Quasi-zero stiffness shock isolation device based on hydraulic negative stiffness and design method thereof

Abstract

The invention relates to the technical field of structural engineering shock isolation, in particular to a quasi-zero stiffness shock isolation device based on hydraulic negative stiffness and a design method thereof. A quasi-zero stiffness shock isolation device based on hydraulic negative stiffness comprises a vertical bearing unit which comprises at least one vertical spring, and the two ends of the vertical spring are connected to the top face of a lower connecting plate and the bottom face of an upper connecting plate respectively; the negative stiffness unit comprises a hydraulic oil cylinder and a piston rod, the piston rod extends into the hydraulic oil cylinder, and the hydraulic oil cylinder and the piston rod are hinged to the lower connecting plate and the upper connecting plate respectively, or the hydraulic oil cylinder and the piston rod are hinged to the upper connecting plate and the lower connecting plate respectively; the distance between the upper connecting plate and the lower connecting plate is increased or decreased to drive the length of the piston rod extending into the hydraulic oil cylinder to change so as to provide negative stiffness. The problems that in the prior art, when a nonlinear vibration isolation system provides negative stiffness in a metal horizontal spring compensation mode, a quasi-zero stiffness working zone is narrow, the bearing capacity is low, and the requirement for installation precision is high are solved.

Description

Technical Field

[0001] This invention relates to the technical field of seismic isolation in structural engineering, and particularly to a quasi-zero stiffness seismic isolation device based on hydraulic negative stiffness and its design method. Background Technology

[0002] Traditional horizontal seismic isolation bearings (such as laminated rubber bearings) extend the horizontal period of a structure through horizontal shear deformation, but their vertical stiffness is much higher than their horizontal stiffness (usually 100 to 1000 times the horizontal stiffness), causing vertical seismic energy to be directly transferred to the superstructure. Especially in near-field earthquakes, the amplitude of the vertical seismic component may exceed that of the horizontal component, exacerbating the risk of damage to cantilevered, long-span, and other structures and equipment.

[0003] Currently, most three-dimensional bearings adopt a series structure of "horizontal isolation layer + vertical isolation layer" (such as lead core rubber bearing + disc spring), but they often have problems such as horizontal-vertical coupling, high vertical load-bearing capacity and low stiffness coordination, complex structure and durability.

[0004] Nonlinear vibration isolation systems can effectively overcome the challenge of balancing high load-bearing capacity and low stiffness in traditional linear systems. However, existing technologies use horizontal metal springs or vertical metal disc springs to provide negative stiffness. Horizontal compensation methods often require a total stiffness ratio of 3 to 5 times or higher between the horizontal and vertical springs. For building structures and bridges, vertical load-bearing capacity requirements are often very high. For example, for a 5000kN bearing, the total stiffness of the horizontal springs often needs to reach around 500-1000kN / mm, which typically presents technical challenges such as extremely high stress at the connection points, significant manufacturing difficulties, poor performance stability, and assembly difficulties. Vertical compensation methods generally only provide negative stiffness within a very small range (usually a few millimeters) near the inflection point of spring deformation. This causes the vertical stiffness of the bearing to increase rapidly during large vertical deformation, leading to a deterioration in the vibration isolation effect. Summary of the Invention

[0005] The purpose of this invention is to overcome the problems of narrow quasi-zero stiffness working zone, low load-bearing capacity, and high installation accuracy requirements when providing negative stiffness through metal horizontal spring compensation in existing nonlinear vibration isolation systems, and to provide a quasi-zero stiffness vibration isolation device based on hydraulic negative stiffness and its design method.

[0006] In a first aspect, the present invention provides a quasi-zero stiffness vibration isolation device based on hydraulic negative stiffness, comprising: A vertical support unit includes at least one vertical spring, with its two ends connected to the top surface of the lower connecting plate and the bottom surface of the upper connecting plate, respectively. The negative stiffness unit includes a hydraulic cylinder and a piston rod, the piston rod extending into the hydraulic cylinder. The hydraulic cylinder and the piston rod are respectively hinged to the lower connecting plate and the upper connecting plate, or the hydraulic cylinder and the piston rod are respectively hinged to the upper connecting plate and the lower connecting plate. Increasing or decreasing the distance between the upper connecting plate and the lower connecting plate can cause the length of the piston rod extending into the hydraulic cylinder to decrease or increase, thereby providing negative stiffness.

[0007] The number of vertical springs, telescopic devices, and displacement coupling devices are determined based on the actual situation. A hydraulic cylinder can be equipped with a single piston rod or at least two piston rods, depending on the specific circumstances.

[0008] The increase or decrease in the distance between the upper and lower connecting plates causes the vertical spring to lengthen or shorten, thus providing positive stiffness. The negative stiffness unit includes a hydraulic cylinder and a piston rod. When the distance between the upper and lower connecting plates changes, the length of the piston rod extending into the hydraulic cylinder changes. The hydraulic cylinder, through the piston rod, provides a force in the vertical direction that is opposite to the change in vertical spring force, thereby achieving negative stiffness compensation. The axial displacement of the hydraulic cylinder is much smaller than the vertical displacement, resulting in greater vertical displacement compensation and better addressing the problem of narrow near-zero stiffness working zones. Furthermore, the pressure of the hydraulic cylinder can be adjusted via an accumulator to match different vertical load-bearing units. Compared to existing technologies that use springs, this eliminates the need for separate designs when multiple supports are present, reducing workload. Moreover, the hydraulic cylinder allows adjustment of the accumulator's state during installation, facilitating installation.

[0009] Preferably, it further includes an upper connecting plate and a lower connecting plate, the upper connecting plate being connected to the upper support, the lower connecting plate being connected to the lower support, and the two ends of the vertical spring being connected to the upper connecting plate and the lower connecting plate respectively.

[0010] With an upper connecting plate and a lower connecting plate, and the two ends of the vertical spring connected to the upper connecting plate and the lower connecting plate respectively, when there is more than one vertical spring, the upper connecting plate and the lower connecting plate can drive several vertical springs to move in coordination.

[0011] Preferably, the upper connecting plate is provided with a lower extension, the lower connecting plate is provided with an upper extension, the lower extension surrounds the upper extension, or the upper extension surrounds the lower extension.

[0012] The lower extension faces the lower connecting plate, and the upper extension faces the upper connecting plate, which limits the minimum distance between the upper and lower connecting plates. The lower extension surrounds the upper extension, or the upper extension encloses the lower extension, to minimize the offset between the upper and lower connecting plates and improve the structural stability of the device.

[0013] Preferably, the hydraulic cylinder and the piston rod are connected to the upper connecting plate and the lower connecting plate through the lower extension and the upper extension, respectively. When both the upper connecting plate and the lower connecting plate are in their initial positions, the piston rod extends the shortest length out of the hydraulic cylinder.

[0014] The initial positions of the upper and lower connecting plates are determined when the distance between the upper and lower supports is the initial spacing. When both the upper and lower connecting plates are in their initial positions, the piston rod extends the shortest length out of the hydraulic cylinder. Therefore, when the distance between the upper and lower connecting plates changes, the piston rod extends the longer length out of the hydraulic cylinder, thus providing negative stiffness.

[0015] Preferably, both the lower extension and the upper extension are provided with ear plates, and the hydraulic cylinder and the piston rod are both connected to the ear plates.

[0016] Preferably, the vertical spring is a helical spring, a ring spring, or a hydraulic spring.

[0017] Preferably, the vertical support unit further includes a guide rod, which is disposed inside the vertical spring.

[0018] The guide rod is installed to minimize bending of the vertical spring axis, thus ensuring the structural stability of the device.

[0019] Preferably, the vertical support unit includes a plurality of vertical springs spaced apart, with adjacent vertical springs wound in opposite directions.

[0020] The spacing of multiple vertical springs helps to minimize stress concentration. The opposite winding directions of adjacent vertical springs ensure torque balance, thus improving the stability of the device.

[0021] Preferably, the hydraulic cylinder is a double-rod symmetrical cylinder or a single-piston rod cylinder.

[0022] In a second aspect, the present invention provides a design method for a quasi-zero stiffness vibration isolation device based on hydraulic negative stiffness, used to design a quasi-zero stiffness vibration isolation device based on hydraulic negative stiffness as described above, comprising the following steps: S1. Based on the vertical load transmitted by the upper support pier. F and the pre-compression of the vertical spring h 0. Determine the total vertical stiffness of the vertical bearing element. ; S2, according to Vertical displacement of the lower support pier Determine the vertical component of the hydraulic cylinder under the condition of near-zero vertical stiffness. ; S3. Based on the accumulator pressure of the hydraulic cylinder P 1 and the working area of ​​the hydraulic cylinder A Determine the actual thrust of the hydraulic cylinder ; S4, according to , and h 0 Confirmed F and The relational expression is used to complete the design of a seismic isolation system with quasi-zero vertical stiffness.

[0023] This design method first determines the total vertical stiffness of the vertical bearing unit based on the external forces, then determines the vertical component of the hydraulic cylinder under quasi-zero vertical stiffness, and finally corrects the actual thrust of the hydraulic cylinder. Expressions are then established for the vertical load transmitted by the upper support and the vertical displacement of the lower support, thus completing the design of a seismic isolation system with quasi-zero vertical stiffness characteristics. This invention overcomes the shortcomings of existing quasi-zero stiffness devices, which mostly achieve quasi-zero stiffness through parallel connections of ring springs and disc springs or helical springs and disc springs. However, the negative stiffness provided by disc springs has a small and unstable compression region, resulting in poor seismic isolation performance.

[0024] Compared with the prior art, the beneficial effects of the present invention are as follows: 1. This invention provides a quasi-zero stiffness vibration isolation device based on hydraulic negative stiffness, comprising a vertical bearing unit and a negative stiffness unit. The vertical bearing unit includes at least one vertical spring, with its ends connected to the top surface of the lower connecting plate and the bottom surface of the upper connecting plate, respectively. The negative stiffness unit includes a hydraulic cylinder and a piston rod. When the distance between the upper support and the lower support changes, the length of the piston rod extending into the hydraulic cylinder changes, and the hydraulic cylinder provides power to the piston rod in the same direction, thereby providing negative stiffness. The axial displacement of the hydraulic cylinder is much smaller than the vertical displacement, resulting in greater compensation for vertical displacement and better addressing the problem of a narrow quasi-zero stiffness working zone. Furthermore, the pressure of the hydraulic cylinder can be adjusted via an accumulator to match different vertical bearing units. Compared to existing technologies that use springs, this eliminates the need for separate design when there are multiple supports, reducing workload. Moreover, the hydraulic cylinder allows adjustment of the accumulator's state during installation, facilitating installation. This device overcomes the shortcomings of existing nonlinear vibration isolation systems that provide negative stiffness through metal horizontal spring compensation, such as narrow quasi-zero stiffness working zone, low load-bearing capacity, and high installation accuracy requirements.

[0025] 2. This invention provides a design method for a quasi-zero stiffness seismic isolation device based on hydraulic negative stiffness. First, the total vertical stiffness of the vertical bearing unit is determined according to the external force. Then, the vertical component force of the hydraulic cylinder is determined under the condition of quasi-zero vertical stiffness. After that, the actual thrust of the hydraulic cylinder is corrected, and expressions for the vertical load transmitted by the upper support and the vertical displacement of the lower support are established to complete the design of a seismic isolation system with quasi-zero vertical stiffness characteristics. Attached Figure Description

[0026] Figure 1 This is a front view of a quasi-zero stiffness vibration isolation device based on hydraulic negative stiffness according to the present invention. Figure 1 ; Figure 2 This is a front view of a quasi-zero stiffness vibration isolation device based on hydraulic negative stiffness according to the present invention. Figure 2 ; Figure 3 This is a front view of a quasi-zero stiffness vibration isolation device based on hydraulic negative stiffness according to the present invention. Figure 3 ; Figure 4 This is a schematic diagram of parameters for a design method of a quasi-zero stiffness vibration isolation device based on hydraulic negative stiffness according to the present invention. Figure 5 This is a curve showing the relationship between the vertical load transmitted by the upper support and the displacement of the lower support when the lower support moves up and down according to the present invention. icon: 1-Upper connecting plate, 101-Lower extension, 2-Lower connecting plate, 201-Upper extension, 3-Vertical spring, 4-Guide rod, 5-Hydraulic cylinder, 6-Piston rod, 7-Ear plate. Detailed Implementation

[0027] The present invention will now be described in further detail with reference to specific embodiments. However, this should not be construed as limiting the scope of the present invention to the following embodiments; all technologies implemented based on the content of the present invention fall within the scope of the present invention.

[0028] Unless otherwise specified, the use of terms such as "upper," "lower," "left," "right," "center," "inner," and "outer" to indicate orientation or positional relationships in the description of specific embodiments of the present invention is based on the orientation or positional relationships shown in the accompanying drawings, or the orientation or positional relationship in which the product / equipment / device is typically placed during use. These terms are merely for the purpose of facilitating the description of the present invention or simplifying the description in specific embodiments, enabling those skilled in the art to quickly understand the solution, and do not indicate or imply that a particular device / component / element must have a specific orientation, or be constructed and operated in a specific positional relationship. Therefore, they should not be construed as limitations on the present invention.

[0029] Furthermore, the use of terms such as "horizontal," "vertical," "suspended," and "parallel" does not imply that the corresponding device / component / element must be absolutely horizontal, vertical, suspended, or parallel, but rather that it can be slightly tilted or have a deviation. For example, "horizontal" merely means that its direction is more horizontal relative to "vertical," not that the structure must be completely horizontal, but that it can be slightly tilted. Alternatively, it can be simplified to mean that the corresponding device / component / element, when set in a "horizontal," "vertical," "suspended," or "parallel" direction, can have an error / deviation of ±10% relative to the corresponding direction, more preferably within ±8%, more preferably within ±6%, more preferably within ±5%, and more preferably within ±4%. As long as the corresponding device / component / element is within the error / deviation range, it can still achieve its function in the present invention.

[0030] Furthermore, the use of terms such as "first," "second," and "third" in terminology is merely for distinguishing descriptions of identical or similar components and should not be interpreted as emphasizing or implying the relative importance of a particular component.

[0031] Furthermore, in the description of the embodiments of the present invention, "several", "more than", and "a number of" represent at least two. The number can be any number, such as 2, 3, 4, 5, 6, 7, 8, or 9, and can even exceed nine.

[0032] Furthermore, in the description of the technical solution of this invention, unless otherwise explicitly specified / limited / restricted, the terms "set up," "install," "connect," "link," "provided with," "laid out," and "arranged" should be interpreted broadly. For example, they can refer to fixed connections, detachable connections, or integral connections; they can refer to common connection methods in the art, such as welding, riveting, bolting, and threaded connections. Such connections can be mechanical, electrical, or communication connections; they can be direct connections or indirect connections through an intermediate medium; and they can refer to the internal communication between two components.

[0033] Example 1 like Figures 1 to 3 As shown, a quasi-zero stiffness vibration isolation device based on hydraulic negative stiffness includes: The vertical support unit includes at least one vertical spring 3, with both ends of the vertical spring 3 connected to the top surface of the lower connecting plate and the bottom surface of the upper connecting plate, respectively. The negative stiffness unit includes a hydraulic cylinder 5 and a piston rod 6. The piston rod 6 extends into the hydraulic cylinder 5. The hydraulic cylinder 5 and the piston rod 6 are respectively hinged to the lower connecting plate 2 and the upper connecting plate 1, or the hydraulic cylinder 5 and the piston rod 6 are respectively hinged to the upper connecting plate 1 and the lower connecting plate 2. Increasing or decreasing the distance between the upper connecting plate 1 and the lower connecting plate 2 can cause the length of the piston rod 6 extending into the hydraulic cylinder 5 to decrease or increase, thereby providing negative stiffness.

[0034] The number of vertical springs 3, the number of telescopic devices, and the number of displacement coupling devices are determined according to the actual situation. A hydraulic cylinder 5 can be equipped with a single piston rod 6 or at least two piston rods 6, depending on the actual situation.

[0035] The increase or decrease in the distance between the upper connecting plate 1 and the lower connecting plate 2 causes the vertical spring 3 to lengthen or shorten, thus providing positive stiffness. The negative stiffness unit includes a hydraulic cylinder 5 and a piston rod 6. When the distance between the upper connecting plate 1 and the lower connecting plate 2 changes, the length by which the piston rod 6 extends into the hydraulic cylinder 5 changes. The hydraulic cylinder 5 provides power to the piston rod 6 in the same direction, thus providing negative stiffness. The axial displacement of the hydraulic cylinder 5 is much smaller than the vertical displacement, resulting in greater compensation for vertical displacement and better addressing the problem of narrow, near-zero stiffness working zones. Furthermore, the pressure of the hydraulic cylinder 5 can be adjusted via an accumulator to match different vertical load-bearing units. Compared to existing technologies that use springs, this eliminates the need for separate designs when there are multiple supports, reducing workload. Moreover, the hydraulic cylinder 5 allows adjustment of the accumulator's state during installation, facilitating installation.

[0036] Furthermore, it also includes an upper connecting plate 1 and a lower connecting plate 2, wherein the upper connecting plate 1 is connected to the upper support, the lower connecting plate 2 is connected to the lower support, and the two ends of the vertical spring 3 are respectively connected to the upper connecting plate 1 and the lower connecting plate 2.

[0037] With an upper connecting plate 1 and a lower connecting plate 2, and the two ends of the vertical spring 3 connected to the upper connecting plate 1 and the lower connecting plate 2 respectively, when there is more than one vertical spring 3, the upper connecting plate 1 and the lower connecting plate 2 can drive several vertical springs 3 to move in coordination.

[0038] Furthermore, the upper connecting plate 1 is provided with a lower extension 101, and the lower connecting plate 2 is provided with an upper extension 201. The lower extension 101 surrounds the upper extension 201, or the upper extension 201 surrounds the lower extension 101.

[0039] The lower extension 101 faces the lower connecting plate 2, and the upper extension 201 faces the upper connecting plate 1, which can limit the minimum distance between the upper connecting plate 1 and the lower connecting plate 2. The lower extension 101 surrounds the upper extension 201, or the upper extension 201 encloses the lower extension 101, so as to avoid the upper connecting plate 1 and the lower connecting plate 2 from shifting as much as possible, which helps to improve the structural stability of the device.

[0040] Furthermore, the hydraulic cylinder 5 and the piston rod 6 are connected to the upper connecting plate 1 and the lower connecting plate 2 via the lower extension 101 and the upper extension 201. When both the upper connecting plate 1 and the lower connecting plate 2 are in their initial positions, the piston rod 6 extends the shortest length beyond the hydraulic cylinder 5.

[0041] The initial positions of the upper connecting plate 1 and the lower connecting plate 2 are determined when the distance between the upper and lower supports is the initial spacing. When both the upper connecting plate 1 and the lower connecting plate 2 are in their initial positions, the piston rod 6 extends the shortest length out of the hydraulic cylinder 5. Therefore, when the distance between the upper connecting plate 1 and the lower connecting plate 2 changes, the length of the piston rod 6 extending out of the hydraulic cylinder 5 increases, thereby providing negative stiffness.

[0042] Furthermore, both the lower extension 101 and the upper extension 201 are provided with ear plates 7, and the hydraulic cylinder 5 and the piston rod 6 are both connected to the ear plates 7.

[0043] Furthermore, the vertical spring 3 is a helical spring, a ring spring, or a hydraulic spring.

[0044] Furthermore, the vertical support unit also includes a guide rod 4, which is disposed inside the vertical spring 3.

[0045] The guide rod 4 is installed to avoid bending of the axis of the vertical spring 3 as much as possible, which helps to ensure the structural stability of the device.

[0046] Furthermore, the vertical support unit includes a plurality of vertical springs 3 spaced apart, with adjacent vertical springs 3 winding in opposite directions.

[0047] Multiple vertical springs 3 are spaced apart to minimize stress concentration. Adjacent vertical springs 3 have opposite winding directions to ensure torque balance, thus improving the stability of the device.

[0048] Furthermore, the hydraulic cylinder 5 is a double-rod symmetrical cylinder or a single-piston rod cylinder.

[0049] The present embodiment has the following beneficial effects: 1. The axial displacement of the hydraulic cylinder is much smaller than the vertical displacement, and the vertical displacement compensation is larger, which can meet the negative stiffness range of at least ±30mm and solve the problem of narrow quasi-zero stiffness working zone. 2. It avoids the problem of achieving a high stiffness ratio using traditional metal springs, which require different dimensions to be designed according to different load-bearing requirements. If the building is large and has many structural columns, each support needs to be designed individually, resulting in a very large workload. In contrast, the pressure of the hydraulic cylinder 5 can be adjusted through an accumulator to match different vertical load-bearing units, eliminating the need for repetitive design and greatly reducing the workload. 3. During installation, the accumulator has not yet been filled with oil and pressurized, and the piston rod 6 is in a free-floating state, making it easy to adjust and align. In addition, each component can be produced in a modular manner, making construction and installation relatively convenient.

[0050] Example 2 like Figures 4 to 5 As shown, a design method for a quasi-zero stiffness vibration isolation device based on hydraulic negative stiffness is used to design a quasi-zero stiffness vibration isolation device based on hydraulic negative stiffness as described in Example 1, comprising the following steps: S1, Vertical load transmitted by the upper support pier F and the pre-compression of vertical spring 3 h 0. Determine the total vertical stiffness of the vertical bearing element. ; S2, according to Vertical displacement of the lower support pier Determine the vertical component of the hydraulic cylinder 5 under the condition of near-zero vertical stiffness. ; S3. Based on the accumulator pressure of the hydraulic cylinder 5 P The working area of ​​1 and the hydraulic cylinder 5 A Determine the actual thrust of the hydraulic cylinder 5 ; S4, according to , and h 0 Confirmed F and The relational expression is used to complete the design of a seismic isolation system with quasi-zero vertical stiffness.

[0051] This design method first determines the total vertical stiffness of the vertical bearing unit based on the external forces, then determines the vertical component force of the hydraulic cylinder 5 under the condition of quasi-zero vertical stiffness, then corrects the actual thrust of the hydraulic cylinder 5, and establishes expressions for the vertical force on the upper connecting plate 1 and the vertical displacement of the lower support, thus completing the design of a seismic isolation system with quasi-zero vertical stiffness characteristics. This invention overcomes the shortcomings of existing quasi-zero stiffness devices, which mostly achieve quasi-zero stiffness through parallel connections of ring springs and disc springs or helical springs and disc springs. However, the compression area provided by disc springs for negative stiffness is small and unstable, resulting in poor seismic isolation performance.

[0052] The following is the complete calculation formula, including the formula itself: Step 1: The total stiffness of the vertical bearing unit is based on the pre-compression of the vertical spring 3. h 0. Vertical load transmitted by the upper support pier F Determined by formula (1); (1) in, K i For the stiffness of a single vertical load-bearing unit, h 0 represents the pre-compression amount of the vertical bearing unit. F This is the reaction force at the bottom of the superstructure columns; Step 2: To achieve quasi-zero vertical stiffness, the vertical component of the thrust of hydraulic cylinder 5 must satisfy formulas (2) to (3); (2) (3) in, F i The thrust of a single hydraulic cylinder 5; F iy For a single hydraulic cylinder, there are 5 vertical force components; L 0 represents the initial installation length of hydraulic cylinder 5; h This represents the vertical displacement of the lower support pier. The above calculations only preliminarily determine the thrust of hydraulic cylinder 5. Further determination of the structural parameters and pressure rating of hydraulic cylinder 5 is needed. The pressure of hydraulic cylinder 5 is adjusted by accumulator boosting and can be corrected based on detailed calculation data to minimize compensation errors. Step 3: The actual thrust of hydraulic cylinder 5 is determined by formulas (4) and (5); (4) (5) in, P 1 represents the accumulator pressure; A The working area of ​​hydraulic cylinder 5; D The piston rod has a diameter of 6. Step 4: The accumulator pressure is determined using formulas (6) to (9); (6) (7) (8) (9) (10) (11) in, P 1 represents the accumulator pressure; P 2 represents the accumulator's oil filling pressure; V 1 represents the volume of the accumulator after it is filled with oil; V 2 represents the volume of the accumulator airbag; V 0 represents the rated volume of the airbag; P 3 represents the airbag pre-inflation pressure; ΔV This represents the change in cylinder volume; n This refers to the number of hydraulic cylinders 5; L 1 represents the straight-line distance between the hydraulic cylinder hinge point and the hydraulic cylinder hinge point.

[0053] Step 5: The relationship between the vertical resultant force on the connecting plate 1 on the support and the compressive deformation of the support is determined by formula (12); (12) In practical use, the specific calculation process is as follows: (1) Set the vertical load transmitted from the upper support pier to be 2000kN, the design stroke of the vertical bearing unit to be ±30mm, and the pre-compression amount h0 to be 100mm. Then the total vertical stiffness should not exceed 2000 / 100=20kN / mm. (2) The initial installation length of hydraulic cylinder 5 is initially determined to be 150mm. At the initial position (vertical displacement of support Δh=0), the total thrust of hydraulic cylinder 5 is 20×(1502+02)1 / 2=3000kN. Assuming that a total of four hydraulic cylinders 5 are configured, the maximum thrust of a single hydraulic cylinder 5 is 750kN. (3) The diameter of piston rod 6 is initially determined to be 218mm. Then the working area of ​​hydraulic cylinder 5 is A=3.14×2182 / 4=37325.3mm2; accumulator pressure P1=750×103 / 37325.3=20MPa=P2, that is, the accumulator charging pressure at the initial position P2=20MPa; (4) Taking the rated volume of the airbag as 10L, when the lower connecting plate 2 deforms vertically by Δh, the straight-line distance of the hinge point of the hydraulic cylinder 5 is L1 = (1502 + Δh2)1 / 2; the volume of the accumulator after filling with oil is V1 = 0.75 × 10 = 7.5L; the change in cylinder volume is ΔV = (L1 - 150) × 37325.3 = 0.0373 × (L1 - 150) (unit: L); the volume of the accumulator airbag is V2 = 4ΔV + V1 = 0.15 × (L1 - 150) + 7.5; At this time, the accumulator pressure P1 = 20 × 7.5 × 1.4 / (0.15 × (L1 - 150) + 7.5) × 1.4, and the vertical component force Fcy of hydraulic cylinder 5 = 4Fc × Δh / (150² + Δh²)¹ / ² = 4P1 × A × Δh / (150² + Δh²)¹ / ² = 4 × 20 × 7.51.4 / (0.15×((1502+Δh2)1 / 2-150)+7.5)1.4×37325.3×10-3×Δh / (1502+Δh2)1 / 2;The relationship curve between F and Δh can be seen in the reference Figure 5 ; When the vertical load transmitted from the superstructure is too large, multiple supports can be used to bear the load simultaneously, thereby reducing the design and manufacturing difficulty of the vertical bearing unit and hydraulic cylinder.

[0054] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A quasi-zero stiffness vibration isolation device based on hydraulic negative stiffness, characterized in that, include: The vertical bearing unit includes at least one vertical spring (3), the two ends of which are respectively connected to the top surface of the lower connecting plate (2) and the bottom surface of the upper connecting plate (1); The negative stiffness unit includes a hydraulic cylinder (5) and a piston rod (6), the piston rod (6) extending into the hydraulic cylinder (5), the hydraulic cylinder (5) and the piston rod (6) being hinged to the lower connecting plate (2) and the upper connecting plate (1) respectively, or the hydraulic cylinder (5) and the piston rod (6) being hinged to the upper connecting plate (1) and the lower connecting plate (2) respectively. The increase or decrease of the distance between the upper connecting plate (1) and the lower connecting plate (2) can drive the length of the piston rod (6) extending into the hydraulic cylinder (5) to decrease or increase, thereby providing negative stiffness.

2. The quasi-zero stiffness vibration isolation device based on hydraulic negative stiffness according to claim 1, characterized in that, It also includes an upper connecting plate (1) and a lower connecting plate (2), the upper connecting plate (1) being connected to the upper support, the lower connecting plate (2) being connected to the lower support, and the two ends of the vertical spring (3) being connected to the upper connecting plate (1) and the lower connecting plate (2) respectively.

3. The quasi-zero stiffness vibration isolation device based on hydraulic negative stiffness according to claim 2, characterized in that, The upper connecting plate (1) is provided with a lower extension (101), and the lower connecting plate (2) is provided with an upper extension (201). The lower extension (101) surrounds the upper extension (201), or the upper extension (201) surrounds the lower extension (101).

4. A quasi-zero stiffness vibration isolation device based on hydraulic negative stiffness according to claim 3, characterized in that, The hydraulic cylinder (5) and the piston rod (6) are connected to the upper connecting plate (1) and the lower connecting plate (2) through the lower extension (101) and the upper extension (201). When the upper connecting plate (1) and the lower connecting plate (2) are both in the initial position, the piston rod (6) extends the shortest length out of the hydraulic cylinder (5).

5. A quasi-zero stiffness vibration isolation device based on hydraulic negative stiffness according to claim 3, characterized in that, Both the lower extension (101) and the upper extension (201) are provided with ear plates (7), and the hydraulic cylinder (5) and the piston rod (6) are both connected to the ear plates (7).

6. A quasi-zero stiffness vibration isolation device based on hydraulic negative stiffness according to any one of claims 1-5, characterized in that, The vertical spring (3) is a helical spring, a ring spring, or a hydraulic spring.

7. A quasi-zero stiffness vibration isolation device based on hydraulic negative stiffness according to any one of claims 1-5, characterized in that, The vertical bearing unit also includes a guide rod (4), which is disposed inside the vertical spring (3).

8. A quasi-zero stiffness vibration isolation device based on hydraulic negative stiffness according to any one of claims 1-5, characterized in that, The vertical bearing unit includes a plurality of vertical springs (3) spaced apart, with adjacent vertical springs (3) having opposite directions of rotation.

9. A quasi-zero stiffness vibration isolation device based on hydraulic negative stiffness according to any one of claims 1-5, characterized in that, The hydraulic cylinder (5) is a double-rod symmetrical cylinder or a single-piston rod cylinder.

10. A design method for a quasi-zero stiffness vibration isolation device based on hydraulic negative stiffness, characterized in that, The method for designing a quasi-zero stiffness vibration isolation device based on hydraulic negative stiffness as described in any one of claims 1-9 includes the following steps: S1, Vertical load transmitted by the upper support pier F and the pre-compression of the vertical spring (3) h 0. Determine the total vertical stiffness of the vertical bearing element. ; S2, according to Vertical displacement of the lower support pier Determine the vertical component of the hydraulic cylinder (5) under the condition of near-zero vertical stiffness. ; S3. Based on the accumulator pressure of the hydraulic cylinder (5) P 1 and the working area of ​​the hydraulic cylinder (5) A Determine the actual thrust of the hydraulic cylinder (5) ; S4, according to , and h 0 Confirmed F and The relational expression is used to complete the design of a seismic isolation system with quasi-zero vertical stiffness.

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