A three-degree-of-freedom decoupled quasi-zero stiffness low-frequency vibration isolator

Abstract

The application discloses a three-degree-of-freedom decoupled quasi-zero stiffness low-frequency vibration isolator, and belongs to the technical field of vibration control. The application is to solve the problems of high initial isolation frequency and incapability of adapting to multi-directional vibration isolation of traditional vibration isolators. The cross slide rail group and the four linear slide rail groups are fixed on the base through bolts and nuts, so that the sliding cross and the double-arc flexible beam combination can slide in the horizontal plane without overturning and rotating. The double-arc flexible beam combination is in a quasi-zero stiffness state by adjusting the slot holes to apply displacement constraints. The bottom of the sliding cross is connected with the double-arc flexible beam combination, four end portions are connected with the double-arc flexible beam, and the object platform is connected to the other end of the double-arc flexible beam. The object platform is finally connected to the vertical guide rod installed on the sliding cross through the linear bearing, so that three-degree-of-freedom displacement decoupling and multi-directional vibration isolation are realized. The application has the advantages of wide load adaptation range, flexible design, high space utilization rate, serializability and isolation of multiple-directional vibrations.

Description

TECHNICAL FIELD

[0001] The present application relates to a vibration isolator, in particular to a three-degree-of-freedom decoupled quasi-zero stiffness low-frequency vibration isolator, belonging to the technical field of vibration control. BACKGROUND

[0002] In recent years, the demand for low-frequency vibration isolation in the fields of precision instruments, medical equipment, aerospace, etc. is becoming higher and higher. The ordinary linear vibration isolator has high initial isolation frequency and poor isolation effect, so the quasi-zero stiffness vibration isolator with high static stiffness and low dynamic stiffness characteristics has become a new research hotspot. Quasi-zero stiffness can be realized by parallel connection of positive and negative stiffness or integrated flexible structure. The positive stiffness of the parallel connection structure of positive and negative stiffness can be provided by spring or electromagnetic, and the negative stiffness component can be provided by horizontal spring, buckling beam, electromagnetic and cam mechanism, etc. The integrated type directly obtains the quasi-zero stiffness characteristics by using closed geometry such as ellipse and circle, or through special design of flexible beam with spline curve and multi-arc.

[0003] There are many researches on vibration isolators that isolate vibration in a single direction in the prior art, typical examples of which are spring parallel structure and X-shaped link structure, such as documents “Zhao F, Ji J, Ye K, Luo Q, An innovative quasi-zero stiffness isolator with three pairs of oblique springs, Int. J. Mech. Sci. 2021; 192: 106093.” and “Yu C, Jiang Q, Fu Q, Yu K, Zhang J, Zhang N, The X-shaped structure with nonlinear positive stiffness compensation for low-frequency vibration isolation, Int. J. Mech. Sci. 2023; 259: 108598.”, etc.

[0004] Multi-directional vibration isolation is developed on the basis of single-directional vibration isolation. Existing researches are mainly in three forms of spatial parallel spring, X-shaped linkage and six-degree-of-freedom parallel Stewart platform, such as the documents “Sun X, Jing X, Multi-direction vibration isolation with quasi-zero stiffness by employing geometrical nonlinearity, Mech. Syst. Signal Proc. 2015; 62-63: 149-163.”, “Chai Y, Jing X, Guo Y, A compact X-shaped mechanism based 3-DOF anti-vibration unit with enhanced tunable QZS property, Mech. Syst. Signal Proc. 2022; 168: 108651.” and “Wang M, Hu Y, Sun Y, Ding J, Pu H, Yuan S, Zhao J, Peng Y, Xie S, Luo J, An Adjustable Low-Frequency Vibration Isolation Stewart Platform Based On Electromagnetic Negative Stiffness, Int. J. Mec. Sci. 2020; 181: 105714.”. However, in these researches, the responses of multiple linear degrees of freedom of the object to be isolated are coupled with each other, and when subjected to single-direction excitation, displacement responses, rotation and overturning will also occur in other degrees of freedom. SUMMARY

[0005] The purpose of the present application is to provide a three-degree-of-freedom decoupled quasi-zero stiffness low-frequency vibration isolator to solve the problem that the starting isolation frequency of the conventional vibration isolator is high and it cannot adapt to multi-directional vibration isolation.

[0006] A three-degree-of-freedom decoupled quasi-zero stiffness low-frequency vibration isolator comprises a base, an X-direction support frame, a Y-direction support frame, a horizontal fixed rod, a sliding cross, a double circular arc flexible beam, a load platform, a linear bearing, a vertical guide rod, an adjusting plate, a double circular arc flexible beam combination, a cross slide rail set and a linear slide rail set.

[0007] The cross slide rail group and the four linear slide rail groups are fixed on the base by bolts and nuts, the sliding cross and the flexible double-arc beam combination are assembled together by spline, the bottom of the sliding cross is connected with the cross slide rail group by bolts and nuts, the two opposite sides of the flexible double-arc beam combination are assembled with the X-direction support frame and the Y-direction support frame, the X-direction support frame and the Y-direction support frame are connected with the adjusting plates by bolts, the adjusting plates are fastened with the sliders of the linear slide rail groups by bolts, the horizontal fixing rods are inserted into the fixing holes of the X-direction support frame and the Y-direction support frame and locked by bolts, the bottom of the double-arc flexible beam is fixed on the four ends of the sliding cross by bolts, nuts and pressing plates, the upper part of the double-arc flexible beam is connected with the bearing platform by bolts and nuts, the vertical guide rod is installed on the sliding cross, the linear bearing is installed on the bearing platform and axially fixed by the spring retainer, and the vertical guide rod cooperates with the linear bearing.

[0008] Preferably, the double-arc flexible beam and the double-arc flexible beam combination are processed by 3D additive technology, and through holes for fixing are formed on the two sides, the double-arc flexible beam itself has quasi-zero stiffness characteristics, and the force-displacement curve is as shown in Figure 2 , and the size parameters are as shown in Figure 3 , including the radius R and the aspect ratio L of the circumscribed rectangle, the thickness D and the width W. h / L w The double-arc flexible beam can be designed according to formula (1).

[0009] (1)

[0010] Wherein, R0 is the selected radius, θ0 is the optimal central angle of the circular arc θ0 = 32.46°, and S is the length of the diagonal of the circumscribed rectangle.

[0011] Preferably, the quasi-zero stiffness vibration isolation unit in the horizontal direction is the double-arc flexible beam combination, the pre-compression displacement of the double-arc flexible beam combination is adjusted through the slot holes on the adjusting plate, the double-arc flexible beam is compressed to the static balance position, and the horizontal fixing rod makes the X-direction support frame and the Y-direction support frame keep synchronous during sliding.

[0012] Preferably, the quasi-zero stiffness vibration isolation unit in the vertical direction is the double-arc flexible beam, which is compressed to the static balance position by the vibration isolation load, and the vertical guide rod and the linear bearing ensure that the load platform does not rotate and overturn.

[0013] Preferably, the sliding cross connects the horizontal vibration isolation and the vertical vibration isolation together, so that the load platform has three-direction vibration isolation effect, and displacement decoupling is realized through the linear slide rail groups and the cross slide rail groups fixed on the base, as shown in Figure 4 When a single-direction vibration excitation is borne, only displacement response is generated in the excitation axis, and no response is generated in the other two axes.

[0014] Compared with the prior art, the present application has the following effects:

[0015] 1. A three-degree-of-freedom decoupled quasi-zero stiffness low-frequency vibration isolator realizes displacement decoupling among three degrees of freedom through a linear slide rail, so that the vibration isolation load only generates displacement response in the excited direction, compared with the prior art multi-direction vibration isolator, the quasi-zero stiffness characteristic reduces the initial isolation frequency, and the displacement decoupling enables the displacement response of the vibration isolation load to be decomposed into linear motion along the XYZ three axes, so that there is no rotation and overturning, and the vibration isolator has good vibration isolation effect when facing single direction or space excitation.

[0016] 2. The present application directly obtains quasi-zero stiffness by using a double-arc flexible beam processed by 3D additive technology and a double-arc flexible beam combination, compared with a parallel quasi-zero stiffness structure, the double-arc flexible beam combination is more compact, the double-arc flexible beam structure is simple and easy to design, and the structure parameters can be customized according to the load demand, and the number of beams can be selected as needed, so that the vibration isolator has the advantages of high space utilization, flexible design and serializability.

[0017] 3. The present application proposes to use displacement constraint in the horizontal direction to make the double-arc flexible beam combination reach the quasi-zero stiffness interval, compared with the way of reaching the static balance position by mass loading, the range of the optimal load mass is larger, and the flexible beam will not be damaged by a large load mass, the structure parameters of the double-arc flexible beam in the horizontal direction and the vertical direction can be adjusted simultaneously to adapt to the change of the load demand for customized design and optimal load matching, so that the vibration isolator has the advantage of strong load change adaptability. BRIEF DESCRIPTION OF DRAWINGS

[0018] Figure 1 It is a structure schematic diagram of a three-degree-of-freedom decoupled quasi-zero stiffness low-frequency vibration isolator.

[0019] Figure 2 It is a force-displacement curve of a double-arc flexible beam.

[0020] Figure 3 It is a structure parameter of a double-arc flexible beam.

[0021] Figure 4 It is a schematic diagram of displacement decoupling principle.

[0022] Figure 5 It is a cross slide rail structure schematic diagram.

[0023] Figure 6 It is a linear slide rail structure schematic diagram.

[0024] Figure 7 It is an explosion schematic diagram of a horizontal direction vibration isolation structure.

[0025] Figure 8 It is a vertical direction vibration isolation structure schematic diagram.

[0026] In the diagram: 1—Base, 2—X-direction support frame, 3—Y-direction support frame, 4—Horizontal fixed rod, 5—Sliding cross, 6—Double arc flexible beam, 7—Loading platform, 8—Linear bearing, 9—Vertical guide rod, 10—Adjusting plate, 11—Double arc flexible beam assembly, 12—Cross slide rail assembly, 13—Linear slide rail assembly, 14—Pressure plate, 15—Locking hole, 16—Allowing hole, 17—Adjusting slot, 18—Fixing slot, 19—Linear slide rail, 20—Slider, 21—Lower fixed block, 22—Upper fixed block, 23—Bottom spline, 24—Spline groove, 25—Slide rail fixing support, 26—Fixing hole, 27—Mounting slot. Detailed Implementation

[0027] Preferred embodiments of the present invention will now be described in detail with reference to the accompanying drawings.

[0028] like Figures 4 to 8 As shown, the three-degree-of-freedom decoupled quasi-zero stiffness low-frequency vibration isolator of the present invention includes a base 1, an X-direction support frame 2, a Y-direction support frame 3, a horizontal fixed rod 4, a sliding cross 5, a double circular arc flexible beam 6, a loading platform 7, a linear bearing 8, a vertical guide rod 9, an adjustment plate 10, a double circular arc flexible beam assembly 11, a cross slide rail assembly 12, a linear slide rail assembly 13, a pressure plate 14, a locking hole 15, a clearance hole 16, an adjustment slot hole 17, a fixing slot hole 18, a bottom spline 23, a spline groove 24, a slide rail fixing support 25, a fixing hole 26, and a mounting slot hole 27.

[0029] The cross slide rail assembly 12 includes a linear slide rail 19, a slider 20, a lower fixed block 21, and an upper fixed block 22. The lower fixed block 21 and the upper fixed block 22 are each connected to a slider 20 by bolts. The sliding directions of the two sliders 20 are perpendicular to each other. Then, the upper fixed block 21 and the lower fixed block 22 are connected together with bolts and nuts, and the linear slide rail 19 slides into the upper and lower sliders 20.

[0030] Further: Four sets of linear slide rails 13 are connected circumferentially along the base 1 by bolts and nuts.

[0031] Further: The sliding cross 5 and the double arc flexible beam assembly 11 are assembled together by the spline 23 at the bottom of the sliding cross 5 and the spline groove 24 at the center of the double arc flexible beam assembly 11. The upper slide rail of the cross slide rail assembly 12 is connected to the slide rail fixing support 25 of the sliding cross 5 by bolts and nuts.

[0032] Further: The four rectangular fixing blocks of the double arc flexible beam 11 are pressed into the grooves at the bottom of the X-direction support frame 2 and the Y-direction support frame 3 respectively. The four horizontal fixing rods 4 are inserted into the fixing holes 26 of the two X-direction support frames 2 and the two Y-direction support frames 3 respectively through the clearance holes 16 of the sliding cross 5, and locked with bolts and nuts.

[0033] Further: four adjustment plates 10 are bolted to the corresponding sliding blocks of the linear slide rail group 13 respectively, the bolt passes through the adjustment slot hole 17 on the X-direction support frame 2 and the Y-direction support frame 3, the fixed slot hole 18 on the adjustment plate 10, and is tightened with a nut, completing the assembly of the horizontal direction vibration isolation structure.

[0034] Further: the vertical guide rod 10 is inserted into the mounting slot hole 27 of the sliding cross 5, the bolt passes through the locking hole 15 of the sliding cross 5 and is locked with a nut, and the pressing plate 14 and the double-arc flexible beam 6 are fixed to the four top ends of the sliding cross 5 with a bolt and a nut.

[0035] Further: the linear bearing 8 is inserted into the through hole of the object platform 7 and is axially fixed with a spring retainer, the vertical guide rod is inserted through the linear bearing 8 to complete the assembly, and the pressing plate 14 and the double-arc flexible beam 6 are fixed to the corresponding mounting supports of the object platform 7 with a bolt and a nut.

[0036] The relative position relationship between the X-direction support frame 2 and the Y-direction support frame 3 and the adjustment plate 10 can be changed through the adjustment slot hole 17 and the fixed slot hole 18, so as to realize the adjustment of the pre-compression displacement of the double-arc flexible beam combination 11.

[0037] The cross slide rail group 12 bears the gravity of the entire load, so that the sliding cross keeps sliding only in the horizontal plane and does not rotate or overturn around any axis, and the linear slide rail group 13 does not bear the load and only maintains the sliding of the double-arc flexible beam combination in the horizontal plane, without rotating or overturning around any axis.

[0038] The embodiment is only an exemplary description of the patent and does not limit the protection scope thereof, and any modification and change can be made by those skilled in the art in the form and details of implementation, but the protection scope of the present application must be limited within the range defined by the appended claims.

Claims

1. A three-degree-of-freedom decoupled quasi-zero stiffness low frequency vibration isolator characterized by: The base (1), X-direction support frame (2), Y-direction support frame (3), horizontal fixed rod (4), sliding cross (5), double circular arc flexible beam (6), object carrying platform (7), linear bearing (8), vertical guide rod (9), adjusting plate (10), double circular arc flexible beam combination (11), cross slide rail group (12), linear slide rail group (13), pressing plate (14), locking hole (15), avoiding hole (16), adjusting slot hole (17), fixed slot hole (18), bottom spline (23), spline groove (24), slide rail fixed support (25), fixed hole (26), mounting slot hole (27); The cross slide rail group (12) includes a linear slide rail (19), a sliding block (20), a lower fixed block (21), and an upper fixed block (22). The lower fixed block (21) and the upper fixed block (22) are connected with a sliding block (20) through a bolt, respectively. The sliding direction of the two sliding blocks (20) is perpendicular to each other. Then, the lower fixed block (21) and the upper fixed block (22) are connected together through a bolt and a nut. The linear slide rail (19) slides into the upper and lower sliding blocks (20); The base (1) is connected with four groups of linear slide rail groups (13) through a bolt and a nut along the circumference. The sliding cross (5) and the double circular arc flexible beam combination (11) are assembled together through the spline (23) at the bottom of the sliding cross (5) and the spline groove (24) at the center of the double circular arc flexible beam combination (11). The upper rail of the cross slide rail group (12) is connected to the slide rail fixed support (25) of the sliding cross (5) through a bolt and a nut. The four rectangular fixed blocks of the double circular arc flexible beam combination (11) are pressed into the recesses at the bottom of the X-direction support frame (2) and the Y-direction support frame (3), respectively. Four horizontal fixed rods (4) pass through the avoiding holes (16) of the sliding cross (5) and are inserted into the fixed holes (26) of the two X-direction support frames (2) and the two Y-direction support frames (3), respectively, and are locked with a bolt and a nut. Four adjusting plates (10) are connected to the corresponding sliding blocks of the linear slide rail groups (13) through a bolt, respectively. The bolt passes through the adjusting slot holes (17) on the X-direction support frame (2) and the Y-direction support frame (3) and the fixed slot holes (18) on the adjusting plate (10) and is tightened with a nut. The assembly of the horizontal direction vibration isolation structure is completed.

2. A three-degree-of-freedom decoupled quasi-zero stiffness low frequency vibration isolator according to claim 1, characterized in that: The vertical guide rod (9) is inserted into the mounting slot hole (27) of the sliding cross (5). The bolt passes through the locking hole (15) of the sliding cross (5) and is locked with a nut. The pressing plate (14) and the double circular arc flexible beam (6) are fixed to the four top ends of the sliding cross (5) through a bolt and a nut. The linear bearing (8) is inserted into the through hole of the object carrying platform (7) and is axially fixed with a spring retainer. The vertical guide rod is inserted into the linear bearing (8) to complete the assembly. The pressing plate (14) and the double circular arc flexible beam (6) are fixed to the corresponding mounting supports of the object carrying platform (7) through a bolt and a nut.

3. The three-degree-of-freedom decoupled quasi-zero stiffness low-frequency vibration isolator according to claim 1, characterized in that: The adjusting slot hole (17) and the fixing slot hole (18) can change the relative position relationship between the X-direction support frame (2), the Y-direction support frame (3) and the adjusting plate (10), so as to realize the adjustment of the pre-compression displacement of the double-circular-arc flexible beam combination (11); the cross slide rail group (12) bears the gravity of the entire load, so that the sliding cross (5) only keeps sliding in the horizontal plane and does not rotate or overturn around any axis; the linear slide rail group (13) does not bear the load and only maintains the sliding of the double-circular-arc flexible beam combination (11) in the horizontal plane, and does not rotate or overturn around any axis.

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