Multistage variable stiffness damper

Abstract

According to the multi-stage variable-stiffness damper, the piston is arranged in the first mounting cylinder, the first mounting cylinder is nested in the second mounting cylinder, and a multi-stage vibration reduction structure is formed; the magneto-rheological shear thickening fluid (MRSTF) is contained in the first mounting cylinder, and the magneto-rheological grease (MRG) is wrapped between the outer wall of the first mounting cylinder and the magnet exciting coil of the second mounting cylinder. When an external load acts on the damper structure, the magneto-rheological shear thickening fluid (MRSTF) of the first mounting cylinder provides enough damping force to dissipate energy and weaken the response peak value of the structure, and meanwhile, the magneto-rheological grease (MRG) provides magnetic control rigidity on one hand and inhibits radial vibration on the other hand, so that the multi-stage variable-rigidity variable-damping function of the damper under two working conditions is achieved; the device is simple in structure, does not need too many complicated processes, and is easy to realize.

Description

Technical Field

[0001] The invention relates to a multi-stage variable stiffness damper, belonging to the technical field of intelligent material vibration control dampers. Background Art

[0002] With the rapid development of economy and the continuous increase of traffic flow, the safety and durability of bridges as important transportation infrastructure have received more and more attention. Dampers, as an effective bridge shock absorption device, can reduce bridge vibration caused by traffic loads, earthquakes, etc., and ensure the safety and service life of bridges. At the same time, the development of new intelligent materials and new technologies has provided new ideas for the research and application of dampers, making the performance of dampers more diversified and efficient.

[0003] Magnetorheological damper is an important branch of smart material damper. At present, most of the research and development of magnetorheological dampers focuses on realizing energy dissipation function with a single material, and mainly realizes active control through magnetorheological shear thickening fluid or electrorheological fluid and structural design. It uses the change of viscosity of magnetorheological (electro)rheological fluid under the action of magnetic (electric) field to realize the regulation of damping force, which can change from liquid state to solid-like state, and the yield strength of the material will change with the magnitude of the applied magnetic (electric) field strength. The patent with authorization announcement number CN118188747B provides a damper with a multi-stage magnetorheological shear thickening fluid channel piston. By setting multiple curved magnetorheological passages in the piston, the damping length is increased, thereby improving the energy dissipation effect of the damper. The patent with authorization announcement number CN108953466B invented a damper based on electrorheological fluid. By setting multiple positive and negative plates inside the cavity of the damper, the flow direction of the electrorheological fluid is controlled after applying a high-voltage DC electric field, thereby realizing active control vibration reduction. Although the above patent results can improve the energy consumption effect of the damper, on the one hand, it requires continuous supply of energy from the outside. Once a power outage occurs, the damper will lose its original mechanical properties; on the other hand, although a single magnetorheological (electro) rheological fluid can achieve variable damping control, the stiffness requirements of the damper cannot be guaranteed. Summary of the invention

[0004] The purpose of the present invention is to provide a multi-stage variable stiffness damper. Through ingenious structural design, the damper can increase the buffering time when subjected to external loads, thereby better exerting the energy dissipation effect.

[0005] In order to achieve the above objectives / solve the above technical problems, the present invention is implemented by adopting the following technical solutions.

[0006] In a first aspect, the present invention provides a multi-stage variable stiffness damper, comprising: a piston, a first mounting cylinder and a second mounting cylinder; the piston is arranged inside the first mounting cylinder and slides axially, the first mounting cylinder is inserted into one end of the second mounting cylinder, and the other end of the second mounting cylinder is connected to an elastic component, the first mounting cylinder and the second mounting cylinder are arranged coaxially, the first mounting cylinder is filled with a magnetorheological shear thickening fluid, an annular groove is provided on the outer wall of the piston, and a first excitation coil is arranged in the annular groove.

[0007] Furthermore, a magnetorheological grease layer and a second excitation coil are coaxially arranged in sequence from inside to outside in the gap between the first mounting tube and the second mounting tube, and the magnetorheological grease layer includes: an annular steel ring groove and magnetorheological grease, and the magnetorheological grease is filled in the annular steel ring groove.

[0008] Furthermore, it also includes: a piston rod, which penetrates the top cover plate of the first mounting cylinder from top to bottom, and one end of the piston rod extends into the cylinder body of the first mounting cylinder and is connected to the piston. The piston rod and the top cover plate are coaxially arranged, and the free end of the piston rod is outside the first mounting cylinder, which is used to transmit external force and ensure that the piston moves in a straight line.

[0009] Furthermore, an opening is arranged at the top end of the second installation tube, the opening is connected to the end cover, and the bottom end of the second installation tube is connected to the base.

[0010] Furthermore, the piston is made of soft magnetic material with high magnetic induction strength to respond quickly and generate a strong internal magnetic field.

[0011] Furthermore, the thickness of the magnetorheological grease is set to 6-10 mm, and under the action of the magnetic field, it is used to provide a certain magnetic flux stiffness to resist external vibration loads.

[0012] Furthermore, a sealing ring is provided between the first installation cylinder body and the top cover plate to seal the magnetorheological shear thickening fluid inside the first installation cylinder body.

[0013] Furthermore, a sealing ring is provided between the second mounting cylinder body and the end cover for sealing the magnetorheological grease and isolating vibration.

[0014] Furthermore, the height of the first mounting tube is greater than that of the second mounting tube, which is used to ensure the multi-stage vibration reduction structure of the damper device, and the plug-in portion of the first mounting tube and the second mounting tube is sealed with a sealing ring to reduce friction between the components.

[0015] Compared with the prior art, the present invention has the following beneficial effects: the present invention realizes active and passive combined control by pouring magnetorheological shear thickening fluid into the first installation cylinder. Under normal working conditions, the magnetorheological effect of the magnetorheological shear thickening fluid plays a major role, and the iron particles form a magnetic chain structure under the action of the magnetic field to provide damping force; in the case of power failure, the rate effect of the magnetorheological shear thickening fluid plays a role, and under the action of impact load, the material changes from a fluid state to a solid-like state, thereby providing damping force and expanding the application range of the magnetorheological damper.

[0016] The multi-stage variable damping and variable stiffness damper provided by the present invention is used for vibration reduction of bridge structures, and utilizes the stiffness and damping of different magnetorheological materials, that is, the magnetorheological shear thickening fluid is mainly used as the core component of the variable damping vibration reduction unit, and the magnetorheological grease layer is used as the main component of the variable stiffness vibration reduction unit. When subjected to external loads, the impact energy is consumed by the magnetorheological shear thickening fluid, and at the same time, the magnetorheological grease layer utilizes its magnetically controlled stiffness to achieve variable frequency vibration isolation. The coordinated work of the two can enable the damper to achieve vibration attenuation of external loads within a wider frequency range.

[0017] The present invention uses an ingenious structural design to nest the first mounting cylinder in the second mounting cylinder, and the piston is arranged in the first mounting cylinder so that the energy consumption of the damper is divided into multiple stages, realizing multi-level energy consumption; at the same time, magnetorheological grease is arranged between the first mounting cylinder and the second mounting cylinder, which can effectively exert the lateral vibration isolation of the damper. That is, the damper provided by the present invention can not only exert multi-level damping and stiffness control in the axial direction, but also can realize damping energy consumption in the radial direction, and can take into account both working conditions. Compared with the traditional damper, it has a larger displacement stroke and better energy consumption effect. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 It is a schematic diagram of the cross-sectional structure of the multi-stage variable stiffness damper of the present invention; Figure 2 It is a schematic diagram of the overall appearance structure of the multi-stage variable stiffness damper of the present invention; Wherein: 1. piston; 2. cover plate; 3. outer wall of first mounting tube; 4. inner wall of first mounting tube; 5. end cover; 6. piston rod; 7. first excitation coil; 8. magnetorheological shear thickening liquid; 9. magnetorheological grease layer; 10. second excitation coil; 11. elastic component; 13. inner wall of second mounting tube; 14. bottom of second mounting tube; 15. base; 16. bolt mouth; 17. first mounting tube; 18. second mounting tube. DETAILED DESCRIPTION

[0019] The technical solution of the present invention is described in detail below through the accompanying drawings and specific embodiments. It should be understood that the embodiments of the present invention and the specific features in the embodiments are detailed descriptions of the technical solution of the present invention, rather than limitations on the technical solution of the present invention. The embodiments of the present invention and the technical features in the embodiments may be combined with each other unless there is a conflict.

[0020] The term "and / or" is only a description of the association relationship between related objects, indicating that there can be three relationships. For example, A and / or B can mean: A exists alone, A and B exist at the same time, and B exists alone. In addition, the character " / " generally indicates that the related objects are in an "or" relationship. Example

[0021] like Figure 1~2 An embodiment shown in the figure provides a multi-stage variable stiffness damper, comprising: a piston 1, a piston rod 6, a first mounting cylinder 17 and a second mounting cylinder 18; the piston 1 is arranged inside the first mounting cylinder 17 and slides axially, the first mounting cylinder 17 is inserted into one end of the second mounting cylinder 18, and the other end of the second mounting cylinder 18 is connected to the elastic component 11, the first mounting cylinder 17 and the second mounting cylinder 18 are coaxially arranged, the first mounting cylinder 17 is filled with a magnetorheological shear thickening fluid 8 (MRSTF), an annular groove is provided on the outer wall of the piston 1, a first excitation coil 7 is arranged in the annular groove, the piston rod 6 passes through the top cover plate 2 of the first mounting cylinder 17 from top to bottom, one end of the piston rod 6 extending into the cylinder body of the first mounting cylinder 17 is connected to the piston 1, the piston rod 6 and the top cover plate 2 are coaxially arranged, the piston 1 adopts a soft magnetic material with high magnetic induction strength, the elastic component 11 adopts a limit spring, and there is a certain gap between the piston 1 and the inner wall 4 of the first mounting cylinder.

[0022] A magnetorheological grease layer 9 and a second excitation coil 10 are coaxially arranged in the gap between the outer wall 3 of the first mounting tube and the inner wall 13 of the second mounting tube from the inside to the outside. The magnetorheological grease layer 9 includes: an annular steel ring groove and magnetorheological grease. The magnetorheological grease is filled in the annular steel ring groove. The thickness of the magnetorheological grease is set to 10 mm.

[0023] An opening is arranged at the top end of the second mounting tube 18, and the opening is connected to the end cover 5; the bottom 14 of the second mounting tube is connected to the base 15; bolt openings 16 are evenly arranged on the base 15; a sealing ring is arranged between the body of the first mounting tube 17 and the top cover plate 2; a sealing ring is arranged between the body of the second mounting tube 18 and the end cover 5; the height of the first mounting tube 17 is greater than the height of the second mounting tube 18, and the plug-in portion between the first mounting tube 17 and the second mounting tube 18 is sealed with a sealing ring.

[0024] The first excitation coil 7 and the second excitation coil 10 in this embodiment require external power supply to provide a magnetic field for the magnetorheological shear thickening fluid 8 and the magnetorheological fat layer 9, so that the magnetorheological shear thickening fluid 8 and the magnetorheological fat layer 9 generate a magnetic chain structure to provide a certain damping force and magnetic control stiffness.

[0025] When this embodiment is subjected to external load, three stages of vibration reduction will be initiated: linear motion of the piston 6 in the first mounting cylinder 17, shear sliding of the first mounting cylinder 17 along the inner wall 13 of the second mounting cylinder, and reciprocating motion formed by the compression limit spring of the first mounting cylinder 17.

[0026] When the damper is subjected to an impact load, the first stage of vibration reduction is started: the load first acts on the piston rod 6, and at this time the excitation coil 7 outside the piston 1 provides a magnetic field to the magnetorheological shear thickening fluid in the first mounting cylinder 17, so that the magnetic particles in the magnetorheological shear thickening fluid 8 form a chain structure. At the same time, the sudden impact force stimulates the shear thickening effect of the magnetorheological shear thickening fluid 8, and multiple clusters are formed inside the system. The magnetorheological shear thickening fluid 8 also changes from a fluid state to a solid-like state, thereby providing damping force and consuming most of the impact energy.

[0027] When the piston 1 is pushed to the bottom of the first mounting cylinder 17, the second stage of vibration reduction is started: the first mounting cylinder 17 will continue to move forward in the second mounting cylinder 18. At this time, the second mounting cylinder excitation coil 10 provides a magnetic field to the magnetorheological grease layer 9. The magnetic particles in the magnetorheological grease layer 9 form a magnetic chain structure to provide a certain magnetic control stiffness. The magnetorheological grease layer 9 is arranged between the first mounting cylinder 17 and the second mounting cylinder 18, which can effectively play a lateral vibration isolation role.

[0028] The first mounting tube 17 continues to compress the limit spring 11 along the inner wall 13 of the second mounting tube, and the third stage of vibration reduction is started at this time. The limit spring 11 provides a certain stiffness and provides elastic force to the first mounting tube 17, so that the first mounting tube 17 performs reciprocating motion, thereby realizing energy consumption vibration reduction within a certain period of time.

[0029] The present embodiment provides a multi-stage variable stiffness damper device based on magnetorheological shear thickening material (MRSTF-G). Generally, an external power supply is required to achieve multi-stage vibration reduction. After the first excitation coil 7 and the second excitation coil 10 are energized, a magnetic field perpendicular to the flow direction of the magnetorheological material is generated, so that the magnetic particles in the magnetorheological shear thickening liquid 8 and the magnetorheological lipid layer 9 generate a magnetic chain structure, provide damping force, and achieve the effect of vibration reduction.

[0030] In addition, in the case of power failure, the magnetorheological shear thickening fluid (MRSTF) in the inner cylinder can still provide a certain damping force due to its shear thickening effect, and the magnetorheological grease (MRG) can be used as a viscoelastic spacer to buffer lateral vibration. In summary, whether the device is powered on normally or without power supply, the damper provided by the present invention can play a vibration reduction effect and has a wide range of application scenarios.

[0031] The semi-active graded controllable variable damping and variable stiffness damper provided by the present invention is used to protect infrastructure such as bridges. The semi-active control does not completely rely on the damping characteristics of the material itself, nor does it completely rely on external energy input for active control; the graded control mainly allows the damper to increase the buffering time when subjected to external loads, thereby better exerting the energy dissipation effect; the variable damping and variable stiffness refers to the material providing variable damping force and stiffness with the size of the magnetic field. Therefore, the damper needs to have both a variable damping energy dissipation unit and a variable stiffness vibration reduction unit, and the two cooperate with each other so that the damper can effectively provide stiffness and damping force when subjected to external impact loads.

[0032] The embodiments of the present invention are described above in conjunction with the accompanying drawings, but the present invention is not limited to the above-mentioned specific implementation methods. The above-mentioned specific implementation methods are merely illustrative and not restrictive. Under the enlightenment of the present invention, ordinary technicians in this field can also make many forms without departing from the scope of protection of the purpose of the present invention and the claims, which all fall within the protection of the present invention.

Claims

1. A multi-stage variable stiffness damper, characterized in that: include: A piston (1), a first mounting cylinder (17) and a second mounting cylinder (18); the piston (1) is arranged inside the first mounting cylinder (17) and slides axially; the first mounting cylinder (17) is inserted into one end of the second mounting cylinder (18), and the other end of the second mounting cylinder (18) is connected to an elastic component (11); the first mounting cylinder (17) and the second mounting cylinder (18) are arranged coaxially; the first mounting cylinder (17) is filled with a magnetorheological shear thickening fluid (8); an annular groove is provided on the outer wall of the piston (1), and a first excitation coil (7) is arranged in the annular groove.

2. The multi-stage variable stiffness damper according to claim 1, characterized in that: A magnetorheological grease layer (9) and a second excitation coil (10) are coaxially arranged in sequence from the inside to the outside of the gap between the first mounting tube (17) and the second mounting tube (18), wherein the magnetorheological grease layer (9) comprises an annular steel ring groove and magnetorheological grease, and the magnetorheological grease is filled in the annular steel ring groove.

3. The multi-stage variable stiffness damper according to claim 1, characterized in that: Also includes: A piston rod (6), the piston rod (6) passing through the top cover plate (2) of the first mounting cylinder (17) from top to bottom, one end of the piston rod (6) extending into the cylinder body of the first mounting cylinder (17) is connected to the piston (1), and the piston rod (6) and the top cover plate (2) are coaxially arranged.

4. The multi-stage variable stiffness damper according to claim 1, characterized in that: The second mounting tube (18) has an opening at the top end, the opening is connected to the end cover (5), and the second mounting tube (18) has a bottom end connected to the base (15).

5. The multi-stage variable stiffness damper according to claim 1, characterized in that: The piston is made of soft magnetic material with high magnetic induction strength.

6. The multi-stage variable stiffness damper according to claim 2, characterized in that: The thickness of the magnetorheological grease is set to 6-10 mm.

7. The multi-stage variable stiffness damper according to claim 3, characterized in that: A sealing ring is provided between the body of the first mounting tube (17) and the top cover plate (2).

8. The multi-stage variable stiffness damper according to claim 4, characterized in that: A sealing ring is provided between the body of the second mounting cylinder (18) and the end cover (5).

9. The multi-stage variable stiffness damper according to claim 1, characterized in that: The height of the first installation tube (17) is greater than the height of the second installation tube (18), and the plug-in portion between the first installation tube (17) and the second installation tube (18) is sealed with a sealing ring.

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