A negative stiffness spring structure for large load micro-vibration

Abstract

The present invention relates to a negative stiffness spring structure for large-load micro-vibration, which uses a continuum structure with fully flexible joints, specifically uses a negative stiffness technology based on the triangle principle to achieve negative stiffness. In order to solve the limitation of the compressive stress of the buckling beam in the process of realizing the negative stiffness of the continuum, further improve the negative stiffness coefficient and reduce the additional positive stiffness of the material, a full tensile stress negative stiffness structure is designed by combining the flip plate structure with the triangle structure. It can be used to match high-stiffness springs, effectively reduce the natural frequency of the vibration isolation system composed of isolators such as coil springs and air springs, and is particularly suitable for heavy-load micro-vibration low-frequency vibration isolation occasions.

Description

Technical Field

[0001] The invention belongs to the field of shock absorbing devices and is applied to ultra-low frequency vibration isolation systems of large precision instruments in isolating ground micro-vibrations. Specifically, the invention relates to a negative stiffness spring structure for large-load micro-vibrations. Background Art

[0002] Large precision instruments need to be isolated from low-frequency micro-vibrations on the ground during use. At present, large precision equipment mainly uses a vibration isolation system consisting of an air spring and an external air chamber. The defects of the existing technology mainly include the following aspects: 1. The rubber membrane of the large-load air spring is thick, and the rubber membrane introduces a large stiffness; 2. The stiffness of the high-pressure compressed air in the air spring is large, and the stiffness of the air spring is related to the height of the cylinder. The vibration isolation system of precision equipment does not want to have a high center of mass, so the stiffness of the air spring is difficult to further reduce; 3. The natural frequency of the vibration isolation system is relatively high, and the frequency distance from the ground pulsation frequency and the ground low-frequency transmission advantage frequency cannot be well widened, resulting in unsatisfactory vibration isolation performance. Summary of the Invention

[0003] The purpose of the present invention is to overcome the shortcomings of the existing technology and provide a negative stiffness spring structure for large load micro-vibration. The structure is designed according to the large working load requirements and micro-vibration requirements, mainly avoiding compressive stress and reducing the stiffness of the flexible joint.

[0004] The present invention solves the technical problem by adopting the following technical solutions:

[0005] A negative stiffness spring structure for large-load micro-vibration, characterized in that it includes a horizontal spring, a horizontal spring compression adjustment mechanism, a force transmission frame, a short tensile beam, a flip plate, a long tensile beam and a flexible hinged strut. A limit frame is fixedly installed on the ground foundation, and a horizontal spring is installed for limit adjustment in the middle of the limit frame. One axial end of the horizontal spring is connected to the horizontal spring compression adjustment mechanism, and the other axial end of the horizontal spring is connected to the force transmission frame. A horizontally arranged short tensile beam is installed in the middle of the force transmission frame. A flip plate is symmetrically installed on both sides of the force transmission frame. The flip plate is flexibly connected to the force transmission frame. The right end of the flip plate is connected to the long tensile beam. Flexible hinged struts are installed at the upper end of the flip plate, and the upper end of the flexible hinged strut is connected to the air spring mounting plate.

[0006] Moreover, the flip plate is connected to the force transmission frame through a short beam with a flexible joint, and the bottom of the flip plate is connected to the ground foundation through a beam with a flexible joint.

[0007] Moreover, the horizontal spring compression adjustment mechanism includes a stand, a threaded rod, a wedge block and a spring sleeve. The stand is fixed on the ground foundation. A vertically set threaded rod is installed on one side of the stand. The lower part of the threaded rod engages with a wedge block. The wedge block is made with an inclined slope, which cooperates with the inclined slope at the end of the spring sleeve. The spring sleeve is slidingly limited and installed in the middle through hole of the limit frame. A horizontal spring is installed in the spring sleeve. The threaded rod is rotated to adjust the wedge block to move up and down, and the spring sleeve is adjusted to move in the horizontal direction.

[0008] Moreover, the short tensile beam is a thin plate or a rope, and only bears tension inside. During the vibration process, the beam rotates and flexes.

[0009] Moreover, the long tensile beam is a thin plate or rope, and only bears tension inside. During the vibration process, the beam rotates and flexes. The left end of the long tensile beam is fixed to the ground foundation, and the right end of the long tensile beam is connected to the flip plate.

[0010] Moreover, a flexible beam of a turning plate rotating shaft is installed between the turning plate and the ground foundation at the connection end of the turning plate and the force transmission frame.

[0011] Moreover, flexible joint struts are installed between the opposite ends of the force transmission frame and the ground foundation.

[0012] The advantages and positive effects of the present invention are:

[0013] 1. This structure is a continuum, without bearings, joints, or other mechanical kinematic pairs. This eliminates the impact of nonlinear factors such as contact and friction on micro-vibrations. Therefore, this vibration isolation system can be used to isolate micro-vibrations. By utilizing springs and a frame structure to transmit horizontal spring force, which is converted into a thin plate bearing tensile stress, this improves the structure's load-bearing capacity while reducing torsional stiffness. Therefore, converting compressive stress into tensile stress is a key innovation in structural design.

[0014] 2. In this structure, the flip plate is actually the short side of the triangle with negative stiffness. One side of the flip plate is the negative stiffness effect point, and the other side needs to have horizontal movement and rotation capabilities. Flexible joint struts are used in the design of this negative stiffness structure to enable the flip plate to have the above functions and have the characteristics of being able to resist micro-vibration.

[0015] 3. The negative stiffness part of this structure is entirely made of tensile beams, avoiding the compressive stress buckling beams used in the negative stiffness of typical structures, and avoiding the contradiction between torsional stiffness and bearing capacity caused by buckling beams.

[0016] 4. This structure has a large negative stiffness. The negative stiffness structure based on full tensile stress can make the negative stiffness have a large working load and obtain a large negative stiffness. It can be used to match the large stiffness spring and effectively reduce the natural frequency of the vibration isolation system composed of vibration isolators such as coil springs and air springs. It is particularly suitable for heavy-load micro-vibration and low-frequency vibration isolation occasions. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 This is a schematic diagram of the structure;

[0018] Figure 2 yes Figure 1 BB cross-sectional view;

[0019] Figure 3 This is a three-dimensional diagram of the structure;

[0020] Figure 4 yes Figure 2 A magnified schematic diagram of part A in FIG;

[0021] Figure 5 It is a schematic diagram of the triangle negative stiffness principle. DETAILED DESCRIPTION

[0022] The present invention will be further described in detail below with reference to the accompanying drawings and through specific embodiments. The following embodiments are merely illustrative and non-restrictive, and the scope of protection of the present invention cannot be limited thereto.

[0023] The present invention solves the technical problem by adopting the following technical solutions:

[0024] A negative stiffness spring structure for large load micro-vibration, comprising a horizontal spring 2, a horizontal spring compression adjustment mechanism 1, a force transmission frame 3, a short tensile beam 8, a flip plate 7, a long tensile beam 9 and a flexible hinged support rod 5. Figure 2 The direction shown describes the left and right. A limit frame 10 is fixed on the ground foundation 12. A horizontal spring is installed in the middle of the limit frame for limit adjustment. One axial end of the horizontal spring is connected to the horizontal spring compression adjustment mechanism, and the other axial end of the horizontal spring is connected to the force transmission frame.

[0025] A short tensile beam is installed horizontally in the middle of the force transmission frame. The short tensile beam is a thin plate or rope, and only bears tension inside. During the vibration process, the beam rotates and flexes. The horizontal spring transmits the spring force to the short tensile beam through the force transmission frame, and the spring thrust is converted into tension in the short tensile beam.

[0026] A flip plate is symmetrically installed on both sides of the force transmission frame. The flip plate is connected to the force transmission frame through a short beam with a flexible joint, and the bottom of the flip plate is connected to the ground foundation through a beam with a flexible joint.

[0027] The right end of the flip plate is connected to the long tensile beam, which is installed on the outside of the flip plate. The left end of the long tensile beam is fixed to the ground foundation. The flip plate uses the left end as the axis, and the right end can flip up or down.

[0028] The long tensile beam, the long side of the triangular negative stiffness structure, is made of thin plates or ropes. It bears only tension internally, but rotates and flexes during vibration. Its left end is fixed to the foundation, and its right end is connected to the flip plate.

[0029] A flip plate rotation axis flexible beam 4 is installed between the flip plate and the ground foundation at the connection end of the flip plate and the force transmission frame. The flip plate rotation axis flexible beam provides vertical support for the flip plate.

[0030] A flexible joint strut 6 is installed between the right end of the force transmission frame and the ground foundation. The flexible joint strut limits the frame structure to have only horizontal translation, has a small horizontal stiffness, has a supporting effect in the upward and downward directions, and has a large stiffness.

[0031] Flexible hinged struts 5 are mounted at the upper ends of the flip plates. Their upper ends are connected to air spring mounting plates 11, which are used to mount air springs. These hinged struts transfer vertical negative stiffness to the air springs while maintaining minimal horizontal stiffness. The hinged struts are mounted at the structural equilibrium point, and the flip plates serve as the short sides of a triangle to achieve negative stiffness relative to the equilibrium point.

[0032] The horizontal spring, long tensile beam and flip plate are as shown in the attached Figure 5 The triangular negative stiffness structure shown.

[0033] The horizontal spring compression adjustment mechanism provides preload adjustment for the horizontal spring. Figure 4 As shown, the horizontal spring compression adjustment mechanism includes a stand 1-4, a threaded rod 1-1, a wedge 1-3, and a spring sleeve 1-2. The stand is fixed to the ground foundation. A vertically mounted threaded rod 1-1 is positioned on one side of the stand. The lower portion of the threaded rod engages a wedge 1-3, which has an inclined slope that mates with the inclined slope at the end of the spring sleeve 1-2. The spring sleeve is slidably mounted within a central through-hole in the stop frame, and a horizontal spring is mounted within the spring sleeve. Rotating the threaded rod to adjust the wedge's vertical movement adjusts the horizontal movement of the spring sleeve.

[0034] This structure utilizes a fully tensile structure to eliminate the buckling rod in a typical negative stiffness structure, thereby increasing the working load and reducing the rotational stiffness.

[0035] Although the embodiments and drawings of the present invention are disclosed for illustrative purposes, those skilled in the art will understand that various substitutions, changes and modifications are possible without departing from the spirit and scope of the present invention and the appended claims. Therefore, the scope of the present invention is not limited to the contents disclosed in the embodiments and drawings.

Claims

1. A negative stiffness spring structure for large load micro-vibration, characterized in that: It includes a horizontal spring, a horizontal spring compression adjustment mechanism, a force transmission frame, a short stretching beam, a flip plate, a long stretching beam and a flexible hinged support rod. A limit frame is fixed on the ground foundation. A horizontal spring is installed in the middle of the limit frame for limit adjustment. One axial end of the horizontal spring is connected to the horizontal spring compression adjustment mechanism, and the other axial end of the horizontal spring is connected to the force transmission frame. A short tensile beam is installed horizontally in the middle of the force transmission frame. The short tensile beam is a thin plate or rope, and only bears tension inside. During the vibration process, the beam rotates and flexes. The horizontal spring transmits the spring force to the short tensile beam through the force transmission frame, and the spring thrust is transmitted to become the tension of the short tensile beam. A flip plate is symmetrically installed on both sides of the force transmission frame. The flip plate is connected to the force transmission frame through a short beam with a flexible joint, and the bottom of the flip plate is connected to the ground foundation through a beam with a flexible joint. The right end of the flip plate is connected to the long stretching beam, which is installed on the outside of the flip plate. The left end of the long stretching beam is fixed on the ground foundation. The flip plate takes the left end as the axis, and the right end can flip upward or downward. The long tensile beam is the long side of the triangular negative stiffness structure. It is made of thin plates or ropes and only bears tension inside. During the vibration process, the beam rotates and flexes. The left end of the long tensile beam is fixed on the ground foundation, and the right end of the long tensile beam is connected to the flip plate. A flexible beam for the rotating shaft of the flip plate is installed between the flip plate and the ground foundation at the connection end of the flip plate and the force transmission frame, and the flexible beam for the rotating shaft of the flip plate provides vertical support for the flip plate. A flexible joint strut is installed between the right end of the force transmission frame and the ground foundation. The flexible joint strut limits the frame structure to have only horizontal translation, has a small horizontal stiffness, has a supporting effect in the upward and downward directions, and has a large stiffness; Flexible hinged struts are installed at the upper end of the flip plate, and the upper end of the flexible hinged struts is connected to the air spring mounting plate. The air spring mounting plate is used to install the air spring. The flexible hinged struts can transfer vertical negative stiffness to the air spring and have a smaller horizontal stiffness. The installation position of the flexible hinged struts is the structural balance point, and the flip plate is used as the short side of the triangle to achieve negative stiffness to the balance point.

2. The negative stiffness spring structure for large load micro-vibration according to claim 1, characterized in that: The horizontal spring compression adjustment mechanism includes a stand, a threaded rod, a wedge block and a spring sleeve. The stand is fixed on the ground foundation. A vertically arranged threaded rod is installed on one side of the stand. A wedge block is engaged with the lower part of the threaded rod. The wedge block is provided with an inclined slope, which cooperates with the inclined slope at the end of the spring sleeve. The spring sleeve is slidingly limited and installed in the middle through hole of the limit frame. A horizontal spring is installed in the spring sleeve. The threaded rod is rotated to adjust the wedge block to move up and down, thereby adjusting the spring sleeve to move in the horizontal direction.

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