Design method for friction layer of metal joint in hinge device of low-floor vehicle

Abstract

The invention discloses a method for designing a friction layer of a metal joint in a low-floor vehicle hinging device, the metal joint comprises a metal joint outer seat sleeve, an outer rolling ball sleeve arranged in the metal joint outer seat sleeve and an inner limiting block arranged in the outer rolling ball sleeve, and the outer rolling ball sleeve and the inner limiting block are in spherical surface contact. According to the flexible friction layer design method, a first flexible friction layer is arranged between the metal joint outer seat sleeve and the outer rolling ball sleeve, and a second flexible friction layer is arranged between the outer rolling ball sleeve and the spherical surface of the inner limiting block. And when the inner limiting block is locked on the metal joint outer seat sleeve through a bolt to enable the inner limiting block, the outer rolling ball sleeve and the metal joint outer seat sleeve to form a metal joint, the outer rolling ball sleeve is in spherical surface contact with the first flexible friction layer. The friction layer in the metal joint can realize flexible friction contact in various working conditions, so that the problem of excessive wear is avoided, and the service life of the whole product is prolonged.

Description

Technical Field

[0001] The invention relates to a friction layer design method, in particular to a friction layer design method for a metal joint in an articulated device of a low-floor vehicle, and belongs to the technical field of low-floor vehicle articulated device manufacturing. Background Art

[0002] Low-floor light rail vehicles (hereinafter referred to as low-floor vehicles) are a new type of modern urban transportation equipment. They are generally composed of three, five, or seven vehicles connected by an articulated system, with the vehicles below 40 cm from the track surface. The articulation system is a key component of the vehicle body connection of urban low-floor vehicles. With the widespread use of low-floor vehicles in Europe and the promotion of low-floor vehicles in China, the market demand for articulation systems is also growing.

[0003] The body articulation device is arranged at the connecting parts at both ends of the body, generally adopting the upper and lower hinge supports. Its main function is to connect multiple low-floor carriages, while meeting the vehicle's traction and braking force transmission requirements, and adapting to the needs of the vehicle passing through small-radius horizontal and vertical curves in urban traffic.

[0004] The Chinese invention patent application with application publication number CN105822665A and application publication date August 3, 2016 discloses an integral metal spherical joint bearing in a fixed hinge of a low-floor vehicle, including a metal joint outer seat sleeve, an outer rolling ball sleeve arranged inside the metal joint outer seat sleeve, an inner rolling ball arranged inside the outer rolling ball sleeve, and a wear-resistant bushing arranged between the metal joint outer seat sleeve and the outer rolling ball sleeve: the inner rolling ball and the outer rolling ball sleeve, as well as the outer rolling ball sleeve and the wear-resistant bushing are all in spherical contact, and the metal joint outer seat sleeve, the outer rolling ball sleeve, the inner rolling ball and the wear-resistant bushing are assembled into an integral metal spherical joint bearing by screws.

[0005] As can be seen from the aforementioned patent documents, when the product is rotating or swinging, its wear-resistant bushings come into hard contact with other components. For example, wear-resistant bushing 1 and the outer rolling ball housing create hard frictional contact, which can cause excessive wear. When the product is in traction or braking conditions, wear-resistant bushing 2 and the inner rolling ball also create hard frictional contact, similarly causing excessive wear and reducing service life.

[0006] In summary, how to provide a friction layer design method for the metal joints in the articulated device of a low-floor vehicle so that the friction layer inside the metal joints can achieve flexible friction contact under various working conditions, thereby avoiding the occurrence of excessive wear and improving the service life of the entire product is a technical problem that needs to be solved urgently. Summary of the Invention

[0007] The technical problem to be solved by the present invention is to address the defects existing in the existing technology and provide a friction layer design method for the metal joints in the articulated device of a low-floor vehicle. The friction layer inside the metal joint designed by this method can achieve flexible friction contact under various working conditions, thereby avoiding the occurrence of excessive wear problems and improving the service life of the entire product.

[0008] In order to solve the above technical problems, the technical solution adopted by the present invention is: a friction layer design method for a metal joint in a low-floor vehicle articulation device, the metal joint includes a metal joint outer seat sleeve, an outer rolling ball sleeve arranged inside the metal joint outer seat sleeve and an inner limit block arranged inside the outer rolling ball sleeve, and the outer rolling ball sleeve and the inner limit block are in spherical contact. The flexible friction layer design method is to set a flexible friction layer one between the metal joint outer seat sleeve and the outer rolling ball sleeve, and set a flexible friction layer two between the outer rolling ball sleeve and the spherical surface of the inner limit block; when the inner limit block is locked on the metal joint outer seat sleeve by bolts so that the inner limit block, the outer rolling ball sleeve and the metal joint outer seat sleeve form a metal joint, the outer rolling ball sleeve and the flexible friction layer one are in spherical contact.

[0009] Preferably, the flexible friction layer includes rubber and a wear-resistant ball sleeve. The wear-resistant ball sleeve is bonded to the inside of the outer seat sleeve of the metal joint by vulcanization of the rubber. The wear-resistant ball sleeve is in spherical contact with the outside of the outer rolling ball sleeve.

[0010] Preferably, the flexible friction layer 2 includes rubber 2 and wear-resistant ball sleeve 2, the wear-resistant ball sleeve 2 is arranged on the inner spherical surface of the outer rolling ball sleeve, the rubber is vulcanized and bonded to the outer spherical surface of the inner limit block, and a gap H is left between the rubber 2 and the wear-resistant ball sleeve 2.

[0011] Preferably, an inlay groove 1 is opened on the inner spherical surface of the outer rolling ball sleeve, and the wear-resistant ball sleeve 2 is embedded in the inlay groove 1, so that the wear-resistant ball sleeve 2 is arranged on the inner spherical surface of the outer rolling ball sleeve.

[0012] Preferably, an oil storage groove is provided on the contact spherical surface between the wear-resistant ball sleeve 1 and the outer rolling ball sleeve.

[0013] Preferably, an upwardly extending shaft column is also provided on the inner spherical surface of the metal joint outer seat sleeve, and the shaft column and the metal joint outer seat sleeve are an integrated structure. The rubber one includes a spherical rubber body, and the spherical rubber body is vulcanized and bonded between the inner spherical surface of the metal joint outer seat sleeve and the outer spherical surface of the wear-resistant ball sleeve one. One end of the spherical rubber body extends to form a sleeve-shaped rubber body, and the sleeve-shaped rubber body is used to wrap the outer peripheral surface of the shaft column.

[0014] Preferably, a stepped protrusion is provided at the top of the shaft column, and a stepped groove matching the stepped protrusion is provided on the bottom surface of the inner limit block; during installation, the stepped protrusion and the stepped groove are matched and contacted, so that the inner limit block is snapped into the shaft column of the metal joint outer seat sleeve, and then the inner limit block is locked to the metal joint outer seat sleeve by bolts so that the inner limit block, wear-resistant ball sleeve 2, outer rolling ball sleeve, wear-resistant ball sleeve 1 and metal joint outer seat sleeve form a metal joint.

[0015] Preferably, a spacer is provided inside the spherical rubber body, and an inlay groove is provided on the side of the spacer; the spacer is first bonded to the outer seat sleeve of the metal joint through rubber vulcanization, and then the wear-resistant ball sleeve is embedded in the inlay groove on the spacer, so that a wear-resistant ball sleeve is vulcanized inside the outer seat sleeve of the metal joint through rubber vulcanization.

[0016] Preferably, an annular step portion is provided near the inner top of the outer rolling ball sleeve, an annular groove is provided on the annular step portion, and a sealing ring is provided in the annular groove; during assembly, a sealing structure is formed by pressing the top plate against the annular step portion, thereby utilizing the top plate to press and contact the sealing ring.

[0017] The beneficial effects of the present invention are as follows: by designing flexible friction layer 1 and flexible friction layer 2, when the metal joint is in rotation or swinging conditions, the outer seat sleeve of the metal joint and the outer rolling ball sleeve are in flexible friction contact through the provision of flexible friction layer 1. When the metal joint is in traction or braking conditions, the outer rolling ball sleeve and the spherical surface of the inner limit block are in flexible friction contact through flexible friction layer 2. This ensures that the metal joint of the present invention can achieve flexible friction contact in various operating conditions, thereby avoiding the occurrence of excessive wear and extending the service life of the entire product. In addition, the provision of rubber can also reduce noise and vibration generated by the vehicle body. In addition, by designing the specific structure of the flexible friction layer 1, when the metal joint rotates or swings at a small angle, it is the deformation of the rubber 1 located between the wear-resistant ball sleeve 1 and the outer seat sleeve of the metal joint that bears the pressure. At this time, the wear-resistant ball sleeve 1 and the outer rolling ball sleeve are relatively stationary. Only when the metal joint rotates or swings at a large angle, the acting force exceeds the static friction between the wear-resistant ball sleeve 1 and the outer rolling ball sleeve, the wear-resistant ball sleeve 1 and the outer rolling ball sleeve will move relative to each other to form a friction pair. At this time, the movement of the product is jointly borne by the deformation of the rubber 1 and the friction pair, which greatly improves the service life of the product. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 Schematic diagram of the axial cross-sectional structure of the metal joint in an embodiment of the present invention; Figure 2 for Figure 1A schematic diagram of the enlarged structure of the middle part A; Figure 3 for Figure 1 A schematic diagram of the enlarged structure of the middle part B; Figure 4 Schematic diagram of the axial cross-section structure of the low-floor vehicle articulation device according to an embodiment of the present invention Figure 5 for Figure 1 Schematic diagram of the enlarged structure of the middle C part; Figure 6 for Figure 1 The enlarged structural diagram of the middle D part; In the figure: 1. Metal joint outer seat sleeve; 111. Shaft column; 112. Step-shaped protrusion; 2. Outer rolling ball sleeve; 211. Annular step; 212. Annular groove; 3. Inner limit block; 311. Step-shaped groove; 4. Flexible friction layer 1; 41. Rubber 1; 411. Spherical rubber body; 412. Sleeve-shaped rubber body; 42. Wear-resistant ball sleeve 1; 5. Flexible friction layer 2; 51. Rubber 2; 52. Wear-resistant ball sleeve 2; 6. Bolt; 7. Inlay groove 1; 8. Metal joint; 9. Upper fixed support; 10. Lower fixed support; 11. Sealing ring; 12. Top plate; 13. Spacer; 14. Inlay groove 2; 15. Oil storage tank. DETAILED DESCRIPTION

[0019] The technical solution of the present invention is further described in detail below with reference to the accompanying drawings and specific embodiments.

[0020] Example: Figure 1As shown, a friction layer design method for a metal joint in an articulated device of a low-floor vehicle is shown, wherein the metal joint includes a metal joint outer seat sleeve 1, an outer rolling ball sleeve 2 arranged inside the metal joint outer seat sleeve 1, and an inner limit block 3 arranged inside the outer rolling ball sleeve 2, and the relative surfaces between the outer rolling ball sleeve 2 and the inner limit block 3 are both set to spherical surfaces that match each other. The flexible friction layer design method is to set a flexible friction layer 1 4 between the metal joint outer seat sleeve 1 and the outer rolling ball sleeve 2, and set a flexible friction layer 2 5 between the outer rolling ball sleeve 2 and the spherical surface of the inner limit block 3; when the inner limit block 3 is locked on the metal joint outer seat sleeve 1 by a bolt 6 so that the inner limit block 3, the outer rolling ball sleeve 2 and the metal joint outer seat sleeve 1 form a metal joint, the outer rolling ball sleeve 2 is in spherical contact with the flexible friction layer 1 4. In this embodiment, when the metal joint is rotating or swinging, the outer seat sleeve and the outer rolling ball sleeve maintain flexible frictional contact via the flexible friction layer 1. When the metal joint is traction or braking, the outer rolling ball sleeve maintains flexible frictional contact with the spherical surface of the inner stopper via the flexible friction layer 2. This ensures that the metal joint in this embodiment maintains flexible frictional contact in all operating conditions, thereby preventing excessive wear and extending the service life of the entire product. Furthermore, the provision of rubber can reduce noise and vibration generated by the vehicle body.

[0021] like Figure 1 and Figure 2 As shown, the flexible friction layer 4 comprises rubber 41 and a wear-resistant ball sleeve 42. The wear-resistant ball sleeve 42 is vulcanized and bonded to the interior of the metal joint outer seat 1. The wear-resistant ball sleeve 42 forms spherical contact with the exterior of the outer rolling ball sleeve 2. When the metal joint is rotating or swinging, flexible friction contact is formed between the flexible friction layer 4 and the outer rolling ball sleeve 2. In the patent literature mentioned in the background technology, when the product rotates or swings, whether it is a large-angle movement or a small-angle movement, it is borne by the friction pair formed between the wear-resistant bushing and the outer rolling ball sleeve. This will easily cause excessive wear after working for a long time, thereby reducing the service life of the product. In the present embodiment, when the metal joint rotates or swings at a small angle, it is the deformation of the rubber located between the wear-resistant ball sleeve and the outer seat sleeve of the metal joint that bears the force. At this time, the wear-resistant ball sleeve and the outer rolling ball sleeve are relatively stationary. Only when the metal joint rotates or swings at a large angle, the force exceeds the static friction between the wear-resistant ball sleeve and the outer rolling ball sleeve, the wear-resistant ball sleeve and the outer rolling ball sleeve will move relative to each other to form a friction pair. At this time, the movement of the product is jointly borne by the deformation of the rubber and the friction pair, which greatly improves the service life of the product.

[0022] like Figure 1 and Figure 3As shown, the flexible friction layer 5 includes a second rubber member 51 and a second wear-resistant ball sleeve 52. The second wear-resistant ball sleeve 52 is disposed on the inner spherical surface of the outer rolling ball sleeve 2. The second rubber member 51 is vulcanized and bonded to the outer spherical surface of the inner stop block 3. When the metal joint is in a rotating or swinging state, a gap H is left between the second rubber member 51 and the second wear-resistant ball sleeve 52. When the metal joint is in a traction or braking state, the gap H becomes zero, and the second rubber member 51 and the second wear-resistant ball sleeve 52 are in flexible frictional contact. Thus, flexible frictional contact between the outer rolling ball sleeve 2 and the inner stop block 3 is achieved through the flexible friction layer 5.

[0023] In this embodiment, an inlay groove 1 7 is formed on the inner spherical surface of the outer rolling ball sleeve 2, and the wear-resistant ball sleeve 2 52 is embedded in the inlay groove 1 7, thereby placing the wear-resistant ball sleeve 2 52 on the inner spherical surface of the outer rolling ball sleeve 2. This embedded structure design facilitates subsequent replacement of the wear-resistant ball sleeve 2 and reduces maintenance costs.

[0024] like Figure 4 As shown, the entire metal joint 8 connects adjacent vehicle bodies via an upper fixed support 9 and a lower fixed support 10. The entire metal joint 8 is used in vehicle body articulation systems to meet complex loading conditions, including vertical, lateral, longitudinal, and large torsional angles. The metal joint 8 is self-centering, with the spherical surfaces of the metal joint's outer seat sleeve 1, the wear-resistant ball sleeve 1 42, the outer rolling ball sleeve 2, the wear-resistant ball sleeve 2 52, and the inner limit block 3 all sharing a common center. The metal joint 8 can perform three independent relative rotations about this center. Both the wear-resistant ball sleeve 1 42 and the wear-resistant ball sleeve 2 52 can be made of wear-resistant materials such as polyester, copper-inlaid graphite, or PTFE.

[0025] like Figure 1As shown, an upwardly extending shaft column 111 is also provided on the inner spherical surface of the metal joint outer seat sleeve 1, and the shaft column 111 and the metal joint outer seat sleeve 1 are an integrated structure. The rubber 141 includes a spherical rubber body 411, and the spherical rubber body 411 is vulcanized and bonded between the inner spherical surface of the metal joint outer seat sleeve 1 and the outer spherical surface of the wear-resistant ball sleeve 142. One end of the spherical rubber body 411 extends to form a sleeve-shaped rubber body 412, and the sleeve-shaped rubber body 412 is used to wrap the outer peripheral surface of the shaft column 111. This design has one function of wrapping the shaft column with the sleeve-shaped rubber body to achieve rust and corrosion prevention functions. Another function is to increase the overall volume of the rubber and the vulcanization bonding area between the rubber and the metal joint outer seat sleeve, thereby further improving the overall strength of the rubber. A stepped protrusion 112 is provided at the top of the shaft column 111, and a stepped groove 311 matching the stepped protrusion 112 is provided on the bottom surface of the inner limit block 3. During installation, the stepped protrusion 112 is matched with the stepped groove 311 to make the inner limit block 3 snap into the shaft column 111 of the metal joint outer seat sleeve 1, and then the inner limit block 3 is locked on the metal joint outer seat sleeve 1 by using the bolt 6 so that the inner limit block 3, the wear-resistant ball sleeve 2 52, the outer rolling ball sleeve 2, the wear-resistant ball sleeve 1 42 and the metal joint outer seat sleeve 1 form a metal joint.

[0026] like Figure 1 and Figure 5 As shown, an annular step 211 is provided near the inner top of the outer rolling ball sleeve 2. An annular groove 212 is provided on the annular step 211, and a sealing ring 11 is disposed in the annular groove 212. During assembly, the top plate 12 is pressed against the annular step 211, thereby forming a seal structure with the top plate 12 in contact with the sealing ring 11, further improving the sealing performance of the entire product. The top plate 12 can be made of materials such as nylon.

[0027] like Figure 1 and Figure 6 As shown, a spacer 13 is disposed within the spherical rubber body 411. The spacer 13 may be multi-layered and made of metal. The presence of the spacer 13 within the spherical rubber body 411, particularly when multiple layers are provided, allows the product to have lower deflection and torsional stiffness, thereby minimizing the impact on the vehicle body's derived stiffness. This also ensures the product has higher vertical and radial stiffness, further optimizing the product's mechanical properties and extending its service life.

[0028] like Figure 6As shown, a second inlay groove 14 is provided on the side of a spacer sleeve 13 closest to the outer rolling ball sleeve 2. During manufacturing, the spacer sleeve 13 is first bonded to the metal joint outer seat sleeve 1 by vulcanization of rubber 1 41, and then the wear-resistant ball sleeve 1 42 is embedded in the second inlay groove 14 on the spacer sleeve 13, so that the wear-resistant ball sleeve 1 42 is bonded to the inside of the metal joint outer seat sleeve 1 by vulcanization of rubber 1 41. Here, if the wear-resistant ball sleeve 1 is directly bonded to the rubber 1 by vulcanization, the bonding effect between the two will not be very good due to the material properties of the two. In addition, since the wear-resistant ball sleeve 1 can be made of wear-resistant materials such as polyester, copper-inlaid graphite, or PTFE, in order to ensure its bonding effect, it is necessary to study and analyze the bonding properties of various materials, which is relatively complicated. In addition, if the wear-resistant ball sleeve 1 is bonded to the rubber 1 by vulcanization, it is inconvenient to replace the wear-resistant ball sleeve 1 later, which increases maintenance costs. Therefore, in this embodiment, the spacer sleeve is first vulcanized and bonded to the rubber sleeve, and then the wear-resistant ball sleeve is installed on the spacer sleeve using an embedded method. In this way, there is no need to consider the influence of the material properties of the wear-resistant ball sleeve on the bonding effect, thereby ensuring the installation effect of the wear-resistant ball sleeve, reducing the manufacturing difficulty, and in subsequent maintenance, the wear-resistant ball sleeve can be replaced conveniently and quickly, which also reduces maintenance costs.

[0029] like Figure 1 and Figure 2 As shown, an oil reservoir 15 is provided on the contact spherical surface between the wear-resistant ball sleeve 1 42 and the outer rolling ball sleeve 2. The oil reservoir 15 can be provided on the outer rolling ball sleeve 2 or, as in this embodiment, on the wear-resistant ball sleeve 1 42. During operation, the lubricating grease stored in the oil reservoir 15 can reduce the degree of wear during product operation and further improve the lubrication effect.

[0030] In summary, the present invention, through the design of flexible friction layer 1 and flexible friction layer 2, ensures that when the metal joint is in rotation or swinging conditions, the outer seat sleeve of the metal joint and the outer rolling ball sleeve are in flexible friction contact through the provision of flexible friction layer 1. When the metal joint is in traction or braking conditions, the outer rolling ball sleeve and the spherical surface of the inner limit block are in flexible friction contact through flexible friction layer 2. This ensures that the metal joint of the present invention can achieve flexible friction contact in various operating conditions, thereby avoiding excessive wear and extending the service life of the entire product. In addition, the provision of rubber can also reduce noise and vibration generated by the vehicle body. In addition, by designing the specific structure of the flexible friction layer 1, when the metal joint rotates or swings at a small angle, it is the deformation of the rubber 1 located between the wear-resistant ball sleeve 1 and the outer seat sleeve of the metal joint that bears the pressure. At this time, the wear-resistant ball sleeve 1 and the outer rolling ball sleeve are relatively stationary. Only when the metal joint rotates or swings at a large angle, the acting force exceeds the static friction between the wear-resistant ball sleeve 1 and the outer rolling ball sleeve, the wear-resistant ball sleeve 1 and the outer rolling ball sleeve will move relative to each other to form a friction pair. At this time, the movement of the product is jointly borne by the deformation of the rubber 1 and the friction pair, which greatly improves the service life of the product.

[0031] The term "plurality" in the embodiments refers to "two or more." The above embodiments are intended to illustrate the present invention only and are not intended to limit the present invention. Persons skilled in the art may make various modifications or alterations without departing from the spirit and scope of the present invention. Therefore, all equivalent technical solutions are intended to fall within the scope of protection of the present invention, which is defined by the claims.

Claims

1. A method for designing a friction layer for a metal joint in a low-floor vehicle articulation device, wherein the metal joint comprises a metal joint outer seat, an outer rolling ball sleeve disposed within the metal joint outer seat, and an inner stopper disposed within the outer rolling ball sleeve, wherein the outer rolling ball sleeve and the inner stopper are in spherical contact, and wherein: The flexible friction layer design method is to set a flexible friction layer 1 between the outer seat sleeve of the metal joint and the outer rolling ball sleeve, and set a flexible friction layer 2 between the outer rolling ball sleeve and the spherical surface of the inner limit block; when the inner limit block is locked on the outer seat sleeve of the metal joint by bolts so that the inner limit block, the outer rolling ball sleeve and the outer seat sleeve of the metal joint form a metal joint, the outer rolling ball sleeve and the flexible friction layer 1 are in spherical contact.

2. The friction layer design method according to claim 1, characterized in that: The flexible friction layer includes rubber and wear-resistant ball sleeve. The wear-resistant ball sleeve is bonded to the inside of the outer seat sleeve of the metal joint by vulcanization of the rubber. The wear-resistant ball sleeve is in spherical contact with the outside of the outer rolling ball sleeve.

3. The friction layer design method according to claim 2, characterized in that: The flexible friction layer 2 includes rubber 2 and wear-resistant ball sleeve 2. The wear-resistant ball sleeve 2 is arranged on the inner spherical surface of the outer rolling ball sleeve. The rubber is vulcanized and bonded to the outer spherical surface of the inner limit block. A gap H is left between the rubber 2 and the wear-resistant ball sleeve 2.

4. The friction layer design method according to claim 3, characterized in that: An inlay groove 1 is provided on the inner spherical surface of the outer rolling ball sleeve, and the wear-resistant ball sleeve 2 is embedded in the inlay groove 1, thereby arranging the wear-resistant ball sleeve 2 on the inner spherical surface of the outer rolling ball sleeve.

5. The friction layer design method according to claim 2, 3 or 4, characterized in that: An oil storage groove is provided on the contact spherical surface between the wear-resistant ball sleeve 1 and the outer rolling ball sleeve.

6. The friction layer design method according to claim 2, characterized in that: An upwardly extending shaft column is also provided on the inner spherical surface of the metal joint outer seat sleeve. The shaft column and the metal joint outer seat sleeve are an integrated structure. Rubber 1 includes a spherical rubber body. The spherical rubber body is vulcanized and bonded between the inner spherical surface of the metal joint outer seat sleeve and the outer spherical surface of the wear-resistant ball sleeve 1. One end of the spherical rubber body extends to form a sleeve-shaped rubber body, which is wrapped around the outer circumferential surface of the shaft column.

7. The friction layer design method according to claim 6, characterized in that: A spacer is provided inside the spherical rubber body, and an inlay groove is provided on the side of the spacer; the spacer is first bonded to the outer seat sleeve of the metal joint through rubber vulcanization, and then the wear-resistant ball sleeve is embedded in the inlay groove on the spacer, so that the wear-resistant ball sleeve is vulcanized inside the outer seat sleeve of the metal joint through rubber vulcanization.

8. The friction layer design method according to claim 7, characterized in that: An annular step is provided near the inner top of the outer rolling ball sleeve, an annular groove is provided on the annular step, and a sealing ring is provided in the annular groove; during assembly, a sealing structure is formed by pressing the top plate against the annular step, thereby utilizing the top plate to press and contact the sealing ring.

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