Particle collision damper based on magnetic liquid suspension properties

Abstract

Particle collision damper based on magnetic liquid suspension characteristics belongs to the field of vibration control. It successfully solves the problem that the existing particle collision damper cannot be applied to low-frequency vibration and weightless environment. The damper comprises a ball (1), a magnetic liquid (2), a bottom magnetic source (3), a shell (4), a side magnetic source (5), a top magnetic source (6), a side magnetic source (7), a ball shell (8) and a filling material (9). When the external vibration occurs, the ball (1) moves and collides in the shell (4), generating fluid viscous damping and collision damping to absorb energy and achieve the purpose of vibration reduction.

Description

Technical Field

[0001] This invention belongs to the field of vibration control in mechanical engineering (including machines, mechanisms and various parts under gravity and weightlessness environments). Background Technology

[0002] Particle collision dampers are passive dampers that dissipate vibration energy through collisions between particles under external vibration excitation. They are applicable to high vibration frequencies and have advantages such as simple structure and long lifespan. However, existing particle collision dampers cannot solve low-to-medium frequency vibration problems due to the high friction between solid particles. They are ineffective at suppressing vibrations below 1000Hz, and are essentially ineffective for vibrations below 100Hz or even lower frequencies. Moreover, current particle dampers rely on gravity to cause particles to accumulate in the shell and generate friction. In a weightless environment, the particles will be in a free-floating state, unable to generate effective collisions, leading to failure.

[0003] To improve the collision probability between particles and the vibration reduction efficiency of particle collision dampers, methods such as injecting a suitable amount of viscous liquid into the container or combining multiple particle collision dampers are commonly used. For example, in Reference 1 (patent application CN106930425 B), the particles are designed as a nested spherical structure connected by springs, and the viscous liquid is used to increase the collision probability between particles. However, the ratio of air to particles inside the nested sphere needs to be properly adjusted to ensure the sphere's suspension, increasing the manufacturing difficulty of the particle damper. Furthermore, the use of springs limits the damper's lifespan. In addition, this design results in the equivalent density of the entire nested sphere being the same as the density of the viscous liquid, making it impossible to generate effective relative motion between the nested sphere and the viscous liquid. Finally, this design is significantly affected by gravity. In space, due to the absence of gravity, the entire nested sphere and its internal particles are in a free-floating state, unable to undergo effective mutual collisions under vibration. In a ground-based environment, gravity causes the particles inside the nested spheres to completely accumulate together. Vibrational energy can only generate movement by overcoming the solid friction between the particles, thus resulting in poor vibration suppression for low and mid-frequency vibrations. However, as described in Reference 2 (patent application CN 114962514 B), the sphere is suspended in a cavity filled with magnetic fluid and equipped with an elastic cushion under the influence of an external magnetic field. This invention can solve the problem that traditional magnetic fluid dampers cannot be applied to vibration environments above 100Hz. However, this damper contains only one sphere, and collision damping only occurs between the copper sphere and the cushion inside the cavity, resulting in very limited damping force. As the vibration frequency increases, the damping force of this damper will be insufficient. Furthermore, the sphere in this damper is only constrained by the levitation force of the magnetic fluid, resulting in a fixed suspension height and no possibility of adjustment according to vibration conditions.

[0004] Therefore, there is an urgent need to redesign and improve the structure of particle collision damping so that it can be applied not only in high-frequency vibration applications, but also in low- and mid-frequency vibration applications, and will not fail in weightless environments. Summary of the Invention

[0005] The technical problem this invention aims to solve is that existing particle collision dampers are ineffective for vibrations below 1000Hz due to the high friction between solid particles, and are even less suitable for low-to-medium frequency vibrations below 100Hz. Furthermore, in a weightless environment, the particles will drift freely, unable to generate effective collisions, and thus face failure. This invention provides a particle collision damper based on the suspension characteristics of magnetic liquids. Utilizing the levitation force generated by the magnetic liquid under a non-uniform magnetic field, multiple spheres are suspended inside a shell, reducing the solid friction between the spheres and making them highly sensitive to inertial forces. When vibration occurs, the spheres move and collide within the magnetic liquid, generating both liquid viscous damping and particle collision damping. This provides excellent vibration reduction performance for both low-frequency vibrations of only a few hertz and high-frequency vibrations of thousands of hertz. In addition, filling the spheres with a magnetic filler material allows the spheres to be subjected to the combined effects of magnetic liquid levitation force and magnetic attraction, preventing them from drifting freely and failing even in a weightless environment.

[0006] The technical solution adopted by this invention to solve its technical problem is:

[0007] The damper includes: a sphere, a magnetic fluid, a bottom magnetic source, a shell, a side magnetic source one, a top magnetic source and a side magnetic source two, a spherical shell and a filling material.

[0008] The filling material is inserted into the spherical shell to form a sphere.

[0009] The sphere is inserted into a shell, which is then filled with a magnetic fluid. A bottom magnetic source, a first side magnetic source, a top magnetic source, and a second side magnetic source are fixedly installed on the outer wall of the shell to form an external magnetic field source.

[0010] The spherical shell is made of non-magnetic metal, and the filling material is made of magnetic material. The filling material accounts for 0% to 90% of the sphere's volume, and makes the sphere's equivalent density greater than the density of the magnetic liquid. That is, the sphere can be a solid non-magnetic metal, a hollow non-magnetic metal, or a composite sphere composed of a non-magnetic metal shell and a magnetic filling material. The filling material can be selected as needed, including electrical pure iron, soft magnetic materials, magnetic liquids, magnetic powder, or even mixtures of these materials.

[0011] The outer diameter of the spheres is greater than or equal to 1 mm, and the volumetric filling rate in the shell is 10-90%. Depending on the external vibration conditions, their dimensions may be the same or different. The number of spheres must be greater than one, that is, at least two, to ensure that the spheres will collide with each other after vibration occurs, generating particle collision damping.

[0012] The volumetric filling rate of the magnetic fluid in the shell ranges from 10% to 90%. Depending on the external vibration conditions, the volume of the magnetic fluid and the sphere can completely fill the entire inner cavity of the shell, or it can partially fill the inner cavity of the shell.

[0013] The shell is made of a non-magnetic metal, such as copper or non-magnetic steel. The shell can be cylindrical, cuboid, or cube. The bottom magnetic source, side magnetic source one, top magnetic source, and side magnetic source two are all composed of permanent magnets. They can be composed of multiple permanent magnets or a single permanent magnet. Furthermore, depending on the specific vibration and application environment, various methods can be used, such as using only the bottom magnetic source, a combination of the bottom magnetic source, side magnetic source one, and side magnetic source two, or a combination of the bottom and top magnetic sources. The external magnetic field source provides a non-uniform external magnetic field, generating a gradient magnetic levitation force within the magnetic liquid and a magnetic attraction force on the filling material inside the sphere. These two forces allow the sphere to be suspended at different positions within the magnetic liquid. The magnetic poles of the bottom magnetic source, side magnetic source one, top magnetic source, and side magnetic source two can be arranged arbitrarily; for example, all the magnetic poles on the side adjacent to the shell wall can be the same, or adjacent magnetic poles can be opposite. For example, the upper surface of the bottom magnetic source, the left side of the first side magnetic source, the right side of the second side magnetic source, and the lower surface of the top magnetic source are all N poles, or all of them are S poles. Alternatively, the upper surface of the bottom magnetic source and the lower surface of the top magnetic source may both have N poles, while the left side of the first side magnetic source and the right side of the second side magnetic source may both have S poles.

[0014] The advantages of this invention compared to existing technologies are as follows: (1) By utilizing the external magnetic fields provided by the bottom magnetic source, side magnetic source one, top magnetic source, and side magnetic source two, all spheres are suspended in the magnetic liquid, reducing the friction between the spheres. Moreover, the spheres vary in size and internal filling material, resulting in different suspension heights, making the spheres more sensitive and diverse to external vibrations. This allows the invention to be applied not only to vibrations with frequencies of several hundred or even thousands of hertz, but also to vibrations with frequencies below 100 Hz. (2) The spheres are composed of non-magnetic metal and magnetic filling material, which allows them to be subjected to both magnetic levitation force and magnetic attraction force in the magnetic liquid and external magnetic field. By changing the size of the spheres and the filling rate of the magnetic filling material, the suspension position of the spheres can be controlled, thereby adjusting the probability of collisions between the spheres and the magnitude of collision damping. In addition, it is no longer restricted by gravity and can still be used in a weightless environment; (3) The equivalent density of the sphere is greater than that of the magnetic liquid. When external vibration occurs, the sphere and the magnetic liquid will move relative to each other, thereby driving the magnetic liquid to flow and generating additional magnetic liquid damping to consume vibration energy, which is very beneficial for low-frequency vibrations within 10Hz. Attached Figure Description

[0015] Figure 1 Schematic diagram of a particle collision damper based on the magnetic liquid suspension properties.

[0016] Figure 2 A schematic diagram of the structure of a sphere;

[0017] Figure 3 A schematic diagram of a particle collision damper based on the magnetic fluid suspension properties when the sphere is solid;

[0018] Figure 4 A schematic diagram of a particle collision damper based on the magnetic liquid suspension characteristics, with only the bottom magnetic source installed;

[0019] Figure 5 A schematic diagram of a particle collision damper based on the magnetic liquid suspension characteristics, consisting of a bottom magnetic source and a top magnetic source.

[0020] Figure 6 A schematic diagram of a particle collision damper based on the magnetic liquid suspension properties without a top magnetic source.

[0021] Figure 7 Schematic diagram of a particle collision damper based on the magnetic fluid suspension properties where the magnetic fluid does not completely fill the shell;

[0022] In the diagram: 1. Sphere; 2. Magnetic liquid; 3. Bottom magnetic source; 4. Shell; 5. Side magnetic source one; 6. Top magnetic source; 7. Side magnetic source two; 8. Spherical shell; and 9. Filling material. Detailed Implementation

[0023] The present invention will be further described with reference to the accompanying drawings as specific embodiments:

[0024] Particle collision dampers based on the magnetic fluid suspension properties, such as Figures 1-5 The damper includes: a sphere 1, a magnetic fluid 2, a bottom magnetic source 3, a shell 4, a side magnetic source 5, a top magnetic source 6, a side magnetic source 2 7, a spherical shell 8, and a filling material 9.

[0025] The filling material 9 is inserted into the spherical shell 8 to form a sphere 1. The spherical shell 8 is made of a non-magnetic metal, and the filling material 9 is made of a magnetic material. The filling material 9 can be selected from electrical pure iron, soft magnetic materials, magnetic liquid 2, and magnetic powder, or even a mixture of these materials, as needed. The filling material 9 accounts for 0% to 90% of the volume of the sphere 1, and makes the equivalent density of the sphere 1 greater than the density of the magnetic liquid 2. The spherical shell 8 can be segmented or perforated, and then sealed by welding or gluing after the filling material 9 is inserted. If the filling material 9 accounts for 0% of the volume of the sphere 1, the sphere 1 can be designed as a hollow non-magnetic metal shell or a solid non-magnetic metal sphere, depending on the suspension height and external vibration conditions.

[0026] The sphere 1 is inserted into the housing 4, and the housing 4 is filled with magnetic fluid 2. The housing 4 can be sealed by end caps or welding. The outer diameter of the sphere 1 is greater than or equal to 1 mm, and its volume filling rate in the housing 4 is 10-90%. The number of spheres 1 must be greater than one, i.e., at least two. The total mass of all spheres 1 must not be less than 10% of the concentrated mass of the object being damped. All spheres 1 can be the same size or different sizes. Larger spheres 1 are more sensitive to low-frequency vibrations, while smaller spheres 1 have greater damping force for high-frequency vibrations; the selection should be based on the specific vibration conditions. If the vibration frequency is relatively uniform, and the vibration frequency of the object being damped is only tens of hertz, the number of spheres 1 should be reduced, preferably to less than 10, while the size of spheres 1 should be increased. If the vibration frequency is relatively uniform and the frequency is greater than 100 Hz, the number of spheres 1 should be increased as the vibration frequency increases, while the size of spheres 1 should be decreased. If the vibration frequency range of the object being damped is large, large-sized spheres 1 and small-sized spheres 1 can be mixed in a certain proportion according to their volume fraction.

[0027] The volumetric filling rate of magnetic fluid 2 in shell 4 ranges from 10% to 90%. The volume of magnetic fluid 2 and sphere 1 can completely fill the entire cavity of shell 4, or it can partially fill it, depending on external vibration conditions. Therefore, shell 4 contains two substances: sphere 1 and magnetic fluid 2, or possibly three substances: sphere 1, air, and magnetic fluid 2. For example, when the filling rate of sphere 1 in shell 4 is 20%, and the filling rate of magnetic fluid 2 in shell 4 is 70%, then 10% of the volume inside shell 4 is air.

[0028] A bottom magnetic source 3, a first side magnetic source 5, a top magnetic source 6, and a second side magnetic source 7 are fixedly installed on the outer wall of the housing 4 to form an external magnetic field source. These can be achieved through adhesive bonding or threaded connections. The bottom magnetic source 3, the first side magnetic source 5, the top magnetic source 6, and the second side magnetic source 7 are all composed of permanent magnets, and neodymium iron boron or samarium cobalt permanent magnet materials can be selected depending on the temperature environment. Multiple permanent magnets can be combined, or a single permanent magnet can be used. Furthermore, depending on the specific vibration and application environment, various methods can be employed, such as using only the bottom magnetic source 3, a combination of the bottom magnetic source 3, the first side magnetic source 5, and the second side magnetic source 7, or a combination of the bottom magnetic source 3 and the top magnetic source 6. The external magnetic field source provides a non-uniform external magnetic field, generating a gradient magnetic levitation force within the magnetic liquid and a magnetic attraction force on the filling material inside the sphere. These two forces allow the sphere 1 to be suspended at different positions within the magnetic liquid 2. The external magnetic field source can also be designed with magnetic conductive metal, or a sufficiently strong gradient magnetic field can be generated inside the shell 4 by arranging permanent magnets with different magnetization directions.

[0029] The shell 4 is made of a non-magnetic metal, such as copper or non-magnetic steel. The shape of the shell 4 can be cylindrical, cuboid, or cube.

[0030] After vibration occurs, because the equivalent density of sphere 1 is greater than the density of magnetic fluid 2, all spheres 1 will move inside magnetic fluid 2 under the influence of its viscosity and inertial force, creating a displacement difference with the shell 4, and converging in the opposite direction of vibration. During this process, all spheres 1 not only generate viscous damping force with magnetic fluid 2, but also collide with each other and even with the wall of shell 4, generating particle collision damping. The effect of the viscous damping force of the magnetic fluid weakens with increasing vibration frequency, while the effect of particle collision damping increases with increasing vibration frequency. Therefore, at low frequencies, such as below 10Hz, energy consumption is mainly due to the fluid friction between magnetic fluid 2 and spheres 1. At vibrations below 100Hz, some collisions will occur between spheres 1, generating particle collision damping. At this time, the energy consumption of the damper is mainly due to the fluid friction between magnetic fluid 2 and spheres 1, and some particle collision friction between spheres 1. At frequencies of several hundred or even thousands of hertz, the fluid friction between the magnetic fluid 2 and the sphere 1 is very small, but the collisions between the spheres 1 will be very frequent, and the energy consumption will mainly be due to the damping of particle collisions between the spheres 1.

[0031] The magnetic fluid 2 should be selected from kerosene-based, oil-based, and ester-based magnetic fluids, and its viscosity should not exceed 500 mPa·s. It should not be replaced by similar magnetic fluids, such as magnetorheological fluids.

[0032] The above is merely an example of the implementation of the present invention and is not intended to limit the present invention. For those skilled in the art, the particle collision damper based on the magnetic liquid suspension characteristics can be modified according to the engineering situation, including but not limited to the size of the damper, the volume ratio of each part of the sphere, the shell shape, the material selection, the installation position, etc., to adapt to the corresponding engineering.

Claims

1. A particle impact damper based on the suspension properties of magnetic liquids, characterized in that: The damper comprises a ball (1), a magnetic liquid (2), a bottom magnetic source (3), a shell (4), a side magnetic source one (5), a top magnetic source (6), a side magnetic source two (7), a ball shell (8) and a filling material (9); The filling material (9) is filled into the ball shell (8) to form the ball (1); The ball (1) is filled into the shell (4) to form a particle collision damping; the magnetic liquid (2) is filled into the shell (4); the bottom magnetic source (3), the side magnetic source one (5), the top magnetic source (6) and the side magnetic source two (7) are fixedly installed on the shell wall surface of the shell (4) to form an external magnetic field source; the filling material (9) is a magnetic material, and the equivalent density of the ball (1) is greater than the density of the magnetic liquid (2); the number of the ball (1) is greater than 1.

2. The particle collision damper based on the magnetic liquid suspension characteristics according to claim 1, characterized by: The ball shell (8) is made of a non-magnetic metal; the volume proportion of the filling material (9) in the ball (1) is 0% to 90%.

3. The particle collision damper based on the magnetic liquid suspension characteristics according to claim 1, characterized by: The shell (4) is made of a non-magnetic metal, and the bottom magnetic source (3), the side magnetic source one (5), the top magnetic source (6) and the side magnetic source two (7) are all made of permanent magnets.

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