the axial direction of the support rod 4 is parallel to the axial direction of the inverted pendulum 1; and the first and second connection beams 5 and 6 are perpendicular to the axis of the support bar 4. The second connecting beam 6 is perpendicular to the first connecting beam 5. The number of the supporting rods is 4. The length of the first connection beam 5 is twice the length of the second connection beam 6, and the second connection beam 6 is connected to the midpoint of the first connection beam 5. Under the structural parameters, the mechanical equation of the horizontal vibration isolator provided by the embodiment is analyzed, and the following is:

reference is made to the mechanical analysis chart of the horizontal quasi-zero stiffness vibration isolator shown in figure 5.

The horizontal quasi-zero stiffness structure has the principle as shown in FIG. 5: the rigid inverted pendulum 1 formed by the first segment 101 and the second segment 102 provides negative stiffness,The 4 beam sets provide positive stiffness. The total length of the first section 101 and the second section 102 is l, and the swinging end and the fixed end of the inverted pendulum 1 are respectively provided with a spherical hinge, so that the inverted pendulum 1 can freely rotate in the horizontal direction to form the inverted pendulum. The beam length L of the second connecting beam 6 and the beam length L of the first connecting beam 5 ₀ . The mass of the instrument or structure needing vibration isolation is m, namely the inverted pendulum 1 is subjected to vertical gravity mg, and the horizontal external force causing vibration is F.

And (3) carrying out stress analysis on 4 beam groups:

due to symmetry, two of the adjacent sets of beams are taken for analysis as shown in fig. 6. When subjected to a disturbance displacement X in the X direction _B The stress of the structure can be divided into 2 parts for analysis:

part1 can be regarded as a midspan axial direction x _B The disturbed two ends are fixedly supported on the beam, and the bending strain and the axial strain of part1 are considered, and the stress is

part2 can be regarded as half of an H-shaped beam, and the transverse direction x can be deduced according to a Rayleigh-Ritz method _B Mid-span force displacement curve of H-beam under disturbance containing 3 order terms:

F _h-beam ＝2(K ₁ x _B +K ₃ x _B ³ )

In the formula (I), the compound is shown in the specification,

where E is the young's modulus of the first connection beam, I is the moment of inertia of the first connection beam about the vertical direction (i.e., the Z-axis in fig. 5 and 6), m is the mass of the load, a is the cross-sectional area of the first connection beam, and h is the thickness of the first connection beam.

Thus, part2 is stressed by

Wherein L is ₀ =2L, i.e. L ^* =2, after the insertion, 2 adjacent beam groups at x can be obtained _B Force under disturbance F _B Is expressed as

The whole beam set is fixed at the position B in fig. 6 and 7, and considering the displacement relationship of different points on the inverted pendulum as shown in fig. 7, the total length of the inverted pendulum is set to l = l ₁ +l ₂ ，

Then there is x _B ＝αx，F _A ＝αF _B Therefore, the stress F of 4 beam groups to the point A at the top end can be obtained _A -displacement x-curve:

the inverted pendulum system formed by the first section of rod and the second section of rod is a typical horizontal negative stiffness system, and assuming that the mass of a loaded vibration-isolated object is m, the relational expression between the stress and disturbance displacement is as follows:

the integral combined structure of the inverted pendulum and the beam set has the following relational expression between stress-disturbance displacement:

when the first-order coefficient satisfies:

and the vibration isolator with the quasi-zero stiffness in the horizontal direction can be obtained. According to the formula, when the length of the first section of the inverted pendulum and the length of the second section of the inverted pendulum are changed, so that the proportionality coefficient alpha is changed, quasi-zero stiffness vibration isolation in the horizontal direction can be realized for objects with different bearing masses, and the vibration isolator also has certain bearing range adjustability.

In the description of the present invention, it is to be understood that the terms "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "circumferential", and the like, indicate orientations or positional relationships based on those shown in the drawings, and are only for convenience of description and simplicity of description, and do not indicate or imply that the referenced devices or elements must have a particular orientation, be constructed and operated in a particular orientation, and thus, are not to be construed as limiting the present invention.

In the present invention, unless otherwise expressly stated or limited, the terms "mounted," "connected," "secured," and the like are to be construed broadly and can, for example, be fixedly connected, detachably connected, or integrally formed; can be mechanically or electrically connected; they may be directly connected or indirectly connected through intervening media, or they may be connected internally or in any other suitable relationship, unless expressly stated otherwise. The specific meanings of the above terms in the present invention can be understood by those skilled in the art according to specific situations.

In the present invention, unless otherwise expressly stated or limited, the first feature "on" or "under" the second feature may be directly contacting the first and second features or indirectly contacting the first and second features through an intermediate. Also, a first feature "on," "over," and "above" a second feature may be directly or diagonally above the second feature, or may simply indicate that the first feature is at a higher level than the second feature. A first feature being "under," "below," and "beneath" a second feature may be directly under or obliquely under the first feature, or may simply mean that the first feature is at a lesser elevation than the second feature.

In the description of the specification, reference to the description of "one embodiment," "some embodiments," "an example," "a specific example," or "some examples" or the like means that a particular feature, structure, material, or characteristic described in connection with the embodiment or example is included in at least one embodiment or example of the invention. In this specification, the schematic representations of the terms used above are not necessarily intended to refer to the same embodiment or example. Furthermore, the particular features, structures, materials, or characteristics described may be combined in any suitable manner in any one or more embodiments or examples. Furthermore, various embodiments or examples and features of different embodiments or examples described in this specification can be combined and combined by one skilled in the art without contradiction.

Although embodiments of the present invention have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting the present invention, and that variations, modifications, substitutions and alterations can be made to the above embodiments by those of ordinary skill in the art within the scope of the present invention.

Claims (10)

1. A horizontal quasi-zero stiffness vibration isolator, the horizontal being perpendicular to the direction of gravity of a load, comprising:

the inverted pendulum comprises a swinging end and a fixed end, wherein the swinging end is connected with the bearing table through a spherical hinge, and the fixed end is connected with the fixed table through a spherical hinge;

the supporting rods are fixedly connected with the fixed table, at least three supporting rods are distributed in a central symmetry mode by taking the inverted pendulum as an axis, a first connecting beam is arranged between every two circumferentially adjacent supporting rods, and a second connecting beam is arranged between the middle of each first connecting beam and the inverted pendulum;

wherein the second connectionThe connecting point of the beam and the inverted pendulum divides the inverted pendulum into l parts in length ₁ And l ₂ Two stages of, adjusting l according to the magnitude of the load ₁ And l ₂ The ratio of (a) to (b).

2. The vibration isolator of claim 1, wherein the axis direction of the support rod is parallel to the axis direction of the inverted pendulum; and the first connecting beam and the second connecting beam are perpendicular to the axis of the supporting rod.

3. The horizontal quasi-zero stiffness vibration isolator of claim 2 wherein the second connecting beam is perpendicular to the first connecting beam.

4. The horizontal quasi-zero stiffness vibration isolator of any one of claims 1 to 3 wherein the inverted pendulum comprises first and second segments that are coincident in axis and connected end to end, wherein:

the first section comprises a first head end and a first tail end, the first head end is used as a swinging end of the inverted pendulum and is connected with the bearing platform through a spherical hinge, and the first tail end is connected with the second section of the inverted pendulum;

the second section comprises a second head end and a second tail end, the first head end is connected with the first section of the inverted pendulum, and the second tail end serves as the fixed end of the inverted pendulum and is connected with the first fixed table through a spherical hinge.

5. The vibration isolator as claimed in claim 4, wherein the first segment of the inverted pendulum is connected with the second segment through a connecting piece, the second segment is fixedly connected with the connecting piece, the first segment is connected with the connecting piece through a screw thread, and the distance between the head end of the second segment and the head end of the first segment is changed by changing the connection length of the screw thread;

wherein the length of the second segment is l ₂ The distance between the head end of the second section and the head end of the first section is l ₁ 。

6. The vibration isolator of claim 5 wherein the second connecting beam is connected to the inverted pendulum by the connector.

7. The vibration isolator according to claim 6, wherein the connecting member comprises a plurality of fins, the plurality of fins are arranged in a central symmetry manner with respect to the axis of the second section, and the fins are provided with through holes with axes in the horizontal direction, and the through holes are used for being connected with the second connecting beam.

8. The vibration isolator of claim 3, wherein the number of support rods is 4.

9. The vibration isolator of claim 8 wherein the first connecting beam is twice as long as the second connecting beam, the second connecting beam being connected at a midpoint of the first connecting beam.

10. The horizontal quasi-zero stiffness vibration isolator of claim 9 wherein the stiffness of the base is in accordance with

Determining the l ₁ And l ₂ The ratio of (A) to (B);

wherein E is the Young's modulus of the first connecting beam, I is the moment of inertia of the first connecting beam around the vertical direction, L is the length of the second connecting beam, m is the mass of the load, and L = L ₁ +l ₂ 。

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