Negative stiffness magnetic liquid pipeline vibration absorption device with eddy current effect

Abstract

The invention relates to the technical field of pipeline vibration energy dissipation, in particular to a negative stiffness magnetic liquid pipeline vibration absorption device with an eddy current effect, which comprises a vibration reduction shell, a copper pipe inner cylinder is arranged in the vibration reduction shell, and a rotor permanent magnet is movably arranged in the copper pipe inner cylinder; two ends of the copper pipe inner cylinder are respectively connected with a first electromagnetic module and a second electromagnetic module, and the first electromagnetic module and the second electromagnetic module generate an induced magnetic field which attracts the rotor permanent magnet after being electrified; a first stator permanent magnet is fixedly mounted on the first electromagnetic module, a second stator permanent magnet is fixedly mounted on the second electromagnetic module, and the first stator permanent magnet and the second stator permanent magnet are mutually exclusive with the rotor permanent magnet in the same polarity; a closed sealing cavity defined by the copper pipe inner cylinder, the first electromagnetic module and the second electromagnetic module is filled with magnetic liquid. Effective combination of the negative stiffness electromagnetic force mechanism, the magnetic liquid and the eddy current damping unit is achieved, and broadband, efficient and semi-active vibration suppression of pipeline vibration is achieved.

Description

Technical Field

[0001] This invention relates to the field of pipeline vibration energy dissipation technology, and in particular to a pipeline vibration absorption device for a negative stiffness magnetic liquid with eddy current effect. Background Technology

[0002] Hydraulic systems commonly experience pressure fluctuations caused by pump pulsation, valve opening and closing, and sudden load changes. These fluctuations are transmitted to pipelines through the fluid medium, causing pipeline structural vibration and radiating noise. In severe cases, this can lead to pipeline fatigue fracture, loose joints, and instrument failure. Traditional pipeline vibration control methods, such as installing rubber hoses, hydraulic pulsation dampers, or dynamic vibration absorbers, have inherent limitations: the damping performance of rubber hoses decreases with age and has a narrow frequency response range; traditional dampers are ineffective at suppressing low-frequency vibrations; and dynamic vibration absorbers require precise tuning and are difficult to adapt to wide-frequency variable operating conditions.

[0003] Eddy current effect, as a classic electromagnetic damping mechanism, has a certain application foundation in the field of vibration control. However, traditional eddy current dampers typically employ the relative motion between a permanent magnet and a conductor plate, which suffers from problems such as low magnetic field utilization, limited damping force density, and insensitivity to low-frequency vibrations. Especially in applications like pipelines where space is limited, the vibration frequency range is wide, and energy is high, traditional eddy current dampers are insufficient to meet practical needs. In recent years, vibration control technology based on smart materials has attracted attention. Magnetic fluids (also known as ferrofluids) have been used in vibration absorber design due to their unique magnetofluid coupling characteristics, but their applications are mostly limited to providing viscous damping or achieving active control. How to fully utilize the physical potential of magnetic fluids to generate frictional damping and dissipate energy in alternating magnetic fields, while simultaneously solving the core problems of passive vibration absorbers having high dynamic stiffness in the low-frequency range and insensitivity to small-amplitude vibrations, has become a technical bottleneck that urgently needs to be overcome in this field. Summary of the Invention

[0004] The purpose of this invention is to provide a pipeline vibration absorption device for negative stiffness magnetic fluid with eddy current effect, so as to solve the problems existing in the prior art.

[0005] To achieve the above objectives, the present invention provides the following solution: The present invention provides a pipeline vibration absorption device for a negative stiffness magnetic liquid with eddy current effect, comprising a vibration damping shell fixed to a hydraulic pipeline, a copper inner cylinder coaxially arranged inside the vibration damping shell, and a moving permanent magnet movably arranged inside the copper inner cylinder; The two ends of the inner cylinder of the copper tube are respectively sealed and connected to a first electromagnetic module and a second electromagnetic module. The first electromagnetic module and the second electromagnetic module are respectively fixed to the vibration damping shell. After the first electromagnetic module and the second electromagnetic module are energized, they generate an induced magnetic field that attracts the moving permanent magnet. A first stator permanent magnet is fixedly installed on the first electromagnetic module, and a second stator permanent magnet is fixedly installed on the second electromagnetic module. The first stator permanent magnet and the second stator permanent magnet are like poles and mutually repulsive with the mover permanent magnet. The inner cylinder of the copper tube, the first electromagnetic module, and the second electromagnetic module form a closed sealed cavity, which is filled with magnetic liquid, and the moving permanent magnet is immersed in the magnetic liquid.

[0006] Preferably, a guide rod is fixedly connected between the first electromagnetic module and the second electromagnetic module, the guide rod is arranged along the center of the inner cylinder of the copper tube, and the moving permanent magnet is slidably sleeved on the guide rod.

[0007] Preferably, the first electromagnetic module includes a first coil frame sealed and connected to the first end of the inner cylinder of the copper tube, the first coil frame being fixedly connected to the inner wall of the vibration damping shell, and a first electromagnetic coil being wound around the outer wall of the first coil frame; the first stator permanent magnet is embedded and fixedly connected to the end of the first coil frame away from the inner cylinder of the copper tube.

[0008] Preferably, the second electromagnetic module includes a second coil frame sealed and connected to the second end of the inner cylinder of the copper tube, the second coil frame being fixedly connected to the inner wall of the vibration damping shell, and a second electromagnetic coil being wound around the outer wall of the second coil frame; the second stator permanent magnet is embedded and fixedly connected to the end of the second coil frame away from the inner cylinder of the copper tube.

[0009] Preferably, the first electromagnetic coil and the second electromagnetic coil have two operating modes: In passive mode, the first electromagnetic coil and the second electromagnetic coil are in an open circuit state, and vibration is reduced by the negative stiffness between the first stator permanent magnet, the second stator permanent magnet and the mover permanent magnet and the eddy current effect of the magnetic fluid. In semi-active mode, the first electromagnetic coil and the second electromagnetic coil are in a closed state, realizing self-sensing of vibration state and active adjustment of stiffness characteristics.

[0010] Preferably, the vibration damping shell includes an outer shell that is clamped to the hydraulic pipeline by a pipe clamp, the inner cylinder of the copper tube is coaxially fixed to the inner cavity of the outer shell, and the first coil frame and the second coil frame are respectively fixed to the inner cavity of the outer shell; the two ends of the outer shell are respectively fitted with an upper end cap and a lower end cap for sealing.

[0011] Preferably, the outer casing has a first coil external interface and a second coil external interface. The first electromagnetic coil is electrically connected to the outside through the first coil external interface, and the second electromagnetic coil is electrically connected to the outside through the second coil external interface.

[0012] Preferably, a first internal sealing ring is provided between the first coil frame and the inner cylinder of the copper tube, and a second internal sealing ring is provided between the second coil frame and the inner cylinder of the copper tube.

[0013] Preferably, a first external sealing ring is provided between the lower end cover and the first coil frame, and a second external sealing ring is provided between the upper end cover and the second coil frame.

[0014] Preferably, the guide rod includes a first half rod and a second half rod that are inserted into each other, the first half rod being fixedly connected to the first electromagnetic module, and the second half rod being fixedly connected to the second electromagnetic module.

[0015] Compared with existing technologies, this invention has the following advantages and technical effects: This invention discloses a pipeline vibration absorption device using a negative stiffness magnetic fluid with eddy current effect. Combining electromagnetic force negative stiffness, magnetic fluid damping, and eddy current effect, it achieves pipeline vibration absorption. The damping shell is clamped onto the pipeline via a fixture bracket. This external suspension installation method eliminates the need for any structural modifications to the original pipeline system when dealing with complex pipeline systems, maintaining the integrity of the original system while greatly simplifying the installation process. It is particularly suitable for vibration control and renovation projects of existing systems. This invention constructs a negative stiffness magnetic field environment using permanent magnets and electromagnetic modules, significantly reducing the equivalent stiffness of the system near the equilibrium point and achieving high sensitivity to minute displacements. Simultaneously, utilizing the adjustable damping characteristic of the magnetic fluid with changes in the magnetic field, when the magnetic fluid adheres to the moving permanent magnet, it moves back and forth with the moving permanent magnet, converting kinetic energy into heat energy through friction. Furthermore, when the central moving permanent magnet vibrates at different speeds, it induces changing eddy currents in the inner cylinder of the copper tube, which efficiently converts the broadband vibration mechanical energy into heat energy for dissipation, effectively suppressing pipeline vibration. The stator permanent magnet and the moving permanent magnet have the same magnetic poles on adjacent surfaces, generating a repulsive force. After the electromagnetic module is energized, the magnetic field it generates attracts the opposite magnetic poles on adjacent surfaces of the central moving permanent magnet, providing electromagnetic negative stiffness. This means that when the moving permanent magnet in the magnetic fluid is at its central equilibrium position, it is subjected to opposite and equal attractive forces on both sides. Any slight deviation will be subject to a force that pushes it further away from the equilibrium position, thus exhibiting negative stiffness characteristics. Attached Figure Description

[0016] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the embodiments will be briefly described below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort. In the drawings: Figure 1 This is an external schematic diagram of the pipeline vibration absorption device for a negative stiffness magnetic liquid with eddy current effect according to the present invention. Figure 2 This is a schematic diagram of the internal structure of the pipeline vibration absorption device for a negative stiffness magnetic liquid with eddy current effect according to the present invention. Figure 3 This is a schematic diagram of the pipeline vibration absorption device for a negative stiffness magnetic liquid with eddy current effect according to the present invention. Figure 4 This is a schematic diagram of the inner cylinder of the copper tube of the present invention; Figure 5 This is a schematic diagram showing the disassembled first coil frame and second coil frame of the present invention; In the diagram: 1. Upper end cover; 2. Second coil frame; 3. Second electromagnetic coil; 4. Guide rod; 5. Copper tube inner cylinder; 6. First electromagnetic coil; 7. First stator permanent magnet; 8. Lower end cover; 9. First external sealing ring; 10. First coil frame; 11. First coil external interface; 12. First internal sealing ring; 13. Outer shell; 14. Mover permanent magnet; 15. Second internal sealing ring; 16. Second coil external interface; 17. Second external sealing ring; 18. Second stator permanent magnet. Detailed Implementation

[0017] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0018] To make the above-mentioned objects, features and advantages of the present invention more apparent and understandable, the present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0019] Reference Figures 1 to 5 As shown, this embodiment provides a pipeline vibration absorption device for a negative stiffness magnetic liquid with eddy current effect, including a vibration damping shell fixed on a hydraulic pipeline, a copper inner cylinder 5 coaxially arranged inside the vibration damping shell, and a moving permanent magnet 14 movably arranged inside the copper inner cylinder 5. The two ends of the inner cylinder 5 of the copper tube are respectively sealed and connected to the first electromagnetic module and the second electromagnetic module. The first electromagnetic module and the second electromagnetic module are respectively fixed to the vibration damping shell. After the first electromagnetic module and the second electromagnetic module are energized, they generate an induced magnetic field that attracts the moving permanent magnet 14. A first stator permanent magnet 7 is fixedly installed on the first electromagnetic module, and a second stator permanent magnet 18 is fixedly installed on the second electromagnetic module. The first stator permanent magnet 7 and the second stator permanent magnet 18 are like poles and mutually repel each other with the mover permanent magnet 14. The inner cylinder 5 of the copper tube, the first electromagnetic module and the second electromagnetic module form a closed sealed cavity, which is filled with magnetic liquid, and the moving permanent magnet 14 is immersed in the magnetic liquid.

[0020] This invention discloses a pipeline vibration absorption device using a negative stiffness magnetic fluid with eddy current effect. Combining electromagnetic force negative stiffness, magnetic fluid damping, and eddy current effect, it achieves pipeline vibration absorption. The damping shell is clamped onto the pipeline via a bracket. This external suspension installation method eliminates the need for any structural modifications to the existing pipeline system when dealing with complex systems, maintaining the integrity of the original system while greatly simplifying the installation process. It is particularly suitable for vibration control and renovation projects of existing systems. This invention constructs a negative stiffness magnetic field environment using permanent magnets and electromagnetic modules, significantly reducing the equivalent stiffness of the system near the equilibrium point and achieving high sensitivity to minute displacements. Simultaneously, utilizing the adjustable damping characteristic of the magnetic fluid with changes in the magnetic field, when the magnetic fluid adheres to the moving permanent magnet 14, it moves back and forth with the moving permanent magnet 14, converting kinetic energy into heat energy through friction. Furthermore, when the central moving permanent magnet 14 vibrates at different speeds, it induces changing eddy currents in the inner cylinder 5 of the copper tube, which efficiently converts the broadband vibration mechanical energy into heat energy dissipation, thus effectively suppressing pipeline vibration. The stator permanent magnet and the moving permanent magnet 14 have the same magnetic poles on their adjacent surfaces, generating a repulsive force. After the electromagnetic module is energized, the magnetic field it generates attracts the opposite magnetic poles on the adjacent surfaces of the central moving permanent magnet 14, providing electromagnetic negative stiffness. This means that when the moving permanent magnet 14 in the magnetic fluid is in the central equilibrium position, it is subjected to opposite and equal attractive forces on both sides. Any slight deviation will be subject to a force that pushes it further away from the equilibrium position, thus exhibiting negative stiffness characteristics.

[0021] In one embodiment of the present invention, the principle of eddy current action mentioned in this embodiment is to generate eddy currents by the movement of a conductor in a magnetic field, thereby converting mechanical energy into heat energy for dissipation. In structural vibration control, eddy current dampers are used for vibration reduction in large structures such as bridges and buildings due to their advantages of being contactless, wear-free, fast-responding, and highly reliable.

[0022] In one embodiment of the present invention, the vibration damping shell is fixed to the hydraulic pipeline by a pipe clamp. The pipe clamp is made of stainless steel and is fastened by bolts. During installation, there is no need to cut, weld or change the pipeline route of the original hydraulic pipeline.

[0023] In one embodiment of the present invention, the inner cylinder 5 of the copper tube is made of pure copper material and is tightly attached to the inner wall of the vibration damping shell. When the vibration of the pipeline is transmitted to the moving permanent magnet 14 and drives it to vibrate along the axial direction, since the moving permanent magnet 14 itself is magnetic, its movement will cause the magnetic flux passing through the inner cylinder 5 of the eddy current copper tube to change rapidly. According to the law of electromagnetic induction, eddy currents will be generated in the sleeve. Under the action of the sleeve's own resistance, the eddy currents are converted into Joule heat, thereby irreversibly dissipating the mechanical energy of the vibration. This is the most important broadband energy dissipation mechanism of this device.

[0024] In one embodiment of the present invention, the wall thickness of the inner cylinder 5 of the copper tube is 1-3 mm, and the magnetic field strength at the inner cylinder 5 of the copper tube can reach 200-300 mT.

[0025] In one embodiment of the present invention, the magnetic fluid adsorbed onto the moving permanent magnet 14 not only lubricates the movement of the moving permanent magnet 14 and reduces solid friction and wear, but its high magnetic permeability also optimizes the magnetic circuit, enhances the magnetic field strength and gradient, thereby improving the efficiency of the eddy current effect. More importantly, the magnetic fluid itself becomes a solid-like state in the magnetic field, providing friction between the moving permanent magnet 14 and the inner wall of the copper tube. When the moving permanent magnet 14 reciprocates axially, the magnetic fluid generates a frictional damping force, converting the kinetic energy of the moving permanent magnet 14 into heat energy for dissipation.

[0026] In one embodiment of the present invention, a magnetic liquid layer is adsorbed on the outer surface of the moving permanent magnet 14, and the thickness of the magnetic liquid layer is 0.5-2 mm.

[0027] In one embodiment of the present invention, the magnetic liquid is a stable colloid formed by suspending nano-sized hollow Fe3O4 particles in a silicone oil-based carrier liquid, with a volume fraction of 15-20% and a saturation magnetization of 50-60 kA / m.

[0028] In a further optimized design, a guide rod 4 is fixedly connected between the first and second electromagnetic modules. The guide rod 4 is arranged along the center of the inner copper tube 5, and the moving permanent magnet 14 is slidably sleeved on the guide rod 4. The guide rod 4 connects the first and second electromagnetic modules, enabling their positioning. Simultaneously, the moving permanent magnet 14 has a ring-shaped design, sliding on the guide rod 4 to allow it to slide freely along the axial direction of the guide rod 4. Furthermore, the guide rod 4 is aligned with the axis of the inner copper tube 5, limiting the direction of movement of the moving permanent magnet 14. This ensures that when the device is subjected to vibration, the moving permanent magnet 14 can only move along the axis of the inner copper tube 5.

[0029] In one embodiment of the present invention, a magnetic liquid layer is provided between the moving permanent magnet 14 and the guide rod 4, so that the moving permanent magnet 14 can move on the guide rod 4 with almost no friction, thereby reducing mechanical wear and improving lifespan and response speed.

[0030] A further optimized design includes guide rod 4 comprising a first half-rod and a second half-rod that are interlocked. The first half-rod is fixedly connected to the first electromagnetic module, and the second half-rod is fixedly connected to the second electromagnetic module. (See appendix) Figure 5 As shown, since the guide rod 4 is connected between the first electromagnetic module and the second electromagnetic module, and the first electromagnetic module and the second electromagnetic module are located at the two ends of the inner cylinder 5 of the copper tube respectively, in order to facilitate the connection between the first electromagnetic module and the second electromagnetic module and the inner cylinder 5 of the copper tube, the guide rod 4 is divided into two parts, the first half rod and the second half rod, which can be plugged in and positioned for connection, so as to facilitate connection and ensure connection quality.

[0031] Further optimizing the scheme, the first electromagnetic module includes a first coil frame 10 sealed and connected to the first end of the inner cylinder 5 of the copper tube. The first coil frame 10 is fixedly connected to the inner wall of the vibration damping shell, and a first electromagnetic coil 6 is wound around the outer wall of the first coil frame 10. A first stator permanent magnet 7 is embedded and fixedly connected to the end of the first coil frame 10 away from the inner cylinder 5 of the copper tube. The second electromagnetic module includes a second coil frame 2 sealed and connected to the second end of the inner cylinder 5 of the copper tube. The second coil frame 2 is fixedly connected to the inner wall of the vibration damping shell, and a second electromagnetic coil 3 is wound around the outer wall of the second coil frame 2. A second stator permanent magnet 18 is embedded and fixedly connected to the end of the second coil frame 2 away from the inner cylinder 5 of the copper tube. The first coil frame 10 is fixed inside the vibration damping shell at one end, serving as a fixed base for the first stator permanent magnet 7 and the first electromagnetic coil 6, while the second coil frame 2 is fixed inside the vibration damping shell at the other end, serving as a fixed base for the second stator permanent magnet 18 and the second electromagnetic coil 3. When the pipeline vibrates due to pressure pulsation or external excitation, the vibration energy is transmitted to the entire device through the pipeline wall. The pipeline vibration drives the moving permanent magnet 14, coupled by a magnetic field, to move axially along the guide rod 4. The moving permanent magnet 14 is subjected to the repulsive force of the like poles of the first stator permanent magnet 7 and the second stator permanent magnet 18 on both sides. The electromagnetic field generated by the first electromagnetic coil 6 and the second electromagnetic coil 3 generates an attractive force on the moving permanent magnet 14, forming a negative stiffness region near the central equilibrium position. Any tiny axial displacement will be subjected to a magnetic force that pushes it further away from the equilibrium position. This greatly reduces the equivalent dynamic stiffness of the system, making the moving magnet extremely sensitive to micro-amplitude low-frequency vibrations. The amplitude is significantly amplified, thereby efficiently transferring the vibration energy of the main structure to the inside of the vibration absorber.

[0032] In one embodiment of the present invention, the first electromagnetic coil 6 and the second electromagnetic coil 3 are wound with enameled copper wire, with 800-1500 turns.

[0033] In one embodiment of the present invention, the mover permanent magnet 14 is made of neodymium iron boron permanent magnet material, with a remanence of 1.2-1.5T and a coercivity of 800-1200kA / m.

[0034] In one embodiment of the present invention, the viscosity of the magnetic liquid is adjustable under the action of a magnetic field, and the variation range is 0.05-5 Pa·s.

[0035] The scheme has been further optimized so that the first electromagnetic coil 6 and the second electromagnetic coil 3 have two operating modes: In passive mode, the first electromagnetic coil 6 and the second electromagnetic coil 3 are in an open circuit state. Vibration reduction is achieved through the negative stiffness between the first stator permanent magnet 7, the second stator permanent magnet 18, and the mover permanent magnet 14, as well as the eddy current effect of the magnetic fluid. In passive vibration reduction mode, the first electromagnetic coil 6 and the second electromagnetic coil 3 are open circuits and do not generate a magnetic field. Vibration reduction mainly relies on the mutual repulsion of the negative stiffness between the first stator permanent magnet 7, the second stator permanent magnet 18, and the mover permanent magnet 14, the frictional resistance of the mover permanent magnet 14 moving in the magnetic fluid, and the eddy current effect of the stator permanent magnet to convert vibration and achieve vibration reduction. In semi-active mode, the first electromagnetic coil 6 and the second electromagnetic coil 3 are in a closed state, realizing self-sensing of vibration state and active adjustment of stiffness characteristics. In semi-active control mode, the first electromagnetic coil 6 and the second electromagnetic coil 3 are connected to an external circuit. When a controllable current is applied, the magnetic field generated by the current is superimposed on the inherent bias magnetic field of the permanent magnet, thereby actively adjusting the magnitude and distribution of the electromagnetic force acting on the mover permanent magnet 14. This allows the negative stiffness characteristics and damping characteristics of the device to be adjusted online to adapt to different working conditions and achieve semi-active control.

[0036] In one embodiment of the present invention, during vibration reduction, the moving permanent magnet 14 moves along the guide rod 4, and the eddy current damping force is proportional to the square of the moving speed of the moving permanent magnet 14. The negative stiffness characteristic makes the equivalent stiffness of the system negative near the equilibrium point, and it has a high sensitivity response to micro-amplitude vibration.

[0037] In one embodiment of the present invention, the invention also includes a sensing mode. In this mode, when the first electromagnetic coil 6 and the second electromagnetic coil 3 are open-circuited or connected to a high-impedance measurement circuit, the change in magnetic flux caused by the movement of the permanent magnet 14 will induce a voltage in the electromagnetic coils. By monitoring the frequency and amplitude of this voltage signal, the vibration state of the pipeline can be deduced in real time, thus realizing a self-sensing function. Simultaneously, using the measurement data as feedback parameters, the current of the first electromagnetic coil 6 and the second electromagnetic coil 3 can be automatically adjusted.

[0038] The design is further optimized. The vibration damping shell includes an outer shell 13 that is clamped onto the hydraulic pipeline via pipe clamps. A copper inner cylinder 5 is coaxially fixed to the inner cavity of the outer shell 13. The first coil frame 10 and the second coil frame 2 are respectively fixed to the inner cavity of the outer shell 13. An upper end cap 1 and a lower end cap 8 are respectively installed at both ends of the outer shell 13 for sealing. The outer shell 13, as the main structure of the device, is directly clamped onto the pipeline via pipe clamps, making connection convenient. The upper end cap 1 and the lower end cap 8 are respectively sealed at the ends of the outer shell 13 to close both ends, providing fixation and protection.

[0039] In one embodiment of the present invention, the outer shell 13 is made of a soft magnetic material with high magnetic permeability, which is used to form a closed magnetic circuit and improve the utilization rate of the magnetic field.

[0040] In a further optimized design, the outer casing 13 is provided with a first coil external interface 11 and a second coil external interface 16. The first electromagnetic coil 6 is electrically connected to the outside through the first coil external interface 11, and the second electromagnetic coil 3 is electrically connected to the outside through the second coil external interface 16.

[0041] In a further optimized design, a first internal sealing ring 12 is provided between the first coil frame 10 and the inner copper tube 5, and a second internal sealing ring 15 is provided between the second coil frame 2 and the inner copper tube 5; a first external sealing ring 9 is provided between the lower end cover 8 and the first coil frame 10, and a second external sealing ring 17 is provided between the upper end cover 1 and the second coil frame 2. The first internal sealing ring 12 and the second internal sealing ring 15 achieve dynamic sealing between the first coil frame 10 and the second coil frame 2, ensuring the sealing performance of the sealing cavity and preventing leakage of magnetic fluid in the sealing cavity; the first external sealing ring 9 and the second external sealing ring 17 achieve static sealing between the upper end cover 1 and the lower end cover 8 and the outer casing 13.

[0042] In one embodiment of the present invention, the materials of the first inner sealing ring 12, the second inner sealing ring 15, the first outer sealing ring 9 and the second outer sealing ring 17 are fluororubber or nitrile rubber, and the temperature resistance range is -40°C to 200°C.

[0043] Assembly process: Press-fit the first stator permanent magnet 7 into the designated annular groove within the first coil frame 10, ensuring its magnetic pole direction matches the design requirements, typically with the N pole facing upwards. Tightly wind the first electromagnetic coil 6 into the winding groove of the first coil frame 10, and connect its lead end to the first coil external interface 11. Install the first external sealing ring 9 into the sealing groove of the lower end cover 8. Align and securely connect the first coil frame 10, pre-assembled with the stator permanent magnet and coil, to the lower end cover 8.

[0044] The second stator permanent magnet 18 is press-fitted and fixed in the designated annular groove within the second coil frame 2, ensuring that its magnetic poles are attracted to the first stator permanent magnet 7. The second electromagnetic coil 3 is tightly wound into the winding groove of the second coil frame 2, and its lead end is connected to the second coil external interface 16. The second external sealing ring 17 is installed in the sealing groove of the upper end cover 1. The second coil frame 2, pre-loaded with the permanent magnet and coil, is aligned with the upper end cover 1, ensuring that it is repelled by the magnetic poles of the second stator permanent magnet 18, and then fixedly connected.

[0045] The inner tube 5 of the copper tube is installed inside the outer shell 13. The moving permanent magnet 14 is passed through the guide rod 4 of the second coil frame 2, allowing it to slide freely along the axial direction of the guide rod 4. A suitable amount of magnetic liquid is uniformly adsorbed on the outer surface of the moving permanent magnet 14. This magnetic liquid layer is key to achieving lubrication, magnetic conduction, and additional frictional damping. The lower end of the guide rod 4, which is equipped with the moving permanent magnet 14, is inserted and fixed into the center positioning hole of the pre-installed lower component, i.e., the first coil frame 10. The first internal sealing ring 12 and the second internal sealing ring 15 are respectively installed on the sealing surfaces of the first coil frame 10 and the second coil frame 2 that mate with the inner tube 5 of the copper tube. The upper component is slowly pressed down along the upper end of the guide rod 4, so that the first half rod and the second half rod are aligned and inserted, and the second coil frame 2 is precisely connected to the first coil frame 10. The upper and lower end caps 8 are firmly connected to the outer shell 13 by bolts or other fasteners to form a complete sealed cavity. During this process, ensure that the inner tube 5 of the copper tube is pressed and fixed between the first coil frame 10 and the second coil frame 2.

[0046] In summary, the technical solution of the present invention has the following advantages: 1. Permanent magnet magnetic springs are used to replace traditional springs to provide restoring force. By adjusting the current, the magnitude of the electromagnetic field generated by the electromagnetic coil is changed, so that the stiffness of the vibration absorber can be negative according to a certain law. This allows the device to achieve targeted energy transfer with the main structure. This transfer has the characteristics of fast transfer speed and unidirectional irreversibility.

[0047] 2. When the moving permanent magnet 14 is in its equilibrium position, it is balanced by the magnetic field of the stator permanent magnet. When pipeline vibration drives the moving permanent magnet 14 to undergo a small axial displacement, due to the nonlinear characteristics of the electromagnetic coil's magnetic circuit design, the direction of its restoring force is the same as the direction of displacement within a specific range, resulting in a negative stiffness effect. This significantly reduces the equivalent dynamic stiffness of the system near the equilibrium point, making the vibration absorber extremely sensitive to small, low-frequency pipeline vibrations. The negative stiffness design enables the device to respond excellently to low-frequency micro-amplitude vibrations, and combined with the high-frequency effectiveness of eddy current damping, it achieves wideband, high-efficiency vibration absorption from low to mid-high frequencies.

[0048] 3. Magnetic fluid is a smart nanomaterial with advantages such as superparamagnetism, second-order buoyancy, and low damping. Due to the action of the magnetic fluid, the moving permanent magnet 14 and the guide rod 4 are in a liquid friction environment, eliminating mechanical friction. This avoids damage to the device caused by solid-solid friction, improves the device's service life while lubricating it, and increases the device's response speed to pipeline vibration, thus enhancing its sensitivity. The magnetic fluid replaces air and fills the space between the moving permanent magnet 14 and the inner copper tube 5. Due to its superparamagnetism and high permeability, the magnetic fluid can effectively absorb and conduct magnetic fields, increasing the sensitivity and response intensity of the electromagnetic coil wound on the coil frame. According to the law of electromagnetic induction, under the same conditions, the greater the change in magnetic field magnitude, the greater the induced current. Compared with traditional vibration absorbers, this vibration absorber has a higher vibration energy consumption efficiency.

[0049] 4. The inner copper tube 5, acting as the key eddy current generator, is fixedly installed inside the vibration absorber. When the pipeline vibration is transmitted to the vibration absorber, driving the permanent magnet 14 to reciprocate in the magnetic field, its motion causes a rapid change in the magnetic flux passing through the copper tube wall. According to Faraday's law of electromagnetic induction, this changing magnetic field induces a strong eddy current within the copper tube, a good conductor. Under the influence of the copper tube's own resistance, this eddy current efficiently and irreversibly converts the mechanical energy of the vibration into Joule heat, which is then dissipated, thus achieving the purpose of vibration absorption.

[0050] 5. The electromagnetic coil is wound on a coil frame. This coil can operate in two modes: Passive mode: the coil is open-circuited or unconnected to a load, requiring no external power supply; the device operates entirely based on the passive magnetic negative stiffness and eddy current effect described above. Semi-active mode: the coil is connected to an external circuit. By detecting the voltage or current induced by the coil due to changes in the magnetic field, the vibration state of the pipeline can be inferred, achieving self-sensing; conversely, control current can be applied to the coil.

[0051] 6. The device has an overall ring sleeve structure. The vibration absorber is installed into the pipeline using pipe clamps. This external suspension installation method has no moving parts that are rigidly connected to the pipeline. When dealing with complex pipeline systems, there is no need to change the original structure of the pipeline. The installation is simple and convenient, with strong anti-interference ability and stable and reliable operation.

[0052] In the description of this invention, it should be understood that the terms "longitudinal", "lateral", "up", "down", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, and are only for the convenience of describing this invention, and are not intended to indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this invention.

[0053] The embodiments described above are merely preferred embodiments of the present invention and are not intended to limit the scope of the present invention. Various modifications and improvements made by those skilled in the art to the technical solutions of the present invention without departing from the spirit of the present invention should fall within the protection scope defined by the claims of the present invention.

Claims

1. A pipeline vibration damping device for a negative stiffness magnetic fluid with eddy current effect, characterized in that: Includes a vibration damping shell fixed to the hydraulic pipeline, and a copper tube inner cylinder (5) is coaxially arranged inside the vibration damping shell, and a moving permanent magnet (14) is movably arranged inside the copper tube inner cylinder (5). The two ends of the inner cylinder of the copper tube (5) are respectively sealed and connected to the first electromagnetic module and the second electromagnetic module. The first electromagnetic module and the second electromagnetic module are respectively fixed to the vibration damping shell. After the first electromagnetic module and the second electromagnetic module are energized, they generate an induced magnetic field that attracts the moving permanent magnet (14). A first stator permanent magnet (7) is fixedly installed on the first electromagnetic module, and a second stator permanent magnet (18) is fixedly installed on the second electromagnetic module. The first stator permanent magnet (7) and the second stator permanent magnet (18) are like poles and mutually repulsive with the mover permanent magnet (14). The inner cylinder of the copper tube (5), the first electromagnetic module and the second electromagnetic module form a closed sealed cavity, which is filled with magnetic liquid, and the moving permanent magnet (14) is immersed in the magnetic liquid.

2. The pipeline vibration absorption device for a negative stiffness magnetic fluid with eddy current effect according to claim 1, characterized in that: A guide rod (4) is fixed between the first electromagnetic module and the second electromagnetic module. The guide rod (4) is arranged along the center of the inner cylinder (5) of the copper tube, and the moving permanent magnet (14) is slidably sleeved on the guide rod (4).

3. The pipeline vibration absorption device for a negative stiffness magnetic fluid with eddy current effect according to claim 1, characterized in that: The first electromagnetic module includes a first coil frame (10) sealed and connected to the first end of the inner cylinder of the copper tube (5), the first coil frame (10) being fixedly connected to the inner wall of the vibration damping shell, and a first electromagnetic coil (6) being wound around the outer wall of the first coil frame (10); the first stator permanent magnet (7) is embedded and fixedly connected to the end of the first coil frame (10) away from the inner cylinder of the copper tube (5).

4. The pipeline vibration absorption device for a negative stiffness magnetic fluid with eddy current effect according to claim 3, characterized in that: The second electromagnetic module includes a second coil frame (2) sealed and connected to the second end of the inner cylinder (5) of the copper tube. The second coil frame (2) is fixed to the inner wall of the vibration damping shell. A second electromagnetic coil (3) is wound around the outer wall of the second coil frame (2). The second stator permanent magnet (18) is embedded and fixed at the end of the second coil frame (2) away from the inner cylinder (5).

5. The pipeline vibration absorption device for a negative stiffness magnetic fluid with eddy current effect according to claim 4, characterized in that: The first electromagnetic coil (6) and the second electromagnetic coil (3) have two operating modes: In passive mode, the first electromagnetic coil (6) and the second electromagnetic coil (3) are in an open circuit state, and vibration is reduced by the negative stiffness and eddy current effect of the magnetic fluid between the first stator permanent magnet (7), the second stator permanent magnet (18) and the mover permanent magnet (14); In semi-active mode, the first electromagnetic coil (6) and the second electromagnetic coil (3) are in the closed state, realizing self-sensing of vibration state and active adjustment of stiffness characteristics.

6. The pipeline vibration absorption device for a negative stiffness magnetic fluid with eddy current effect according to claim 4, characterized in that: The vibration damping shell includes an outer shell (13) clamped to the hydraulic pipeline by a pipe clamp. The inner cylinder (5) of the copper tube is coaxially fixed to the inner cavity of the outer shell (13). The first coil frame (10) and the second coil frame (2) are respectively fixed to the inner cavity of the outer shell (13). The two ends of the outer shell (13) are respectively fitted with an upper end cover (1) and a lower end cover (8) for sealing.

7. The pipeline vibration absorption device for a negative stiffness magnetic fluid with eddy current effect according to claim 6, characterized in that: The outer casing (13) is provided with a first coil external interface (11) and a second coil external interface (16). The first electromagnetic coil (6) is electrically connected to the outside through the first coil external interface (11), and the second electromagnetic coil (3) is electrically connected to the outside through the second coil external interface (16).

8. The pipeline vibration absorption device for a negative stiffness magnetic fluid with eddy current effect according to claim 6, characterized in that: A first internal sealing ring (12) is provided between the first coil frame (10) and the inner tube of the copper tube (5), and a second internal sealing ring (15) is provided between the second coil frame (2) and the inner tube of the copper tube (5).

9. The pipeline vibration absorption device for a negative stiffness magnetic fluid with eddy current effect according to claim 6, characterized in that: A first external sealing ring (9) is provided between the lower end cover (8) and the first coil frame (10), and a second external sealing ring (17) is provided between the upper end cover (1) and the second coil frame (2).

10. The pipeline vibration absorption device for a negative stiffness magnetic fluid with eddy current effect according to claim 2, characterized in that: The guide rod (4) includes a first half rod and a second half rod that are inserted into each other. The first half rod is fixedly connected to the first electromagnetic module, and the second half rod is fixedly connected to the second electromagnetic module.

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