An eddy current damping device using a lever mechanism

Abstract

The invention discloses an eddy current damping device using a lever mechanism, comprising a permanent magnet array, a lever clamp, a lever shaft, a first lever cover plate, a second lever cover plate, a shaft sleeve, a self-lubricating slide plate, a bolt, an ear seat, a first adjusting screw, a support column, an inner magnetic steel plate, an outer magnetic steel plate, an inner conductor, an outer conductor and a second adjusting screw. The eddy current damping device is connected to a TMD mass block and a base. The device of the invention greatly reduces the amount of permanent magnets used, utilizes the double-sided magnetic field of the permanent magnet, and obtains the required damping force with a small amount of permanent magnets through an amplification mechanism, thereby reducing the difficulty and risk of permanent magnet installation; it has a large bearing capacity, low friction, and high durability; it has a magnetic shielding measure, which can reduce the impact of the magnetic field on the surrounding environment; it can realize continuous stepless adjustment of the magnetic field gap, that is, it can steplessly adjust the damping force; it has stable performance under TMD vibration with a high number of cycles, and the temperature rises slowly.

Description

Technical Field

[0001] The invention relates to the field of vibration reduction of structures and machinery such as buildings, bridges and structures, and in particular to an eddy current damping device using a lever mechanism. Background Art

[0002] As buildings and bridges develop towards super-high and super-large spans, their structures are prone to generate large vibrations under the excitation of external loads. When the excitation force frequency is close to the natural frequency of the structure, the structure will cause large vibrations due to resonance, and even cause serious consequences. Tuned Mass Damper (TMD) is a vibration control device widely used in building and bridge engineering. TMD uses the inertial system to absorb structural vibration energy and generate resonance with phase difference to reduce the acceleration, displacement and load caused by the resonance effect of buildings or bridges under wind and pedestrian loads. TMD is a vibration mechanism connected to the controlled structure, which consists of three units: mass, stiffness and damping. The optimal vibration reduction efficiency is obtained by adjusting the relationship between the parameters of these three units and the mass and natural frequency of the controlled structure. In addition, due to the deviation between the design mass and natural frequency of the controlled structure and the actual situation, the vibration frequency and damping of TMD need to be further adjusted according to the actual situation after the completion of the project.

[0003] Traditional TMDs consist of a mass unit made of steel, a stiffness unit made of springs or slings, and a damping unit made of a liquid viscous damper. The liquid viscous damper used in traditional TMDs has the following problems: 1) The damping force cannot be adjusted after installation; 2) The seal ring is easily worn during frequent operation, causing oil leakage, and is a consumable part that needs to be replaced; 3) Because the seal ring tightens the piston rod, the friction is large and the damper is difficult to start; 4) Temperature changes have a significant impact on the damping performance.

[0004] At present, technicians use eddy current dampers instead of liquid viscous dampers on TMD, but most of them are single-sided plate eddy current dampers. The eddy current damper provides damping force through the Lorentz force generated by the relative movement between the permanent magnet and the conductor on one side. Specifically, there is a gap (magnetic field gap) between the permanent magnet and the conductor. The relative movement of the two causes the magnetic field of the permanent magnet to cut the conductor, and induced eddy currents are generated in the conductor. The electromagnetic field of the induced eddy current is opposite to the magnetic field of the permanent magnet, and a damping force is generated to hinder the relative movement of the permanent magnet and the conductor. The damping force is proportional to the relative movement speed and increases sharply as the magnetic field gap decreases. Most of the existing eddy current dampers are single-sided plate eddy current dampers, such as patents 2013100804643 and 2016108706498. The plane or curved surface formed by the permanent magnet array is parallel to the plane or curved surface formed by the conductor and there is a gap, which generates relative movement on the plane or curved surface.

[0005] However, the plate-type eddy current damper has the following problems: 1) When vibration occurs perpendicular to the plane or curved surface of the permanent magnet and the conductor, it is difficult to ensure the magnetic field gap, the damping force is unstable, and the permanent magnet and the conductor are prone to collision when the magnetic field gap is small; 2) When the required area of ​​the permanent magnet and the conductor is large, due to processing and installation errors and self-weight deformation, the magnetic field gap is difficult to ensure and the damping force deviation is difficult to control; 3) Due to problems 1) and 2), the magnetic field gap cannot be made very small, and the magnetic field energy utilization rate is not high; 4) Only the magnetic field on one side of the permanent magnet is used, and no conductor is set on the other side, so the magnetic field utilization rate is not high; 5) The large area is not easy to arrange; 6) The permanent magnet has a large suction force (the suction force of the larger permanent magnet is usually tens of kilograms), and the number is large, making it difficult to install by manpower, and permanent magnets are often damaged or injuries occur during installation.

[0006] In order to overcome the problems of plate-type eddy current dampers, scientific researchers have developed other types of eddy current dampers. For example, patent 201610895139 provides an intelligent eddy current inductive damping device, in which a piston rod is inserted in the center of the electromagnetic shielding cover, a permanent magnet unit is connected to the bottom of the piston rod, a copper conductor is fixed inside the electromagnetic shielding cover, a permanent magnet is fixed at the bottom of the copper conductor, and the permanent magnet unit at the bottom of the piston rod and the permanent magnet at the bottom of the copper conductor are relatively displaced during the movement of the piston rod, generating a damping force.

[0007] Patent 2014104755284 discloses a large axial eddy current damper made by spiral transmission, including a transmission component and an eddy current damping generator. The transmission component includes a spiral transmission pair (ball screw) and a stator and a rotor made of magnetic conductive material; the screw of the spiral transmission pair passes through the damper body, the stator is arranged on the upper and lower flanges, the rotor includes an outer rotor and an inner rotor with a lower connecting flange at the bottom, and one or more eddy current damping generators (permanent magnets and conductors) are arranged between the stator and the outer rotor. The device adopts ball screw transmission, and the axial force applies pressure to the ball, and the axial motion is converted into rotational motion around the axis through the threaded raceway guide. Since the ball screw uses steel balls as the operating load, the load-bearing capacity is low, and the lubrication conditions are high, and oil lubrication must be regularly filled. At the same time, the requirements for the use environment have also been improved, and attention should be paid to dust prevention to prevent impurities from entering the raceway.

[0008] Patent CN207437653U discloses a seat-type internal rotation type axial eddy current damper, the inner cylinder of the damper can rotate in the outer cylinder, multiple groups of eddy current damping components are arranged along the axial direction of the inner cylinder or the outer cylinder, the coil components of the eddy current damping components are wound on the outer wall of the inner cylinder along the axial direction, and the magnetic sheet of the magnetic component is arranged on the inner wall of the outer cylinder along the axial direction. The device also uses internal rotation to realize the movement of the magnetic sheet and improve the utilization rate of the magnetic field.

[0009] At present, although some of the above-mentioned eddy current dampers have amplified the damping effect, their structure is relatively complex and their load-bearing capacity is low. Most of them adopt internal rotation, which has very high requirements on the transmission structure. In the absence of lubrication, the friction is large, the wear is serious, and the maintenance is difficult. Moreover, the damping force cannot be adjusted according to the debugging requirements of TMD. Summary of the invention

[0010] The purpose of the present invention is to provide an eddy current damping device using a lever mechanism to solve some problems existing in the prior art, including the large number of permanent magnets, difficult installation, the influence of the magnetic field on the surrounding environment, complex structure, low bearing capacity, high requirements for the transmission structure, large friction without lubrication, severe wear, difficult maintenance, and the damping force cannot be adjusted according to the debugging requirements of the TMD.

[0011] The present invention is implemented by the following technical scheme: an eddy current damping device using a lever mechanism, comprising a permanent magnet array, a lever splint, a lever shaft, a first lever cover plate, a second lever cover plate, a bushing, a self-lubricating slide plate, a bolt, an ear seat, a first adjusting screw, a support column, an inner magnetic steel plate, an outer magnetic steel plate, an inner conductor, an outer conductor and a second adjusting screw, wherein the permanent magnet array is connected to the lever shaft through a connecting mechanism, an inner conductor is provided on one side of the permanent magnet array, and an assembly mechanism is provided on the inner conductor.

[0012] Preferably, the connecting mechanism includes a lever clamp fixedly connected to the permanent magnet array, the permanent magnet array is connected to one end of the lever shaft by screws through the lever clamp, and the circular hole in the middle of the lever shaft is equipped with a bushing and fixed by screws through a first lever cover plate.

[0013] Preferably, an oblong hole is provided at the other end of the lever shaft, the bolt is movably sleeved in the oblong hole, and one end of the bolt is fixed to the TMD mass block.

[0014] Preferably, the diameter of the oblong hole is larger than the bolt, and a second lever cover plate is installed with screws at the top and bottom, and the self-lubricating slide plate is fixed with screws on the side of the second lever cover plate facing the oblong hole.

[0015] Preferably, the mounting mechanism comprises a shaft sleeve, wherein a bolt passes through the shaft sleeve and is connected to a circular hole of an ear seat, and the ear seat is connected to a support column whose bottom is fixed on the TMD base.

[0016] Preferably, the ear seat is connected to the oblong hole at the top of the support column whose bottom is fixed on the TMD base by screws, and the fixing position of the ear seat can be adjusted forward and backward along the oblong hole.

[0017] Preferably, the assembly mechanism comprises an inner conductor and an outer conductor, the permanent magnet array is placed between the inner conductor and the outer conductor and maintains a certain gap, and the inner conductor and the outer side are fixed to the TMD mass block by a second adjusting screw.

[0018] Preferably, the assembly structure further includes an inner magnetic conductive steel plate and an outer magnetic conductive steel plate, and the inner conductor and the outer conductor are overlapped with the inner magnetic conductive steel plate and the outer magnetic conductive steel plate respectively.

[0019] Preferably, a nut is provided on the second adjusting screw, and the gap between the inner conductor and the outer conductor can be adjusted by the nut on the second adjusting screw.

[0020] The eddy current damping device is installed in the TMD as its damping system. Specifically, the bolts (8) and the inner magnetic steel plate (12) are bolted and welded to the TMD mass block respectively, and the bottom of the support column (11) is screwed or welded to the TMD base.

[0021] Advantages of the present invention:

[0022] 1. The relative motion speed between the permanent magnet and the conductor is amplified by a lever mechanism, and a small amount of permanent magnets are used to obtain the required damping force through the amplification mechanism, thereby greatly reducing the amount of permanent magnets used; the damping force of the damping device of the present invention is F=CV(L 2 / L 1 +1) 2 , where C is the permanent magnet damping coefficient; V is the TMD vibration velocity; L 2 L is the distance from the center of the permanent magnet to the center of the bolt (8); 1 is the distance from the center of the bolt (8) to the center of the bolt (8). For example, the amplitude and speed are magnified by 2 times (L 2 / L 1 =2) can amplify the damping force by 9 times.

[0023] 2. The double-sided magnetic field of the permanent magnet can balance the suction force on both sides and improve the utilization rate of the magnetic field, further reducing the amount of permanent magnets used;

[0024] 3. Reducing the amount of permanent magnets can reduce the difficulty and risk of permanent magnet installation;

[0025] 4. The lever mechanism has a large load-bearing capacity and can be used for TMDs with larger load requirements;

[0026] 5. The device has low friction and high durability;

[0027] 6. The outer magnetic steel plate has a magnetic shielding effect while increasing the damping effect, which can reduce the impact of the magnetic field on the surrounding environment;

[0028] 7. It can realize continuous stepless adjustment of magnetic field gap, that is, it can steplessly adjust damping force;

[0029] 8. The performance is stable under high cycle times and the temperature rises slowly. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0031] Figure 1 It is a front structural schematic diagram of the eddy current damping device of the present invention;

[0032] Figure 2 It is a schematic diagram of the top view of the structure of the eddy current damping device of the present invention;

[0033] Figure 3 It is a schematic diagram of the side structure of the eddy current damping device of the present invention;

[0034] Figure 4 A schematic diagram of the front structure of a TMD equipped with the eddy current damping device of the present invention;

[0035] Figure 5 A schematic diagram of the top view of the TMD in which the eddy current damping device of the present invention is installed;

[0036] Figure 6 This is a graph of experimental data of free decay of a TMD installed with the eddy current damping device of the present invention when the damping device is adjusted to different magnetic field gaps.

[0037] In the figure: 1. permanent magnet array; 2. lever splint; 3. lever shaft; 4. first lever cover plate; 5. second lever cover plate; 6. bushing; 7. self-lubricating slide plate; 8. bolt; 9. ear seat; 10. first adjusting screw; 11. support column; 12. inner magnetic steel plate; 13. outer magnetic steel plate; 14. inner conductor; 15. outer conductor; 16. second adjusting screw; 17. TMD mass block; 18. TMD spring; 19. eddy current damping device. DETAILED DESCRIPTION

[0038] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0039] Example 1

[0040] like Figure 1-5 As shown, the present invention provides a technical solution: a TMD installed with an eddy current damping device utilizing a lever mechanism, comprising a TMD mass block 17, a TMD spring 18 and an eddy current damping device 19 consisting of a permanent magnet array 1, a lever splint 2, a lever shaft 3, a first lever cover plate 4, a second lever cover plate 5, a bushing 6, a self-lubricating slide plate 7, a bolt 8, an ear seat 9, a first adjusting screw 10, a support column 11, an inner magnetic steel plate 12, an outer magnetic steel plate 13, an inner conductor 14, an outer conductor 15 and a second adjusting screw 16.

[0041] The permanent magnet array 1 is connected to the lever shaft 3 through a connecting mechanism, and the connecting mechanism includes a lever clamp 2 fixedly connected to the permanent magnet array 1. The permanent magnet array 1 is connected to the left end (enlarged end) of the lever shaft 3 by screws through the lever clamp 2. The shaft sleeve 6 is installed in the circular hole near the middle of the lever shaft 3 and is fixed by screws through the first lever cover plate 4. The right end (transmission end) of the lever shaft 3 is provided with an oblong hole with a diameter larger than the bolt 8. A second lever cover plate 5 is installed with screws above and below the oblong hole. The second lever cover plate 5 is fixed with screws on the side facing the oblong hole to fix the self-lubricating slide plate 7, and the bolt 8 is movably sleeved in the oblong hole.

[0042] The bolt 8 passes through the shaft sleeve 6 and is connected to the circular hole of the ear seat 9. The ear seat 9 is connected to the oblong hole on the top of the support column 11 whose bottom is fixed to the TMD base with a screw. The fixed position of the ear seat 9 can be adjusted forward and backward along the oblong hole. An inner conductor 14 and an outer conductor 15 are provided on both sides of the permanent magnet array 1. The permanent magnet array 1 is placed between the inner conductor 14 and the outer conductor 15 and maintains a certain gap. The inner conductor 14 and the outer conductor 15 are respectively overlapped with the inner magnetic steel plate 12 and the outer magnetic steel plate 13, and are fixed to the TMD mass block 17 with a second adjusting screw 16. The gap between the inner conductor 14 and the outer conductor 15 can be adjusted by the nut on the second adjusting screw 16. By adjusting the gap between the inner conductor 14 and the outer conductor 15 and the position of the ear seat 9 on the support column 11, the gap between the permanent magnet and the conductor can be infinitely adjusted, thereby adjusting the damping force.

[0043] Two eddy current damping devices 19 are arranged on both sides of the TMD mass block 17 as its damping system. Specifically, the bolts (8) and the inner magnetic steel plate (12) are bolted and welded to the TMD mass block 17 respectively, and the bottom of the support column (11) is screwed or welded to the TMD base.

[0044] Working principle: When the TMD mass block 17 vibrates on the TMD spring 18, the bolt 8 drives the right end (transmission end) of the lever, so that the permanent magnet array 1 at the left end (amplification end) of the lever moves between the inner conductor 14 and the outer conductor 15. Its amplitude and movement speed are amplified by the lever principle, and the two magnetic poles of the permanent magnet act on the conductor plates on both sides at the same time. Since the conductor plate is set on the TMD mass block 17 and moves in the opposite direction to the permanent magnet, the relative movement speed of the permanent magnet and the conductor is increased. The relative movement of the permanent magnet and the conductor generates induced eddy currents in the conductor. The electromagnetic field of the induced eddy currents is opposite to the magnetic field of the permanent magnet, and generates a damping force that hinders the relative movement of the permanent magnet and the conductor, and the magnetic steel plate will amplify the eddy current effect in the conductor. Due to the above-mentioned amplification effect, only a small amount of permanent magnets is needed to achieve the damping required by TMD. The transmission of the lever mechanism is relatively simple and direct, and increasing the cross section of the lever can easily achieve a larger bearing capacity. The use of the shaft sleeve 6 and the self-lubricating slide plate 7 can increase the wear resistance of the lever mechanism without adding lubricating oil, greatly extending the service life. If the damping force needs to be adjusted after the TMD is assembled, the gap between the permanent magnet and the conductor can be adjusted, and the gaps on both sides of the permanent magnet must be kept consistent. The above is the entire working principle of the present invention.

[0045] Example 2

[0046] The damping performance test of the device of the present invention is carried out

[0047] Experimental method: For a TMD equipped with the eddy current damping device of the present invention, the damping device is adjusted to different magnetic field gaps, and the TMD is artificially excited to vibrate. After the excitation, the TMD is allowed to vibrate freely, the time history data of the acceleration is recorded, and the damping ratio of the TMD is analyzed.

[0048] The TMD is a vertical vibration, consisting of a 700 kg steel mass supported by four springs, with a natural frequency of 2.5 Hz;

[0049] Experimental results: Figure 6 As shown in the figure, as the magnetic field gap decreases from 15mm to 5mm, the TMD acceleration decay gradually accelerates. Experiments have shown that a small amount of permanent magnets can pass through the eddy current damping device to achieve the damping ratio required for TMD, and the optimal damping ratio of TMD can be achieved by adjusting the magnetic field gap of the eddy current damping device.

[0050] 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, improvements, etc. made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims

1. An eddy current damping device using a lever mechanism, comprising a permanent magnet array (1), a lever clamp (2), a lever shaft (3), a first lever cover plate (4), a second lever cover plate (5), a shaft sleeve (6), a self-lubricating slide plate (7), a bolt (8), an ear seat (9), a first adjusting screw (10), a support column (11), an inner magnetic steel plate (12), an outer magnetic steel plate (13), an inner conductor (14), an outer conductor (15) and a second adjusting screw (16), characterized in that: The permanent magnet array (1) is connected to the lever shaft (3) via a connecting mechanism; an inner conductor (14) is provided on one side of the permanent magnet array (1); an assembly mechanism is provided on the inner conductor (14); the connecting mechanism comprises a lever clamp (2) fixedly connected to the permanent magnet array (1); the permanent magnet array (1) is connected to one end of the lever shaft (3) via the lever clamp (2) by means of screws; an oblong hole is provided at the other end of the lever shaft (3); the bolt (8) is movably sleeved in the oblong hole; one end of the bolt (8) is fixed to the TMD mass block (17); the assembly mechanism comprises an inner conductor (14) and an outer conductor (15); the permanent magnet array (1) is placed between the inner conductor (14) and the outer conductor (15) to maintain a certain gap.

2. The eddy current damping device using a lever mechanism according to claim 1, characterized in that: The circular hole in the middle of the lever shaft (3) is provided with a shaft sleeve (6) and is fixed by screws through the first lever cover plate (4).

3. The eddy current damping device using a lever mechanism according to claim 2, characterized in that: The diameter of the oblong hole is larger than the bolt (8), and a second lever cover plate (5) is mounted on the upper and lower sides by screws. The second lever cover plate (5) is fixed with a self-lubricating slide plate (7) on the side facing the oblong hole by screws.

4. The eddy current damping device using a lever mechanism according to claim 2, characterized in that: The shaft sleeve (6) is connected to the circular hole of the ear seat (9) through a bolt, and the ear seat (9) is connected to a support column (11) fixed at the bottom on the TMD base.

5. The eddy current damping device using a lever mechanism according to claim 4, characterized in that: The ear seat (9) is connected to the oblong hole at the top of the support column (11) whose bottom is fixed on the TMD base by screws, and the fixing position of the ear seat (9) can be adjusted forward and backward along the oblong hole.

6. The eddy current damping device using a lever mechanism according to claim 1, characterized in that: The inner conductor (14) and the outer conductor (15) are fixed to the TMD mass block (17) via a second adjusting screw (16).

7. The eddy current damping device using a lever mechanism according to claim 6, characterized in that: The assembly mechanism further comprises an inner magnetic conductive steel plate (12) and an outer magnetic conductive steel plate (13), and the inner conductor (14) and the outer conductor (15) are respectively overlapped with the inner magnetic conductive steel plate (12) and the outer magnetic conductive steel plate (13).

8. The eddy current damping device using a lever mechanism according to claim 7, characterized in that: A nut is arranged on the second adjusting screw (16), and the gap between the inner conductor (14) and the outer conductor (15) can be adjusted by the nut on the second adjusting screw (16).

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