A negative stiffness vibration dual-control damper with variable mass and variable damping

Abstract

This invention belongs to the field of building vibration reduction / vibration technology, and provides a negative stiffness vibration dual-control damper with variable mass and variable damping characteristics. It includes a piston with a piston rod fixedly connected to one side; a viscous damper body including a piston chamber assembly filled with a viscous liquid, the piston being slidably disposed within the piston chamber assembly, and a first flow element on the piston chamber assembly; an inertial mass body including a second outer sleeve fixedly connected to one end of the piston chamber assembly, the piston rod slidably passing through the second outer sleeve, two sets of flywheel assemblies on the piston rod, and a first and second driving element disposed within the second outer sleeve; and a negative stiffness body including a first outer sleeve, with the piston rod and the first outer sleeve connected by an elastic element. This invention can provide excellent vibration reduction / vibration performance under conditions of large and small deformations.

Description

Technical Field

[0001] This invention belongs to the field of building vibration reduction / vibration technology, and particularly relates to a negative stiffness vibration dual-control damper with variable mass and variable damping characteristics. Background Technology

[0002] With the continuous development of society and the economy, the height and span of building and bridge structures have increased significantly, leading to frequent structural vibration events, such as the SEG Plaza vibration in 2021, the Techno Mart 21 building vibration in 2011, and the Oakland Bay Bridge vibration in California in 2006. Therefore, structural vibration has become a focus of public attention. Ensuring building safety while meeting comfort requirements is a challenging problem. Current technical difficulties lie in how to further achieve multi-stage vibration control, achieving dual control of displacement and acceleration, and simultaneously reducing flywheel mass when the inertia-capacity ratio is constant, or effectively increasing the inertia-capacity ratio when the mass is constant, to achieve better vibration reduction / shock absorption. Summary of the Invention

[0003] The purpose of this invention is to provide a negative stiffness vibration dual-control damper with variable mass and variable damping characteristics to solve the above problems, realize multi-stage vibration control, achieve the effect of dual control of displacement and acceleration, and by introducing a negative stiffness mechanism, the flywheel mass can be reduced when the inertia-capacity ratio is constant, or the inertia-capacity ratio can be effectively increased when the mass is constant. Moreover, by using a rack and pinion combination instead of a ball screw, the cost is further reduced.

[0004] To achieve the above objectives, the present invention provides the following solution: a negative stiffness vibration dual-controlled damper with variable mass and variable damping characteristics, comprising:

[0005] A piston, on one side of which a piston rod is fixedly connected;

[0006] The main body of the viscous damper includes a piston chamber assembly, which is filled with a viscous liquid. The piston is slidably disposed within the piston chamber assembly. A first flow element is provided on the piston chamber assembly. During small displacement vibration, the piston is positioned between the inlet and outlet ends of the first flow element.

[0007] The inertial mass body includes a second outer sleeve fixedly connected to one end of the piston chamber assembly. The piston rod slides through the second outer sleeve. Two sets of flywheel assemblies are provided on the piston rod. A first driving member and a second driving member are provided inside the second outer sleeve. During small displacement vibration, one of the flywheel assemblies is connected to the first driving member. During large displacement vibration, the two sets of flywheel assemblies are connected to the first driving member and the second driving member, respectively.

[0008] The negative stiffness body includes a first outer sleeve, the end of the piston rod away from the piston is located inside the first outer sleeve, and the piston rod and the first outer sleeve are connected by an elastic element.

[0009] Preferably, the piston chamber assembly includes a third outer sleeve and an inner sleeve disposed inside the third outer sleeve, and the first flow member is disposed between the inner sleeve and the third outer sleeve.

[0010] Preferably, the first flow element includes a sealing material filled between the inner sleeve and the third outer sleeve. The sealing material is used to create a cavity between the outer wall of the inner sleeve and the inner wall of the third outer sleeve. A plurality of second damping holes 132 are provided on the side wall of the inner sleeve. The plurality of second damping holes 132 are arranged in two rows along the axial direction of the inner sleeve 12. The two rows of second damping holes are connected through the cavity. During small displacement vibration, the piston is located between the two rows of second damping holes. During large displacement vibration, the piston is located outside the two rows of second damping holes.

[0011] Preferably, the piston is further provided with a plurality of first damping holes, which are used to connect the viscous liquid on both sides of the piston.

[0012] Preferably, the flywheel assembly includes a flywheel rotatably connected to the piston rod and a gear drive fixedly connected to the piston rod. The output end of the gear drive is drivenly connected to the flywheel, and the input end of the gear drive is drivenly connected to the first drive or the second drive.

[0013] Preferably, the gear drive component includes a fixed plate fixedly connected to the piston rod, a first matching gear and a second matching gear rotatably connected to the fixed plate, the first matching gear and the second matching gear meshing with each other, the first matching gear being drively connected to the first drive component or the second drive component, a second transmission gear being fixedly connected to the second matching gear on the same axis, a first transmission gear being rotatably connected to the piston rod, the first transmission gear being fixedly connected to the flywheel on the same axis, and the first transmission gear meshing with the second transmission gear.

[0014] Preferably, the first driving component includes a long rack fixedly connected to the inner wall of the second outer sleeve, the long rack being arranged parallel to the piston rod, and a first matching gear meshing with the long rack;

[0015] The second driving component includes a first short rack and a second short rack fixedly mounted on the inner wall of the second outer sleeve. The first short rack and the second short rack are parallel to the piston rod, and the first short rack and the second short rack are arranged along the same straight line. Another first matching gear is arranged correspondingly to the first short rack and the second short rack.

[0016] Preferably, the elastic element includes a plurality of preloaded springs, one end of which is fixedly connected to the inner wall of the first outer sleeve, and the other end of which is fixedly connected to the end of the piston rod away from the piston.

[0017] Preferably, a second earring is fixedly connected to the end of the first outer sleeve away from the second outer sleeve.

[0018] Preferably, the first earring is fixedly connected to the end of the third outer sleeve away from the second outer sleeve.

[0019] Compared with the prior art, the present invention has the following advantages and technical effects:

[0020] 1. By using a variable-mass inertial body and a variable-damping viscous body, different masses and damping are provided under different displacement vibrations, which can better meet the vibration reduction / energy dissipation requirements under different displacements of different sizes. That is, under small displacements, only a single flywheel rotates, and when the displacement increases further, it transforms into two flywheels working simultaneously, realizing multi-stage vibration control, achieving the purpose of dual control of displacement and acceleration, and improving the overall safety and comfort of the building.

[0021] 2. By introducing a negative stiffness mechanism, the inertia-to-volume ratio can be effectively increased under a given mass, thereby maximizing the vibration reduction / shock absorption effect of the device within a certain volume.

[0022] 3. By changing the design parameters of the flywheel assembly and the first flow component in the inertial mass body, different vibration reduction / vibration requirements of the structure can be met. At the same time, the compression of the elastic component can be adjusted according to the actual situation to adapt to the requirements of the building environment.

[0023] 4. The present invention uses a gear and rack combination instead of a ball screw, and introduces a negative stiffness mechanism. The design of reducing the flywheel mass under a certain inertia-capacity ratio can further reduce the cost and improve the overall cost performance of the device. Attached Figure Description

[0024] 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 introduced 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.

[0025] Figure 1 This is a schematic diagram of the overall damper of the present invention;

[0026] Figure 2 This is an exploded view of the damper structure of the present invention;

[0027] Figure 3 This is a schematic diagram of the flywheel assembly of the present invention;

[0028] Figure 4 This is an exploded view of the piston chamber assembly of the present invention;

[0029] Figure 5 This is a schematic diagram of the negative stiffness main body of the present invention;

[0030] Figure 6 This is a schematic diagram of the piston of the present invention;

[0031] Among them, 1. Second earring; 2. Preload spring; 3. First outer sleeve; 4. Second outer sleeve; 5. Flywheel; 9. Third outer sleeve; 10. Piston rod; 11. Piston; 12. Inner sleeve; 14. Sealing material; 15. First earring; 16. Fixing plate; 61. First short rack; 62. Second short rack; 63. Long rack; 131. First damping hole; 132. Second damping hole; 71. First transmission gear; 72. Second transmission gear; 81. First matching gear; 82. Second matching gear. Detailed Implementation

[0032] 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.

[0033] 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.

[0034] Reference Figures 1-6 This invention provides a negative stiffness vibration dual-controlled damper with variable mass and variable damping characteristics, comprising:

[0035] Piston 11, with piston rod 10 fixedly connected to one side of piston 11;

[0036] The main body of the viscous damper includes a piston chamber assembly, which is filled with a viscous liquid. A piston 11 is slidably disposed in the piston chamber assembly. A first flow element is provided on the piston chamber assembly. During small displacement vibration, the piston 11 is located between the inlet and outlet ends of the first flow element.

[0037] The inertial mass body includes a second outer sleeve 4 fixedly connected to one end of the piston chamber assembly. The piston rod 10 slides through the second outer sleeve 4. Two sets of flywheel assemblies are provided on the piston rod 10. A first driving member and a second driving member are provided inside the second outer sleeve 4. During small displacement vibration, one flywheel assembly is connected to the first driving member. During large displacement vibration, the two sets of flywheel assemblies are connected to the first driving member and the second driving member, respectively.

[0038] The negative stiffness body includes a first outer sleeve 3, and the end of the piston rod 10 away from the piston 11 is located inside the first outer sleeve 3. The piston rod 10 and the first outer sleeve 3 are connected by an elastic element.

[0039] The main function of the viscous liquid is to generate resistance to the movement of piston 11; the main function of the first flow element is to allow the viscous liquid on one side of piston 11 to flow to the other side of piston 11 under the push of piston 11 during small displacement vibration, and to remove piston 11 from the port of the first flow element during large displacement vibration, so that the viscous liquid cannot flow through the first flow element, thus achieving a variable damping effect; the main function of the flywheel assembly is to convert vibration energy into rotational energy through the first or second drive element during damper vibration, and to achieve a vibration reduction effect through the generated rotational inertia; during small displacement vibration, the first drive element drives one flywheel assembly to rotate, and during large displacement vibration, the first and second drive elements drive two sets of flywheel assemblies to rotate simultaneously, thus achieving a variable mass effect; the main function of the elastic element is to provide negative stiffness. Overall, this invention can achieve multi-stage vibration control, achieving dual control of displacement and acceleration. By introducing a negative stiffness mechanism to reduce the flywheel mass, it can maximize the vibration reduction effect within a certain volume. Furthermore, the design of using a rack and pinion combination instead of a ball screw and introducing a negative stiffness mechanism to reduce the flywheel mass can further reduce costs and improve the overall cost-effectiveness of the device.

[0040] Further optimization of the design involves using silicone oil for the viscous liquid and a steel structure design for the piston rod 10 and piston 11.

[0041] In a further optimized design, the piston chamber assembly includes a third outer sleeve 9 and an inner sleeve 12 disposed inside the third outer sleeve 9, with a first flow element disposed between the inner sleeve 12 and the third outer sleeve 9.

[0042] In a further optimized design, the first flow element includes a sealing material 14 filled between the inner sleeve 12 and the third outer sleeve 9. The sealing material 14 is used to create a cavity between the outer wall of the inner sleeve 12 and the inner wall of the third outer sleeve 9. A plurality of second damping holes 132 are provided on the side wall of the inner sleeve 12. The plurality of second damping holes 132 are arranged in two rows along the axial direction of the inner sleeve 12. The two rows of second damping holes 132 are connected by a cavity. During small displacement vibration, the piston 11 is located between the two rows of second damping holes 132. During large displacement vibration, the piston 11 is located outside the two rows of second damping holes 132.

[0043] To further optimize the design, the sealing material 14 is made of rubber-based materials.

[0044] like Figure 1 and Figure 4 As shown, two rows of second damping holes 132 are circumferentially formed on the side wall of the inner sleeve 12. During small displacement vibration, the piston 11 moves only between the two rows of second damping holes 132. When the piston 11 moves to the left, the viscous liquid on the left side of the piston 11 is squeezed through several second damping holes 132 on the left side into the cavity formed between the inner sleeve 12, the third outer sleeve 9, and the sealing material 14, and flows into the space on the right side of the piston 11 through several second damping holes 132 on the right side. Similarly, when the piston 11 moves to the right, the viscous liquid on the right side of the piston 11 flows into the left side of the piston 11 through the second damping holes 132 on the right side and the second damping holes 132 on the left side in sequence. The resistance during the flow of the viscous liquid dampens the movement of the piston 11.

[0045] During large displacement vibration, when the piston 11 moves to the left beyond the second damping hole 132 on the left or to the right beyond the second damping hole 132 on the right, there is no longer any flow of viscous liquid between the two rows of second damping holes 132. Compared with the state during small displacement vibration, the damping of the piston 11 changes, thereby achieving the effect of variable damping.

[0046] In a further optimized design, the piston 11 is provided with several first damping holes 131, which are used to connect the viscous liquid on both sides of the piston 11.

[0047] like Figure 1 and Figure 6 As shown, the main function of the first damping orifice 131 is to allow the viscous liquid on both sides of the piston 11 to flow when the piston 11 moves, and to generate a damping effect through the flow of the viscous liquid in the first damping orifice 131.

[0048] In a further optimized design, the flywheel assembly includes a flywheel 5 rotatably connected to the piston rod 10 and a gear drive component fixedly connected to the piston rod 10. The output end of the gear drive component is connected to the flywheel 5 in a transmission connection, and the input end of the gear drive component is connected to the first drive component or the second drive component in a transmission connection.

[0049] The main function of flywheel 5 is to generate resistance to the operation of gear drive components through the rotational inertia generated during its own rotation, thereby damping the movement of piston rod 10.

[0050] In a further optimized design, the gear drive component includes a fixed plate 16 fixedly connected to the piston rod 10. A first matching gear 81 and a second matching gear 82 are rotatably connected to the fixed plate 16. The first matching gear 81 and the second matching gear 82 mesh with each other. The first matching gear 81 is connected to the first drive component or the second drive component for transmission. A second transmission gear 72 is fixedly connected to the second matching gear 82 on the same axis. The first transmission gear 71 is rotatably connected to the piston rod 10. The first transmission gear 71 is fixedly connected to the flywheel 5 on the same axis. The first transmission gear 71 meshes with the second transmission gear 72.

[0051] like Figure 3 As shown, the teeth of the first matching gear 81 and the second matching gear 82 are helical, which, through design, achieves a vertical transmission effect between the first matching gear 81 and the second matching gear 82. When vibration occurs, the piston rod 10 is displaced relative to the second outer sleeve 4. At this time, the first driving member or the second driving member is displaced relative to the first matching gear 81, thereby driving the first matching gear 81 to rotate. When the first matching gear 81 rotates, it drives the second matching gear 82 to rotate. The second matching gear 82 drives the second transmission gear 72 to rotate synchronously. The second transmission gear 72 drives the first transmission gear 71 to rotate, thereby driving the flywheel 5 to rotate synchronously through the first transmission gear 71.

[0052] Since the change of motion state of flywheel 5 requires external force, flywheel 5 can generate resistance to the rotation of the first matching gear 81 through the above-mentioned gear transmission process, so that the displacement of the first matching gear 81 relative to the first driving member or the second driving member is resisted, thereby generating a damping effect on the vibration of piston rod 10.

[0053] Further optimization of the scheme: the first driving component includes a long rack 63 fixedly connected to the inner wall of the second outer sleeve 4, the long rack 63 is arranged parallel to the piston rod 10, and a first matching gear 81 meshes with the long rack 63;

[0054] The second driving component includes a first short rack 61 and a second short rack 62 fixed on the inner wall of the second outer sleeve 4. The first short rack 61 and the second short rack 62 are parallel to the piston rod 10, and the first short rack 61 and the second short rack 62 are arranged along the same straight line. Another first matching gear 81 is correspondingly arranged with the first short rack 61 and the second short rack 62.

[0055] The design was further optimized by specially designing the tooth profiles of the first short rack 61, the second short rack 62, and the long rack 63 to ensure good meshing with the first matching gear 81.

[0056] like Figure 1 and Figure 3 As shown, during small displacement vibrations, only the long rack 63 meshes with a first matching gear 81 and drives the first matching gear 81 to rotate. At this time, the first matching gear 81 sequentially drives the corresponding flywheel 5 to rotate through the corresponding second matching gear 82, second transmission gear 72, and first transmission gear 71, producing a damping effect. The other first matching gear 81 moves back and forth between the first short rack 61 and the second short rack 62, without rotation.

[0057] When large displacement vibration occurs, the long rack 63 is still engaged with a first matching gear 81, while the other first matching gear 81 will engage with the first short rack 61 and the second short rack 62 in turn during the reciprocating motion due to the increased displacement of the piston rod 10, thereby driving the corresponding flywheel 5 to rotate. At this time, both sets of flywheels 5 rotate, achieving the effect of changing mass.

[0058] In a further optimized design, the elastic element includes several pre-compression springs 2. One end of each pre-compression spring 2 is fixedly connected to the inner wall of the first outer sleeve 3, and the other end of each pre-compression spring 2 is fixedly connected to the end of the piston rod 10 away from the piston 11.

[0059] like Figure 1 and Figure 5 As shown, the preload springs 2 are arranged in four groups of eight pairs, connected in a cross shape between the first outer sleeve 3 and the piston rod 10. The damper provides negative stiffness through the preload springs 2 in both large-displacement and small-displacement vibration stages.

[0060] In a further optimized design, a second earring 1 is fixedly connected to the end of the first outer sleeve 3 that is away from the second outer sleeve 4.

[0061] In a further optimized design, the end of the third outer sleeve 9 furthest from the second outer sleeve 4 is fixedly connected to the first earring 15.

[0062] like Figure 1 and Figure 2As shown, a first end cap is fixedly connected to the first earring 15. The first end cap has threads that match the third outer sleeve 9 and the inner sleeve 12. The first earring 15 is fixedly connected between the third outer sleeve 9 and the inner sleeve 12 through the first end cap. A second end cap is fixedly connected to the second earring 1. The second end cap has threads that match the first outer sleeve 3. The second earring 1 is fixedly connected to the end of the first outer sleeve 3 through the second end cap.

[0063] The working process of this embodiment is as follows:

[0064] When small displacement vibration occurs, the viscous liquid moves back and forth between the two rows of second damping holes 132 and on both sides of the first damping hole 131 under the push of the piston 11. At this time, the second damping holes 132 and the first damping holes 131 work together to generate damping. At the same time, there is a relative displacement between the long rack 63 and the meshing first matching gear 81, which drives the first matching gear 81 to rotate and finally drives the corresponding flywheel 5 to rotate, thus generating a damping effect.

[0065] When a large displacement vibration occurs, the piston 11 exceeds the position where the second damping hole 132 is set. At this time, only the first damping hole 131 plays a role, thereby achieving a variable damping effect. At the same time, due to the increase in displacement of the piston rod 10, the other first matching gear 81 meshes with the first short rack 61 and the second short rack 62 in the process of reciprocating with the piston rod 10, and finally drives the corresponding flywheel 5 to rotate. At this time, both sets of flywheels 5 rotate, thereby achieving a variable mass effect.

[0066] If the intervention compression spring 2 provides negative stiffness in both the large and small displacement vibration stages.

[0067] 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.

[0068] 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 negative stiffness vibration dual-controlled damper with variable mass and variable damping characteristics, characterized in that, include: Piston (11), with a piston rod (10) fixedly connected to one side of the piston (11); The main body of the viscous damper includes a piston chamber assembly, which is filled with a viscous liquid. The piston (11) is slidably disposed in the piston chamber assembly. A first flow element is provided on the piston chamber assembly. During small displacement vibration, the piston (11) is located between the inlet and outlet ends of the first flow element. The inertial mass body includes a second outer sleeve (4) fixedly connected to one end of the piston chamber assembly. The piston rod (10) slides through the second outer sleeve (4). Two sets of flywheel assemblies are provided on the piston rod (10). A first driving member and a second driving member are provided inside the second outer sleeve (4). During small displacement vibration, one of the flywheel assemblies is connected to the first driving member. During large displacement vibration, the two sets of flywheel assemblies are connected to the first driving member and the second driving member, respectively. The negative stiffness body includes a first outer sleeve (3), and the piston rod (10) is located inside the first outer sleeve (3) at one end away from the piston (11). The piston rod (10) and the first outer sleeve (3) are connected by an elastic element. The flywheel assembly includes a flywheel (5) rotatably connected to the piston rod (10) and a gear drive fixedly connected to the piston rod (10). The output end of the gear drive is driven by the flywheel (5), and the input end of the gear drive is driven by the first drive or the second drive. The gear drive includes a fixed plate (16) fixedly connected to the piston rod (10), a first matching gear (81) and a second matching gear (82) rotatably connected to the fixed plate (16), the first matching gear (81) and the second matching gear (82) meshing with each other, the first matching gear (81) being connected to the first drive or the second drive, the second matching gear (82) being fixedly connected to the second drive on the same axis, the piston rod (10) being rotatably connected to the first drive gear (71), the first drive gear (71) being fixedly connected to the flywheel (5) on the same axis, and the first drive gear (71) meshing with the second drive gear (72); The first driving component includes a long rack (63) fixedly connected to the inner wall of the second outer sleeve (4), the long rack (63) being arranged parallel to the piston rod (10), and a first matching gear (81) meshing with the long rack (63); The second driving component includes a first short rack (61) and a second short rack (62) fixedly mounted on the inner wall of the second outer sleeve (4). The first short rack (61) and the second short rack (62) are parallel to the piston rod (10) respectively, and the first short rack (61) and the second short rack (62) are arranged along the same straight line. Another first matching gear (81) is arranged correspondingly to the first short rack (61) and the second short rack (62).

2. The negative stiffness vibration dual-controlled damper with variable mass and variable damping characteristics according to claim 1, characterized in that: The piston chamber assembly includes a third outer sleeve (9) and an inner sleeve (12) disposed inside the third outer sleeve (9), and the first flow member is disposed between the inner sleeve (12) and the third outer sleeve (9).

3. A negative stiffness vibration dual-controlled damper with variable mass and variable damping characteristics according to claim 2, characterized in that: The first flow element includes a sealing material (14) filled between the inner sleeve (12) and the third outer sleeve (9). The sealing material (14) is used to create a cavity between the outer wall of the inner sleeve (12) and the inner wall of the third outer sleeve (9). A plurality of second damping holes (132) are provided on the side wall of the inner sleeve (12). The plurality of second damping holes (132) are arranged in two rows along the axial direction of the inner sleeve (12). The two rows of second damping holes (132) are connected through the cavity. During small displacement vibration, the piston (11) is located between the two rows of second damping holes (132). During large displacement vibration, the piston (11) is located outside the two rows of second damping holes (132).

4. A negative stiffness vibration dual-controlled damper with variable mass and variable damping characteristics according to claim 1, characterized in that: The piston (11) is also provided with a plurality of first damping holes (131), which are used to connect the viscous liquid on both sides of the piston (11).

5. A negative stiffness vibration dual-controlled damper with variable mass and variable damping characteristics according to claim 1, characterized in that: The elastic element includes a plurality of preloaded springs (2), one end of which is fixedly connected to the inner wall of the first outer sleeve (3), and the other end of which is fixedly connected to the end of the piston rod (10) away from the piston (11).

6. A negative stiffness vibration dual-controlled damper with variable mass and variable damping characteristics according to claim 1, characterized in that: A second earring (1) is fixedly connected to the end of the first outer sleeve (3) away from the second outer sleeve (4).

7. A negative stiffness vibration dual-controlled damper with variable mass and variable damping characteristics according to claim 2, characterized in that: The third outer sleeve (9) is fixedly connected to the first earring (15) at the end away from the second outer sleeve (4).

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