Gravity self-centering frictional sliding support

Abstract

The application provides a gravity self-resetting friction sliding support and belongs to the technical field of supports.The support comprises a first support plate, a rubber support body, a second support plate and at least one set of friction assemblies; the first support plate, the rubber support body and the second support plate are sequentially and fixedly overlapped along a first direction, and the friction assemblies are fixedly installed inside the rubber support body; the friction assemblies comprise a first friction plate and a second friction plate which are sequentially and fixedly overlapped along the first direction; the first friction plate has a first friction surface, the second friction plate has a second friction surface, the first friction surface and the second friction surface are both in a wave shape, the first friction surface and the second friction surface are oppositely arranged, and the first friction plate and the second friction plate are arranged in meshing relation with each other.The application sets the friction assemblies in the rubber support body, sets the first friction surface and the second friction surface in a wave shape, reduces the probability of tearing the rubber support body, simultaneously realizes the self-resetting capability of the support by relying on gravity, overcomes the shortcoming that the traditional self-resetting support needs an additional spring device, greatly improves the post-earthquake practical performance of the support, and realizes the post-earthquake self-resetting of the support by using low cost.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of bearings, and particularly relates to a gravity self-resetting friction sliding bearing. BACKGROUND

[0002] In the prior art, rubber bearings and friction pendulum bearings are the most widely used isolation bearings in actual engineering. However, the isolation bearings commonly used in existing engineering cannot well balance energy dissipation and post-earthquake recoverability.

[0003] In rubber bearings, lead rubber bearings or high-damping rubber bearings with good energy dissipation capacity are usually selected. However, both the investigation results of earthquake damage and experimental researches show that the energy dissipation caused by the strain hysteresis of lead plastic deformation or high-damping rubber will cause large residual displacement of the bearing, and even cause rubber tearing. This seriously affects the post-earthquake recoverability and isolation performance of the rubber bearing, and also increases the replacement or repair cost after the earthquake.

[0004] Friction pendulum bearings can theoretically balance good period extension capacity, energy dissipation capacity and certain reset capacity. However, some earthquake damage and test results show that, in order to achieve good isolation effect, the curvature radius of the friction pendulum bearing is usually large, and its mechanical geometric characteristics determine that the closer the slider is to the geometric center, the smaller the restoring force is, so as to be unable to overcome the friction force to realize self-resetting. SUMMARY

[0005] The application aims to provide a gravity self-resetting friction sliding bearing to solve the above technical problems in the prior art.

[0006] The application is achieved in the following manner:

[0007] The gravity self-resetting friction sliding bearing provided by the application comprises a first bearing plate, a rubber bearing body, a second bearing plate and at least one group of friction assemblies. The first bearing plate, the rubber bearing body and the second bearing plate are sequentially and fixedly overlapped along a first direction, and the friction assemblies are fixedly installed inside the rubber bearing body. The friction assembly comprises a first friction plate and a second friction plate which are sequentially and fixedly overlapped along the first direction. The first friction plate has a first friction surface, and the second friction plate has a second friction surface. Both the first friction surface and the second friction surface are in a wave shape, the first friction surface and the second friction surface are oppositely arranged, and the first friction plate and the second friction plate are arranged in meshing relationship.

[0008] The application has the following beneficial effects:

[0009] In the application, by setting the friction assembly in the rubber support body, in the earthquake, after the shear deformation of the rubber support body reaches the design target value, the first friction plate and the second friction plate in the friction assembly can rub each other to dissipate the earthquake force, so as to avoid the further deformation of the rubber support body for dissipating the earthquake force, avoid the large residual displacement of the support, and avoid the tearing of the rubber; and the first friction plate and the second friction plate are engaged by the wavy first friction surface and the second friction surface, the wavy structure can provide a resetting force for the first friction plate and the second friction plate, so that the support has a tendency to return to the initial state under the action of gravity, and the wavy structure increases the action point of the resetting force between the first friction plate and the second friction plate, and enhances the resetting ability of the support; at the same time, since the friction assembly is located in the interior of the rubber support body, the first friction plate and the second friction plate can also be provided with a resetting force during the deformation recovery process of the rubber support body, further improving the resetting ability of the support; the self-resetting ability of the support can be realized by relying on gravity, overcoming the shortcomings of the traditional self-resetting support that requires an additional spring device, greatly improving the post-earthquake practical performance of the support, and realizing the post-earthquake self-resetting of the support at low cost. BRIEF DESCRIPTION OF DRAWINGS

[0010] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the following will briefly introduce the drawings needed to be used in the embodiments of the present application or the prior art description. Obviously, the drawings described below are only some embodiments of the present application, and other drawings can also be obtained by those skilled in the art without creative labor on the basis of these drawings.

[0011] Figure 1 is the overall structure of the support provided by some embodiments of the present application Figure 1 ;

[0012] Figure 2 is the split structure of the support provided by some embodiments of the present application Figure 1 ;

[0013] Figure 3 is the structure diagram of the friction assembly provided by some embodiments of the present application;

[0014] Figure 4 is the overall structure of the support provided by some embodiments of the present application Figure 2 ;

[0015] Figure 5 is the split structure of the support provided by some embodiments of the present application Figure 2 ;

[0016] Figure 6 is the top view of the support provided by some embodiments of the present application;

[0017] Figure 7 is a structural diagram of a second friction plate provided by some embodiments of the present application Figure 1 ;

[0018] Figure 8 is a structural diagram of a second friction plate provided by some embodiments of the present application Figure 2 ;

[0019] Figure 9 is a structural diagram of a rubber support body and a friction assembly provided by some embodiments of the present application.

[0020] In the figure: 100 - first support plate, 200 - rubber support body, 210 - first mounting groove, 220 - second mounting groove, 230 - third mounting groove, 300 - second support plate, 400 - friction assembly, 410 - first friction plate, 411 - first friction surface, 420 - second friction plate, 421 - second friction surface, 500 - flat steel plate, 600 - first sealing plate, 700 - second sealing plate, 800 - connecting bolt. DETAILED DESCRIPTION

[0021] The following description provides many different embodiments, or examples, for implementing different features of the application. Specific examples are described in the following detail so as to provide a thorough understanding of the application. The description and drawings are not intended to limit the application to the described examples, but serve to provide examples to help explain the application.

[0022] Embodiments of the present application provide a gravity self-resetting friction sliding support, as shown in Figure 1 , Figure 2 , Figure 4 and Figure 5 , the support includes a first support plate 100, a rubber support body 200, a second support plate 300, and at least one set of friction assemblies 400.

[0023] The first support plate 100, the rubber support body 200, and the second support plate 300 are sequentially and fixedly arranged, and the overlapping direction of the three is defined as the first direction, which can be referred to the direction shown by the dashed line in Figures 1 to 5 . The rubber support body 200 is fixed between the first support plate 100 and the second support plate 300, and the rubber support body 200 serves as the main component of the support, and deforms to adapt to the change of the positions of the first support plate 100 and the second support plate 300 when the relative positions of the first support plate 100 and the second support plate 300 change.

[0024] In actual use, one of the first support plate 100 and the second support plate 300 is fixed with the bridge superstructure, and the other is fixed with the bridge substructure. The main manufacturing material of the rubber support body 200 is rubber, which has a certain elasticity and can deform under external force. The rubber support body 200 is fixed between the first support plate 100 and the second support plate 300, adapts to the position change between the first support plate 100 and the second support plate 300, and adapts to the vibration of the bridge, so that the bridge can operate normally. And the rubber support body 200 can restore the deformation after the external force disappears.

[0025] The support can be a bridge support for the bridge field, or a building support for the building field, or other fields that need to use the support.

[0026] Reference Figure 1 and Figure 4 As shown in FIG. 4, the friction assembly 400 is fixedly installed inside the rubber support body 200. The friction assembly 400 includes a first friction plate 410 and a second friction plate 420 which are arranged in the first direction. The overlapping direction of the first friction plate 410 and the second friction plate 420 is the same as the overlapping direction of the first support plate 100, the rubber support body 200 and the second support plate 300. Figure 3 As shown in FIG. 4, the first friction plate 410 has a first friction surface 411, and the second friction plate 420 has a second friction surface 421. Both the first friction surface 411 and the second friction surface 421 are in a wave shape. The wave shape is a shape with wave-like undulating characteristics. The first friction surface 411 undulates to form a plurality of grooves or protrusions, and the second friction surface 421 undulates to form a plurality of grooves or protrusions. The first friction surface 411 and the second friction surface 421 are arranged opposite to each other, and the grooves or protrusions of the first friction surface 411 and the protrusions or grooves of the second friction surface 421 are engaged with each other, so that the first friction plate 410 and the second friction plate 420 are engaged with each other. In this way, the post-earthquake self-resetting of the support can be realized under the action of gravity. The first friction surface 411 and the second friction surface 421 can be smooth curved surface structures, or can be formed by continuous bending of planes.

[0027] In the case where the length of the bridge changes due to temperature changes, material shrinkage, creep and the like, the first support plate 100 and the second support plate 300 can move relatively, thereby adapting to the position change between the bridge superstructure and the bridge substructure.

[0028] In the case of a low-intensity earthquake, the first support plate 100 and the second support plate 300 are displaced relative to each other, the rubber support body 200 is deformed to play a shock isolation function, and the seismic force is dissipated. Due to the low intensity of the earthquake and the small relative displacement of the first support plate 100 and the second support plate 300, the rubber support body 200 can be self-reset after deformation. As the intensity of the earthquake increases, the relative displacement of the first support plate 100 and the second support plate 300 further increases, and when the shear deformation of the rubber support body 200 reaches the design target value, the first friction plate 410 and the second friction plate 420 in the friction assembly 400 can be rubbed against each other to dissipate the seismic force, limit the continuous increase of the rubber shear strain, avoid further deformation of the rubber support body 200, and cause the rubber support body 200 to produce a large residual displacement and cause the rubber support body 200 to tear. In addition, under the action of a rare earthquake or even an extremely rare earthquake, the sliding displacement between the first friction plate 410 and the second friction plate 420 can approach the maximum design value, further limiting the increase of the rubber shear strain and reducing the possibility of tearing of the rubber support body 200.

[0029] Due to the presence of the friction assembly 400, the mutual movement of the first friction plate 410 and the second friction plate 420 can dissipate part of the seismic force, avoid further deformation of the rubber support body 200 to dissipate the seismic force, and reduce or even avoid the tearing of the rubber support body 200. Moreover, since the rubber support body 200 is elastic and the friction assembly 400 is installed inside the rubber support body 200, after the earthquake ends, the rubber support body 200 can also provide a resetting force for the first friction plate 410 and the second friction plate 420 during the recovery of the deformation, thereby facilitating the resetting of the first friction plate 410 and the second friction plate 420.

[0030] Since the first friction plate 410 and the second friction plate 420 are arranged in meshing through the first friction surface 411 and the second friction surface 421 in a wave shape, the surface of the wave shape structure can provide a plurality of meshing positions between the first friction plate 410 and the second friction plate 420. When the two friction plates are relatively displaced, there can be a plurality of contact points between the first friction plate 410 and the second friction plate 420. Since the contact positions of the two friction plates are inclined surfaces, under the action of gravity, the inclined surfaces can provide a reset force for the first friction plate 410 and the second friction plate 420, so that the support can have a tendency to return to the initial state under the action of gravity. Since there are a plurality of contact points between the first friction plate 410 and the second friction plate 420, the reset force received by the two can be more evenly distributed in itself, thereby enhancing the reset ability of the support. In addition, the friction assembly 400 is located inside the rubber support body 200, and the rubber support body 200 can also provide a reset force for the first friction plate 410 and the second friction plate 420 during the recovery of deformation, further improving the reset ability of the support. Moreover, in the reset process of the first friction plate 410 and the second friction plate 420, the two friction plates can also drive the rubber connected thereto to return to the initial state. The friction assembly 400 and the rubber support body 200 cooperate with each other to improve the recoverable ability of the support, and the self-resetting ability of the support can be realized by relying on gravity, overcoming the shortcomings of the traditional self-resetting support that requires an additional spring device, greatly improving the post-earthquake practical performance of the support, and realizing the post-earthquake self-resetting of the support at a low cost.

[0031] In some preferred embodiments, as shown in Figs. 1-3, the rubber support body 200 is provided with a plurality of first support plates 100. The first support plates 100 are arranged in parallel with the first direction, and the rubber is filled between adjacent two first support plates 100. The first support plates 100 improve the vertical bearing capacity of the rubber support body 200, and the first support plates 100 enhance the structural strength of the rubber support body 200, which can reduce the possibility of tearing of the rubber during deformation. Figure 1 、 Figure 2 、 Figure 4 and Figure 5 In some preferred embodiments, as shown in Figs. 1-3, the rubber support body 200 is provided with a plurality of first support plates 100. The first support plates 100 are arranged in parallel with the first direction, and the rubber is filled between adjacent two first support plates 100. The first support plates 100 improve the vertical bearing capacity of the rubber support body 200, and the first support plates 100 enhance the structural strength of the rubber support body 200, which can reduce the possibility of tearing of the rubber during deformation.

[0032] The friction assembly 400 installed in the rubber support body 200 can be fixedly installed between adjacent two planar steel plates 500. The first friction plate 410 and the second friction plate 420 are directly fixed with the planar steel plate 500, which improves the installation stability of the friction assembly 400 in the rubber support body 200. Moreover, in the reset process of the first friction plate 410 and the second friction plate 420 after the earthquake, the interaction force between the planar steel plate 500 and the friction assembly 400 is stronger, and the friction assembly 400 and the rubber support body 200 can reset faster.

[0033] In some embodiments of the present application, referring to Figures 1 to 5 As shown in the drawings, the circumferential side wall of the first friction plate 410 and the circumferential side wall of the second friction plate 420 in the friction assembly 400 are flush. The friction assembly 400 is fixed inside the rubber support body 200, and the circumferential side walls of the first friction plate 410 and the second friction plate 420 abut against the rubber support body 200. Since the circumferential side walls of the first friction plate 410 and the second friction plate 420 are flush, the surface of the rubber support body 200 abutting against the circumferential side walls of the first friction plate 410 and the second friction plate 420 is a flat surface, and the stress concentration points of this part of the rubber support body 200 are less. During the relative sliding of the first friction plate 410 and the second friction plate 420, the rubber support body 200 is less likely to be torn by pulling.

[0034] Further preferably, the circumferential side wall of the first friction plate 410 and the circumferential side wall of the second friction plate 420 are both arranged parallel to the first direction, so that the thickness of the rubber support body 200 wrapped around the circumferential direction of the friction assembly 400 can remain stable along the first direction, thereby ensuring the structural stability of the rubber support body 200. The thickness of the rubber support body 200 refers to the thickness of the rubber support body 200 between the circumferential side wall of the rubber support body 200 and the circumferential side wall of the friction assembly 400 in the radial direction of the support.

[0035] The friction assembly 400 is fixedly installed between two adjacent plane steel plates 500. In some embodiments of the present application, referring to Figure 1 and Figure 2 As shown in the drawings, the projection of the friction assembly 400 on the plane steel plate 500 along the first direction is located within the range of the plane steel plate 500, that is, in the radial direction of the support, the size of the friction assembly 400 is smaller than the size of the plane steel plate 500. The smaller the size of the friction assembly 400, the thicker the thickness of the rubber support body 200 wrapped around it. In the case of sliding of the first friction plate 410 and the second friction plate 420, the rubber support body 200 has a higher ability to withstand lateral load and is less likely to be torn.

[0036] The number of friction assemblies 400 in the rubber support body 200 is generally selected according to the target equivalent damping ratio. If the designed damping ratio is high, more friction assemblies 400 can be arranged, and vice versa. In the friction assembly 400, the friction coefficient between the first friction plate 410 and the second friction plate 420 is determined according to the design needs. In some embodiments, the friction coefficient can be set to between 0.03 and 0.15, which enhances the energy dissipation capacity of the support without affecting the resetting capacity of the rubber support body 200.

[0037] In the case that the number of friction assemblies 400 is greater than or equal to two, the multiple sets of friction assemblies 400 are arranged in parallel inside the rubber support body 200, and a certain distance is required between the adjacent two sets of friction assemblies 400 to reduce the influence on the structural strength of the rubber support body 200. In some embodiments of the present application, the number of planar steel plates 500 between the adjacent two sets of friction assemblies 400 is greater than or equal to three, and the adjacent planar steel plates 500 are filled with rubber, so that at least two layers of rubber are spaced between the adjacent two sets of friction assemblies 400. The friction assemblies 400 are spaced and distributed, and both sets of friction assemblies 400 can be fully utilized when dissipating seismic forces.

[0038] In addition, in some embodiments of the present application, the thickness of the planar steel plate 500 is less than the distance between the adjacent two planar steel plates 500. The planar steel plate 500 should not be too thick, otherwise it will affect the buffering and seismic isolation effect of the rubber support body 200.

[0039] In other embodiments of the present application, as shown in Figure 2 the surface of the rubber support body 200 close to the first support plate 100 is concave to form a first mounting groove 210, and the first mounting groove 210 is fixedly installed with a first sealing plate 600, the first sealing plate 600 is fixedly connected with the first support plate 100, and the circumferential side wall of the first sealing plate 600 is tightly matched with the inner wall of the first mounting groove 210.

[0040] The first sealing plate 600 is embedded in the rubber support body 200, the rubber support body 200 is connected with the first support plate 100 through the first sealing plate 600, and part of the rubber support body 200 is arranged around the first sealing plate 600, which can improve the stability of the overall structure of the support. If the rubber support body 200 is directly connected with the first support plate 100, the connection structure between the rubber support body 200 and the first support plate 100 is easily damaged after shear deformation, which affects the normal use of the support.

[0041] And / or, as shown in Figure 2 the surface of the rubber support body 200 close to the second support plate 300 is concave to form a second mounting groove 220, and the second mounting groove 220 is fixedly installed with a second sealing plate 700, the second sealing plate 700 is fixedly connected with the second support plate 300, and the circumferential side wall of the second sealing plate 700 is tightly matched with the inner wall of the second mounting groove 220. The second sealing plate 700 is embedded in the rubber support body 200, and the connection stability of the rubber support body 200 and the second support plate 300 is improved by arranging the second sealing plate 700.

[0042] In specific implementation, the second sealing plate 700 and the second support plate 300, and the first sealing plate 600 and the first support plate 100 are usually fixed by connecting bolts 800.

[0043] In some embodiments of the present application, the friction assembly 400 is directly connected with the first support plate 100 or the second support plate 300. For details, please refer to Figure 4 and Figure 5 As shown, the surface of the rubber support body 200 close to the first support plate 100 and / or the second support plate 300 is concave to form a third mounting groove 230, the friction assembly 400 is fixedly installed in the third mounting groove 230, and the friction assembly 400 is fixedly connected with the first support plate 100 or the second support plate 300 corresponding to the third mounting groove 230, and the circumferential side wall of the friction assembly 400 is tightly matched with the inner wall of the third mounting groove 230.

[0044] The rubber support body 200 is directly connected with the first support plate 100 and the second support plate 300 through the friction assembly 400, which improves the connection stability of the rubber support body 200 and the first support plate 100 and the second support plate 300. The first support plate 100 or the second support plate 300 corresponding to the third mounting groove 230 means that if the third mounting groove 230 is arranged on the surface of the rubber support body 200 close to the first support plate 100, the third mounting groove 230 corresponds to the first support plate 100; if the third mounting groove 230 is arranged on the surface of the rubber support body 200 close to the second support plate 300, the third mounting groove 230 corresponds to the second support plate 300.

[0045] A group of friction assemblies 400 are installed in one third mounting groove 230, and the top and the bottom of the rubber support body 200 can be provided with the friction assembly 400, or only the top or the bottom can be provided with the friction assembly 400. The side close to the first support plate 100 of the rubber support body 200 is the top, and the side close to the second support plate 300 is the bottom. The inner wall of the third mounting groove 230 is tightly matched with the circumferential side wall of the friction assembly 400 to stabilize the position of the friction assembly 400.

[0046] In some embodiments of the present application, the number of friction assemblies 400 is set to one group or more than one group. In each group of friction assemblies 400, the first friction plate 410 and the second friction plate 420 are limited and matched in the same direction, the support corresponding to the friction assembly 400 is a one-way support, and the seismic force is dissipated in the limiting direction of the first friction plate 410 and the second friction plate 420.

[0047] In some embodiments of the present application, the friction assembly 400 is provided with two groups or more than two groups. For details, please refer to Figure 9As shown, in one set of friction components 400, the first friction plate 410 and the second friction plate 420 are mutually restrictive and engaged along a second direction, and in another set of friction components 400, the first friction plate 410 and the second friction plate 420 are mutually restrictive and engaged along a third direction. Both the second and third directions are perpendicular to the first direction and intersect with it. The first direction is referenced... Figure 9 The y-axis direction is shown, and the second direction is referenced. Figure 9 The x-axis direction shown is a third-party reference. Figure 9 The z-axis direction is shown. This support is a two-way decoupled support, capable of dissipating seismic forces in both the second and third directions.

[0048] In both unidirectional and bidirectional decoupled supports, the structures of the first friction plate 410 and the second friction plate 420 can be referenced. Figure 8 As shown,

[0049] In other embodiments of this application, reference is made to Figure 6 and Figure 7 As shown, the first friction plate 410 and the second friction plate 420 are radially positioned and engaged with the support. The groove or protrusion formed by the first friction surface 411 and the second friction surface 421 is annular, allowing the first friction plate 410 and the second friction plate 420 to be radially positioned and engaged with the support. When the support moves in any radial direction, the first friction plate 410 and the second friction plate 420 can slide and engage, dissipating seismic forces. This support is a universal support.

[0050] The cross-section of the rubber support body 200 can be circular or square, and no limitation is made in the embodiments provided in this application.

[0051] 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, and improvements made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A gravity self-centering frictional sliding support, characterized in that, The rubber support body (200) is internally provided with a plurality of planar steel plates (500), the planar steel plates (500) are arranged in parallel with the first support plate (100), and a plurality of the planar steel plates (500) are arranged along the first direction. The first support plate (100), the rubber support body (200) and the second support plate (300) are sequentially and fixedly overlapped along a first direction, and the friction assembly (400) is fixedly installed inside the rubber support body (200). The friction assembly (400) comprises a first friction plate (410) and a second friction plate (420) which are sequentially and overlapped along the first direction, the first friction plate (410) has a first friction surface (411), the second friction plate (420) has a second friction surface (421), the first friction surface (411) and the second friction surface (421) are both in a wave shape, the first friction surface (411) and the second friction surface (421) are oppositely arranged, and the first friction plate (410) and the second friction plate (420) are arranged in meshing with each other. The first friction plate (410) and the second friction plate (420) are limitingly matched along the radial direction of the support.

2. A gravity self-centering frictional sliding support according to claim 1, characterized in that The rubber support body (200) is internally provided with a plurality of planar steel plates (500), the planar steel plates (500) are arranged in parallel with the first support plate (100), and a plurality of the planar steel plates (500) are arranged along the first direction.

3. A gravity self-centering frictional sliding support according to claim 2, characterized in that The circumferential side walls of the first friction plate (410) and the second friction plate (420) are arranged in flush, and are both arranged in parallel with the first direction.

4. A gravity self-centering frictional sliding support according to claim 2, characterized in that The projections of the friction assembly (400) on the adjacent planar steel plates (500) along the first direction are all located within the range of the planar steel plates (500).

5. A gravity self-centering frictional sliding support according to claim 2, characterized in that, The number of the planar steel plates (500) between the adjacent two groups of the friction assembly (400) is greater than or equal to three.

6. A gravity self-centering frictional sliding support according to claim 2, characterized in that The thickness of the planar steel plate (500) is less than the distance between the adjacent two planar steel plates (500).

7. A gravity self-centering frictional sliding support according to claim 1, characterized in that The surface of the rubber support body (200) close to the first support plate (100) is internally recessed to form a first installation groove (210), the first installation groove (210) is internally fixedly installed with a first sealing plate (600), the first sealing plate (600) is fixedly connected with the first support plate (100), and the circumferential side walls of the first sealing plate (600) are all abuttingly matched with the inner walls of the first installation groove (210). And / or, the surface of the rubber support body (200) close to the second support plate (300) is internally recessed to form a second installation groove (220), the second installation groove (220) is internally fixedly installed with a second sealing plate (700), the second sealing plate (700) is fixedly connected with the second support plate (300), and the circumferential side walls of the second sealing plate (700) are all abuttingly matched with the inner walls of the second installation groove (220).

8. A gravity self-centering frictional sliding support according to claim 1, characterized in that The surface of the rubber support body (200) close to the first support plate (100) and / or the second support plate (300) is concave to form a third mounting groove (230), the friction assembly (400) is fixedly installed in the third mounting groove (230), and the friction assembly (400) is fixedly connected with the first support plate (100) or the second support plate (300) corresponding to the third mounting groove (230), and the circumferential side wall of the friction assembly (400) is abuttingly matched with the inner wall of the third mounting groove (230).

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