Compact adjustable stiffness large load isolation connection structure of beam-ball cooperation

Abstract

A compact, adjustable stiffness, high-load vibration isolation connection structure with beam-sphere cooperation includes: a preload adjustment pad, an elastic rubber ball, and an arc-shaped metal beam assembly, arranged sequentially from bottom to top within a base and a housing, and an upper connecting assembly connected to the arc-shaped metal beam assembly. The upper end of the elastic rubber ball contacts the upper connecting assembly, and the lower end contacts the preload adjustment pad. By replacing the pad with pads of different thicknesses, the initial compression of the rubber ball can be changed, thereby adjusting the overall stiffness characteristics of the connector. When the base and the bottom of the housing are excited, the arc-shaped metal beam assembly bends and deforms, exhibiting negative stiffness characteristics, while the elastic rubber ball exhibits positive stiffness characteristics, thus harmonizing the two. This results in the system exhibiting low or near-zero stiffness, effectively reducing the system's natural frequency and broadening the vibration isolation frequency band. This invention achieves adjustable stiffness and low-frequency vibration isolation by changing the preload of the elastic ball.

Description

Technical Field

[0001] This invention relates to a technology in the field of mechanical vibration isolation, specifically a compact, adjustable stiffness, high-load vibration isolation connection structure with beam-sphere cooperation. Background Technology

[0002] Existing rigid connection methods easily transmit the basic excitation directly to the connected components, causing resonance and other problems. Passive vibration isolation elements (such as rubber pads and springs) have fixed stiffness and cannot adapt to varying operating conditions, posing a risk of resonance at specific frequencies. Existing rubber spring vibration isolation technology relies solely on the compression of the rubber spring itself to provide positive stiffness, without involving any negative stiffness mechanism, and cannot achieve quasi-zero stiffness characteristics. Furthermore, existing three-degree-of-freedom vibration isolation technology has a complex structure and requires external power supply and control system, making it impossible to achieve purely mechanical, passive, and adjustable stiffness under high loads; at the same time, its quasi-zero stiffness bandwidth is narrow, making it difficult to cover the low-frequency range. Summary of the Invention

[0003] To address the aforementioned shortcomings of existing technologies, this invention proposes a compact, adjustable stiffness, high-load vibration isolation connection structure with beam-sphere synergy. By changing the preload of the elastic sphere, adjustable stiffness and low-frequency vibration isolation effects are achieved.

[0004] This invention is achieved through the following technical solution:

[0005] This invention relates to a compact, adjustable stiffness, high-load vibration isolation connection structure with beam-ball coordination, comprising: a preload adjustment pad, an elastic rubber ball, and an arc-shaped metal beam assembly arranged sequentially from bottom to top within a base and a housing, and an upper connecting assembly connected to the arc-shaped metal beam assembly. The upper end of the elastic rubber ball contacts the upper connecting assembly, and the lower end contacts the preload adjustment pad. By replacing pads of different thicknesses, the initial compression of the rubber ball can be changed, thereby adjusting the overall stiffness characteristics of the connector. When the base and the bottom of the housing are excited, the arc-shaped metal beam assembly undergoes bending deformation and exhibits negative stiffness characteristics, while the elastic rubber ball exhibits positive stiffness characteristics and harmonizes with this, resulting in a system exhibiting low or near-zero stiffness overall, thereby effectively reducing the system's natural frequency and widening the vibration isolation frequency band.

[0006] Technical effect

[0007] The rubber sphere of this invention exhibits gradually hardening positive stiffness during compression, which can harmonize the negative stiffness of the metal beam, achieving nonlinear stiffness characteristics of high static stiffness and low dynamic stiffness. This enables the system to achieve vibration isolation effects over a wide frequency range. By adjusting the pre-compression of the rubber sphere, the connector can switch between different stiffness states to adapt to vibration isolation requirements under different operating conditions. Attached Figure Description

[0008] Figure 1 This is a schematic diagram of the structure of the present invention;

[0009] In the diagram: 1. Base and outer casing; 2. Upper connecting components;

[0010] Figure 2 This is a schematic diagram of the interior of the present invention after the base and outer shell have been removed;

[0011] In the diagram: 3. Arc-shaped metal beam assembly; 4. Elastic rubber ball; 5. Preload adjustment pad.

[0012] Figure 3 This is a cross-sectional view of the present invention;

[0013] Figure 4 This is an exploded view of the present invention;

[0014] In the diagram: 101 base, 102 outer shell, 201 upper component threaded plate, 202 upper component fixing plate, 203 elastic ball pressure plate, 301 arc-shaped metal beam, 302 metal beam pressure plate, 303 cross fastener, 4 elastic rubber ball, 5 pre-pressure adjustment pad.

[0015] Figure 5 (a) is a schematic diagram of the initial shape of the elastic rubber ball under different preload adjustment amounts;

[0016] Figure 5 (b) is a schematic diagram of the restoring force of the elastic rubber ball under different preload adjustment amounts;

[0017] Figure 6 A schematic diagram showing the overall stiffness characteristics of the vibration isolation connector under different preload adjustments;

[0018] Figure 7 A schematic diagram of the frequency domain vibration transmissivity of the vibration isolation connector calculated using simulation software under different preload adjustment amounts; Figure 8 The acceleration transfer curves obtained from the test in this example are shown. Detailed Implementation

[0019] like Figure 1 and Figure 2 As shown, this embodiment relates to a compact adjustable stiffness high-load vibration isolation connection structure with beam-ball coordination, including: a pre-compression adjustment pad 5, an elastic rubber ball 4, and an arc-shaped metal beam assembly 3 arranged sequentially from bottom to top in the base and the outer shell 1, and an upper connecting assembly 2 connected to the arc-shaped metal beam assembly 3.

[0020] like Figure 3As shown, the upper connecting component 2 includes: an upper component threaded plate 201, an upper component fixing plate 202, and an elastic ball pressure plate 203 connected in sequence. The upper component threaded plate 201 is bolted to the bottom of the large load component. The upper component fixing plate 202 and the elastic ball pressure plate 203 are connected by a cross fastener 303, and the lower end of the upper component fixing plate 202 and the upper end of the elastic ball pressure plate 203 together clamp the middle part of the arc-shaped metal beam 301.

[0021] The upper component threaded plate 201 is fixedly connected to the upper component fixing plate 202 by four M4 hexagon socket bolts.

[0022] The elastic ball pressure plate 203 has a flat groove at its upper end, and a flat groove and a cross-shaped fixing member 303 are provided at the lower end of the corresponding component fixing plate 202 to achieve clamping of the arc-shaped metal beam 301.

[0023] The lower end of the elastic ball pressure plate 203 is flat and directly contacts the elastic rubber ball 4, ensuring uniform pressure transmission.

[0024] The base and outer shell 1 include: a base 101 made of aluminum alloy and an outer shell 102 connected thereto.

[0025] The base 101 has a Φ10.2mm through hole at its bottom for connection to the external main frame via M10 bolts. An adjusting pad 5 and an elastic rubber ball 4 are sequentially arranged inside the base.

[0026] The base and base 101 below the pre-pressure adjusting pad 5 are provided with flat grooves to clamp the arc-shaped metal beam.

[0027] The outer shell 102 is a plastic printed part with through holes at the four corners. It is fixed to the base 101 by four M4 bolts to seal the internal structure, prevent dust and oil from entering, and at the same time play a protective role.

[0028] like Figure 4 As shown, the arc-shaped metal beam assembly 3 includes: two intersecting arc-shaped metal beams 301 and four metal beam pressure plates 302 respectively disposed at their ends, wherein: the middle section of the arc-shaped metal beam 301 is arc-shaped and is fixedly connected to the base and the outer shell 1 through the metal beam pressure plates 302 at both ends.

[0029] The metal beam is made of 65Mn spring steel strips, with a thickness of 0.45mm and a width of 10mm.

[0030] The arc has a radius R1 = 60mm, a central angle of 120°, and a straightening length of 10mm at both ends for fixing.

[0031] The lower part of the metal beam pressure plate 302 has a flat groove slightly wider than the beam, with a width of 10.2mm. Each end of the pressure plate is fixed with an M3 bolt. The two beams are arranged at a 90° angle, with the intersection point located at the center. They are clamped by a cross-shaped fastener 303. The center of the cross-shaped fastener has a Φ3.2mm through hole, which cooperates with the bolt of the elastic ball pressure plate 203 to ensure a rigid connection between the middle of the beam and the upper connecting assembly.

[0032] The elastic rubber ball 4 is made of silicone rubber with a Shore hardness of 50A and a diameter D=50mm. Upon compression, the ball exhibits gradually hardening positive stiffness characteristics, and its force-displacement relationship is as follows: Figure 5 As shown.

[0033] The pre-pressure adjusting pad 5 is an annular metal sheet with an outer diameter of 60mm, an inner diameter of 20mm, and a thickness of 1mm, 2mm, 3mm, etc., and is made of 304 stainless steel.

[0034] This embodiment is assembled in the following manner: the base 101 is fixed to the external overall frame through the bottom mounting hole, and the pre-pressure adjustment pad 5 is placed in it; the elastic rubber ball 4 is placed in the center of the pad; two arc-shaped metal beams 301 are placed crosswise and temporarily fixed in the middle with a cross fastener 303; the upper component fixing plate 202 is placed on the upper arc-shaped metal beam and aligned with the flat groove; the elastic ball pressure plate 203 is placed below the lower arc-shaped metal beam; the upper component threaded plate 201 is placed at the top, and an M3 plug bolt is passed through the center hole to tighten the upper component threaded plate, upper component fixing plate, upper arc-shaped metal beam, cross fastener, lower arc-shaped beam and elastic ball pressure plate in sequence, so that the middle of the beam is reliably clamped; the two ends of the beam are aligned with the installation position on the base and pressed with the metal beam pressure plate 302 and M3 bolts, taking care to keep the beam symmetrical; the outer shell 102 is installed and fixed to the base with four M4 bolts; the heavy load component is placed on the connector and connected to it through the threaded hole of the upper component threaded plate.

[0035] like Figure 5 As shown, when an external vertical vibration excitation is applied to the base 101, the arc-shaped metal beam 301 undergoes bending deformation, and its force-displacement curve exhibits negative stiffness characteristics. Figure 6 The red line represents the region shown in the diagram. Within this specific area, the positive stiffness of the elastic rubber ball balances the negative stiffness of the metal beam, resulting in a low-stiffness region suitable for broadband vibration isolation of heavy-load components. The elastic rubber ball 4 exhibits gradually hardening positive stiffness under pressure. Figure 6 The blue, yellow, and purple lines are superimposed to form the force-displacement curve of the overall connector. Figure 6 The dashed line in the middle shows a low stiffness region near the equilibrium position, and can even achieve near-zero stiffness, thereby effectively reducing the system's natural frequency and widening the vibration isolation frequency band.

[0036] By replacing the pre-compression adjustment pads 5 with those of different thicknesses, the initial compression of the rubber ball can be changed, causing the overall stiffness curve to shift on the displacement axis, thereby adjusting the dynamic stiffness near the equilibrium point. Figure 5 As shown in Figure a, the initial shape of the rubber ball is shown under different preload amounts. Figure 5 b represents the corresponding restoring force curve. Figure 6 As shown, the overall stiffness characteristics of the connector are under different preload adjustment amounts. It can be seen that when the preload is small, the stiffness approaches zero within the displacement range shown by the shaded area in the figure, achieving quasi-zero stiffness vibration isolation; when the preload is large, the overall stiffness is positive, which is suitable for occasions requiring higher stability.

[0037] The vibration damping effect of the connector was tested in simulation software. A simulated large load mass of 110kg was loaded on the upper part, and a 0~300Hz frequency sweep excitation was performed with an acceleration amplitude of 1mm. The acceleration transmissibility curves for different pad thicknesses were calculated and are shown in the figure. Figure 7 As shown, when the pad thickness is small, the natural frequency is the lowest and the vibration isolation bandwidth is the widest, making it suitable for general external excitation. Increasing the pad thickness results in stronger load-bearing capacity and higher stability, making it suitable for impact load scenarios or for avoiding structural resonance caused by specific low-frequency excitations such as corrugated road transport conditions or low-speed gear rotation. By selecting a suitable pad, vibration isolation performance can be optimized for different operating conditions.

[0038] As an alternative to the preload adjustment pad, an adjusting screw or electric adjustment device can be installed at the bottom of the base. Rotating the screw raises the support plate below the rubber ball, allowing for continuous adjustment of the initial compression. This method eliminates the need to replace the shims, but the structure is slightly more complex and is suitable for applications requiring online adjustment. In addition to two intersecting beams, three or four beams can be evenly distributed to improve load uniformity, but the structure of the upper connecting components needs corresponding adjustments. Regarding material replacement, the curved metal beams can be made of other elastic materials such as beryllium bronze or titanium alloy; the rubber ball can be made of polyurethane or nitrile rubber, ensuring that its elastic modulus and fatigue life meet requirements.

[0039] Through practical application experiments, the compact, adjustable stiffness, high-load vibration isolation connection structure of this invention, bearing a 26kg load on a single leg and subjected to vertical frequency sweep excitation of 2-20Hz and 2mm amplitude, was tested with 5mm, 6mm, and 7mm pads. The acceleration transmission curves obtained from the tests are shown below. Figure 8 As shown, when the pad thickness is 5mm, the initial vibration isolation frequency is as low as 3Hz, and the vibration isolation bandwidth is the widest, making it suitable for broadband vibration isolation. As the pad thickness increases and the preload of the sphere increases, the natural frequency of the connection structure shifts to higher frequencies, resulting in stronger load-bearing capacity and higher stability. By selecting a suitable pad and adjusting the preload value, the performance of the connection structure can be adjusted for different working conditions.

[0040] Compared with existing technologies, this invention significantly reduces the natural frequency: by combining the negative stiffness of the arc-shaped metal beam with the positive stiffness of the elastic rubber ball, and by using a preload adjustment pad to adjust the system to a near-zero stiffness operating point, the first-order natural frequency of the system can be reduced to 2.12Hz. This significant reduction in natural frequency directly broadens the low-frequency vibration isolation bandwidth. Secondly, the stiffness of this invention is continuously adjustable, adapting to multiple operating conditions: employing a purely mechanical preload adjustment, the system's natural frequency can be adjusted by changing the pad thickness, without altering structural dimensions or adding an external control unit. Compared to existing stiffness adjustment methods that require external power supply (such as magnetorheology or pneumatics) or disassembly and reassembly, this invention is particularly suitable for high-load conditions with complex excitation spectra.

[0041] The above-described specific implementations can be partially adjusted by those skilled in the art in different ways without departing from the principles and purpose of the present invention. The scope of protection of the present invention is defined by the claims and is not limited to the above-described specific implementations. All implementation schemes within the scope of the claims are bound by the present invention.

Claims

1. A compact, adjustable stiffness, high-load vibration isolation connection structure with beam-sphere cooperation, characterized in that, include: The pre-compression adjustment pad, elastic rubber ball, and arc-shaped metal beam assembly, as well as the upper connecting assembly connected to the arc-shaped metal beam assembly, are arranged sequentially from bottom to top within the base and housing. The upper end of the elastic rubber ball contacts the upper connecting assembly, and the lower end contacts the pre-compression adjustment pad. By replacing the pad with a pad of different thickness, the initial compression of the rubber ball can be changed, thereby adjusting the overall stiffness characteristics of the connector. When the base and the bottom of the housing are excited, the arc-shaped metal beam assembly bends and deforms and exhibits negative stiffness characteristics, while the elastic rubber ball exhibits positive stiffness characteristics and harmonizes them, so that the overall system exhibits low stiffness or near-zero stiffness, thereby effectively reducing the system's natural frequency and widening the vibration isolation frequency band. When external vertical vibration excitation is applied to the base, the curved metal beam undergoes bending deformation. The positive stiffness of the elastic rubber ball balances the negative stiffness of the metal beam, resulting in a low-stiffness region suitable for wide-frequency vibration isolation of heavy-load components. The elastic rubber ball generates gradually hardening positive stiffness under pressure. The combined effect of these two factors results in a low-stiffness region, or even near-zero stiffness, in the force-displacement curve of the overall connector near the equilibrium position, effectively reducing the system's natural frequency and broadening the vibration isolation bandwidth.

2. The compact, adjustable stiffness, high-load vibration isolation connection structure with beam-sphere cooperation according to claim 1, characterized in that, By replacing the preload adjustment pads with different thicknesses, the initial compression of the rubber ball can be changed, causing the overall stiffness curve to shift along the displacement axis, thereby adjusting the dynamic stiffness near the equilibrium point. When the preload is small, the stiffness approaches zero, achieving quasi-zero stiffness vibration isolation; when the preload is large, the overall stiffness is positive, suitable for applications requiring higher stability.

3. The compact, adjustable stiffness, high-load vibration isolation connection structure with beam-sphere cooperation according to claim 1 or 2, characterized in that, The upper connecting assembly includes: an upper assembly threaded plate, an upper assembly fixing plate, and an elastic ball pressure plate connected in sequence, wherein: the upper assembly threaded plate is bolted to the bottom of the large load component, the upper assembly fixing plate and the elastic ball pressure plate are connected by a cross fastener, and the lower end of the upper assembly fixing plate and the upper end of the elastic ball pressure plate together clamp the middle part of the arc-shaped metal beam.

4. The compact, adjustable stiffness, high-load vibration isolation connection structure with beam-sphere cooperation according to claim 3, characterized in that, The upper end of the elastic ball pressure plate is provided with a flat groove, and the lower end of the corresponding upper component fixing plate is provided with a flat groove and a cross fixing piece to achieve clamping of the arc-shaped metal beam.

5. The compact, adjustable stiffness, high-load vibration isolation connection structure with beam-sphere cooperation according to claim 1 or 2, characterized in that, The arc-shaped metal beam assembly includes two intersecting arc-shaped metal beams and four metal beam pressure plates respectively disposed at their ends, wherein the middle section of the arc-shaped metal beam is arc-shaped and is fixedly connected to the base and the outer shell through the metal beam pressure plates at both ends.

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