Metal hard sealing structure of three-eccentric center butterfly valve

Abstract

The utility model relates to a metal hard sealing structure of a three-eccentric center butterfly valve. The metal hard sealing structure comprises a valve body, a valve seat, a valve plate, a metal sealing ring and a valve plate gland, an annular groove is formed in the edge of the outer end face of the valve plate, the metal sealing ring is arranged in the annular groove, and the metal sealing ring is pressed and fixed through the valve plate gland. A metal hard sealing pair is formed between the metal sealing ring and the valve seat, and sealing surfaces between the metal sealing ring and the valve seat are matched conical surfaces; the valve plate is of an asymmetric structure; axial eccentricity b exists between the center line of the valve plate and the center line of the valve shaft, radial eccentricity a exists between the axial middle section of the metal sealing ring and the rotating center of the valve shaft, and an eccentric angle phi exists between the center line of the conical angle of the conical surface and the center line of the valve body. According to the three-eccentric butterfly valve, the size parameters and the material distribution of the valve internals are optimized, so that the structural safety and the sealing performance of the three-eccentric butterfly valve are improved.

Description

Technical Field

[0001] The utility model relates to a triple eccentric butterfly valve, in particular to a metal hard sealing structure of the triple eccentric butterfly valve. Background Art

[0002] The triple-eccentric, hard-seal butterfly valve features an eccentric metal seal structure. Sealing options include metal-to-metal, interchangeable metal-to-metal, and stainless steel and graphite composite plate seals. Actuation options include electric, manual, worm gear, and pneumatic. The disc of a triple-eccentric, hard-seal butterfly valve is installed diametrically within the valve body's pipeline. Within the valve's cylindrical channel, the disc-shaped disc rotates around its axis, with rotation angles ranging from 0° to 90°. When rotated to 0°, the valve is fully closed; when rotated to 90°, the valve is fully open.

[0003] Triple-eccentric hard-seal butterfly valves, featuring wear resistance, high temperature resistance, and corrosion resistance, are gradually replacing shut-off and regulating valves and are widely used in new nuclear power plants, coal chemical plants, and air separation units. Currently, one-third of valve failures worldwide are caused by seal failures, and sealing failure in triple-eccentric butterfly valves remains a pressing technical challenge.

[0004] Under the influence of fluid-structure interaction, valve trims generate significant stress and deformation, significantly affecting the sealing performance of triple-eccentric butterfly valves. The structural shape and dimensional parameters of the valve trim affect its stress distribution. Therefore, it is necessary to develop a metal hard seal structure for triple-eccentric butterfly valves and propose a multi-objective optimization method that targets structural strength and sealing performance while simultaneously improving the valve trim's structural dimensional parameters and material distribution. Summary of the Invention

[0005] The utility model provides a metal hard sealing structure of a triple eccentric butterfly valve, optimizes the size parameters and material distribution of valve trims, thereby improving the structural safety and sealing performance of the triple eccentric butterfly valve.

[0006] In order to achieve the above purpose, the present invention adopts the following technical solutions:

[0007] A metal hard sealing structure of a three-eccentric butterfly valve comprises a valve body, a valve seat and a valve plate; the valve seat is arranged in the valve body, and the valve plate is driven to rotate by the valve shaft; the metal hard sealing structure also comprises a metal sealing ring and a valve plate pressure cover; the valve plate is provided with an annular groove at the edge of the outer end face away from the valve shaft, the metal sealing ring is arranged in the annular groove, the outer edge of the metal sealing ring protrudes from the outer edge of the valve plate, and a valve plate pressure cover is provided on the outer side of the valve plate to press and fix the metal sealing ring; a metal hard sealing pair is formed between the metal sealing ring and the valve seat, and the sealing surface between the metal sealing ring and the valve seat is a matching conical surface; the valve plate is an asymmetric structure; when the butterfly valve is in a fully closed state, the valve shaft, the metal sealing ring and the valve plate pressure cover are arranged in sequence along the liquid flow direction in the valve body, there is an axial eccentricity b between the center line of the valve plate and the center line of the valve shaft, there is a radial eccentricity a between the axial middle section of the metal sealing ring and the rotation center of the valve shaft, and there is an eccentric angle φ between the center line of the cone angle of the conical surface and the center line of the valve body.

[0008] Furthermore, a graphite gasket is provided between the metal sealing ring and the valve plate, and the graphite gasket is provided in a mounting groove provided in the annular groove.

[0009] Furthermore, the valve plate gland and the valve body are connected by a plurality of screws evenly distributed along the circumferential direction.

[0010] Furthermore, viewed from one end close to the valve shaft, the vertical section of the conical surface has two characteristic points along the counterclockwise direction, namely, a large slope characteristic point located at the 0° coordinate, and a small slope characteristic point located at the 180° coordinate; correspondingly, the conical surface within ±45° of the 0° coordinate point is the large slope, and the conical surface within ±45° of the 180° coordinate point is the small slope; the upper conical surface connecting the large slope and the small slope is the upper transition surface, and the lower conical surface connecting the large slope and the small slope is the lower transition surface; the valve shaft is set parallel to the connection direction of the 90° coordinate point to the 270° coordinate point; viewed from above the valve plate, the opening direction of the valve plate is clockwise.

[0011] Furthermore, the asymmetric structure of the valve plate refers to a large slope structure on the side of the valve plate with a larger area bounded by the valve shaft, in which the material evenly transitions from the valve shaft to the edge of the valve plate, and a "small slope + plane" structure on the side of the valve plate with a smaller area bounded by the valve shaft; and corresponds to three valve plate structural parameters, namely the height A of the large slope, the height B of the small slope, and the distance C from the lowest point of the small slope to the center line of the valve shaft.

[0012] Furthermore, the valve plate and the valve shaft are fixedly connected by a plurality of cylindrical pins arranged along the axial direction of the valve shaft, and a sealing packing is provided between the valve shaft and the valve body.

[0013] Compared with the prior art, the beneficial effects of the present invention are:

[0014] 1) The asymmetric valve plate structure obtained through 3D topology optimization is adopted. The valve plate material is rationally distributed on the basis of lightweight design to avoid the problem of uneven stress distribution caused by eccentric valve shaft position and prevent stress concentration.

[0015] 2) The triple-eccentric butterfly valve uses a metal sealing ring and a valve seat to form a sealing structure. There is no interference when the valve is opened and closed, and the metal sealing ring and the valve seat can be separated or contacted instantly, thereby reducing the wear of the sealing surface, improving the sealing reliability, and adapting to fluid media environments with different temperatures;

[0016] 3) The material distribution and structural dimensions of the valve trim are optimized. The maximum equivalent stress of the optimized lightweight valve trim is significantly reduced, and the sealing pressure ratio is within a reasonable range, ensuring long-term and effective sealing performance;

[0017] 4) Through finite element simulation analysis of the optimized triple-eccentric butterfly valve model, it is proved that the stress distribution of the valve internals is reasonable after optimization, the maximum equivalent stress of the metal sealing ring is reduced by 62.86%, meeting the strength requirements; the maximum sealing pressure ratio is reduced by 60.52%, which is less than the allowable sealing pressure ratio, and a continuous circumferential sealing area is formed on the sealing surface, which has a good sealing effect. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 It is a structural schematic diagram of the triple eccentric butterfly valve of the utility model.

[0019] Figure 2 It is a schematic diagram of the metal hard seal structure of the triple eccentric butterfly valve of the utility model.

[0020] Figure 2a yes Figure 2 A partial enlarged view of .

[0021] Figure 3 It is a structural schematic diagram of the metal sealing ring of the utility model.

[0022] Figure 4 This is the evolution diagram of the valve plate 3D topology optimization process described in the present invention.

[0023] Figure 5 This is the flow chart of the 3D topology optimization of the valve plate described in the present invention.

[0024] Figure 6 This is a rendering of the 3D topology optimization of the valve plate of the present invention.

[0025] Figure 7 This is the parameter diagram of the 3D topology optimization valve plate extraction described in the present invention.

[0026] Figure 8 It is a flow chart of the response surface optimization central combination design described in the present invention.

[0027] Figure 9 It is the stress distribution diagram of the main components of the three eccentric butterfly valve before optimization.

[0028] Figure 10 This is the stress distribution diagram of the main components of the optimized triple eccentric butterfly valve.

[0029] Figure 11 It is the sealing pressure distribution diagram of the sealing surface before optimization.

[0030] Figure 12 The sealing pressure distribution diagram of the optimized sealing surface.

[0031] Figure 1 Middle: 1-Bearing 2-Valve shaft 3-Metal sealing ring 4-Valve plate 5-Cylindrical pin 6-Valve plate gland 7-Valve body 8-Sealing packing 9-Graphite gasket DETAILED DESCRIPTION

[0032] The specific embodiments of the present invention will be further described below with reference to the accompanying drawings:

[0033] like Figure 1 As shown, the metal hard sealing structure of the triple eccentric butterfly valve described in the present invention includes a valve body 7, a valve seat and a valve plate 4; the valve seat is arranged in the valve body 7, and the valve plate 4 is driven to rotate by the valve shaft 2; the metal hard sealing structure also includes a metal sealing ring 3 and a valve plate pressure cover 6; the valve plate 4 is provided with an annular groove on the edge of the outer end surface away from the valve shaft 2, and the metal sealing ring 3 is arranged in the annular groove, and the outer edge of the metal sealing ring 3 protrudes from the outer edge of the valve plate 4, and a valve plate pressure cover 6 is provided on the outer side of the valve plate 4 to press and fix the metal sealing ring 3; the metal sealing ring 3 and A metal hard sealing pair is formed between the valve seats, and the sealing surface between the metal sealing ring 3 and the valve seat is a matching conical surface; the valve plate 4 is an asymmetric structure; when the butterfly valve is in a fully closed state, the valve shaft 2, the metal sealing ring 3 and the valve plate gland 6 are arranged in sequence along the liquid flow direction in the valve body 7, there is an axial eccentricity b between the center line of the valve plate 4 and the center line of the valve shaft 2, there is a radial eccentricity a between the axial middle section of the metal sealing ring 3 and the rotation center of the valve shaft 2, and there is an eccentric angle φ between the cone angle center line of the conical surface and the center line of the valve body 7.

[0034] Furthermore, a graphite gasket 9 is provided between the metal sealing ring 3 and the valve plate 4 , and the graphite gasket 9 is provided in a mounting groove provided in the annular groove.

[0035] Furthermore, the valve plate gland 6 and the valve body 7 are connected by a plurality of screws evenly distributed along the circumferential direction.

[0036] Furthermore, viewed from the end close to the valve shaft 2, the vertical section of the conical surface has two characteristic points along the counterclockwise direction, namely, the large slope characteristic point located at the 0° coordinate, and the small slope characteristic point located at the 180° coordinate; correspondingly, the conical surface within ±45° of the 0° coordinate point is the large slope, and the conical surface within ±45° of the 180° coordinate point is the small slope; the upper conical surface connecting the large slope and the small slope is the upper transition surface, and the lower conical surface connecting the large slope and the small slope is the lower transition surface; the valve shaft is set parallel to the connection direction of the 90° coordinate point to the 270° coordinate point; viewed from above the valve plate 4, the opening direction of the valve plate 4 is clockwise.

[0037] Furthermore, the asymmetric structure of the valve plate 4 refers to a large slope structure on the side of the valve plate 4 with a larger area bounded by the valve shaft 2, in which the material uniformly transitions from the valve shaft to the edge of the valve plate, and a "small slope + plane" structure on the side of the valve plate 4 with a smaller area bounded by the valve shaft 2; and corresponds to three valve plate structural parameters, namely the height A of the large slope, the height B of the small slope, and the distance C from the lowest point of the small slope to the center line of the valve shaft.

[0038] Furthermore, the valve plate 4 and the valve shaft 2 are fixedly connected via a plurality of cylindrical pins 5 arranged axially along the valve shaft 2 , and a sealing packing 8 is provided between the valve shaft 2 and the valve body 7 .

[0039] The optimization design process of the metal hard seal structure of the triple eccentric butterfly valve described in this utility model is as follows:

[0040] Step 1: 3D topology optimization of the valve plate;

[0041] 1) Establish the initial finite element model of the triple-eccentric butterfly valve, divide the mesh into hexahedron and tetrahedron hybrids, and encrypt the mesh near the sealing surface; determine the number of meshes to be divided through finite element mesh independence experiments;

[0042] 2) With the maximum equivalent stress of the valve plate not exceeding the allowable stress of its material as the constraint condition, the optimized area and non-optimized area of the valve plate are set; the boundary conditions including the flange end faces of the three-eccentric butterfly valve being fixed and the valve shaft being allowed to rotate are set, and the positive fluid pressure is set as the load;

[0043] 3) Perform finite element simulation on the equivalent stress of the valve plate, take lightweighting of the valve plate as the optimization goal, and perform topological optimization on the valve plate. After multiple iterations, determine the most reasonable valve plate material distribution scheme;

[0044] In the second step, the valve plate after 3D topology optimization is smoothed, the parameters affecting the strength of the valve plate are simplified, and the three shape and size characteristic parameters determined after the valve plate material distribution are used as variables to participate in the next stage of response surface optimization;

[0045] Step 3: The equivalent stress distribution of the triple-eccentric butterfly valve trim and the sealing pressure ratio on the sealing surface are used as indicators to evaluate the safety of the sealing structure and the sealing performance. The central composite design method of the response surface methodology is used to obtain the optimal parameter matching scheme including the valve plate structural parameters, valve shaft diameter, and valve seat thickness, with the maximum equivalent stress and the maximum sealing pressure ratio on the sealing surface as the response values.

[0046] Step 4: Use finite element simulation analysis to verify the equivalent stress distribution of valve trim and the sealing pressure ratio on the sealing surface of the pre-optimization model and the post-optimization model.

[0047] Furthermore, the step three specifically includes the following process:

[0048] 1) Set the three shape and size characteristic parameters A, B, and C after topology optimization, the valve shaft diameter D, and the sealing surface width E as the optimized design parameter variables; set the maximum equivalent stress Y of the valve trim and the maximum sealing specific pressure X on the sealing surface as the multi-objective response values;

[0049] 2) Carry out single-factor experiments to preliminarily determine the value range of design parameter variables;

[0050] 3) Using finite element simulation to provide experimental data samples, Design-Expert software was used for experimental design and data analysis. The central composite design method of the response surface methodology was used, and the steepest climb method was used to select new center points and directions within the experimental area to guide the selection of experimental points.

[0051] 4) The second-order design model is used to accurately approximate the optimal value of the response surface within the set investigation range, and the interaction terms and quadratic terms that have no significant impact on the response value are eliminated to obtain the optimal parameter matching solution.

[0052] The metal seal structure of a triple-eccentric butterfly valve described in this utility model includes a valve body, a metal sealing ring, a graphite gasket, a valve plate, a valve shaft (supported by a bearing 1), and a valve plate gland. The valve plate and the valve plate gland compress and secure the metal sealing ring, forming a metal seal pair between the metal sealing ring and the valve seat within the valve body. The valve shaft, driven by an actuator, rotates the valve plate and metal sealing ring, creating different angles of opening.

[0053] The metal hard sealing structure of a three-eccentric butterfly valve described in the utility model has a valve plate that has undergone 3D topology optimization. The valve plate has an asymmetric structure. The valve plate material is reasonably distributed on the basis of realizing a lightweight design of the valve plate, effectively solving the problem of uneven stress distribution caused by the eccentric position of the valve shaft, preventing stress concentration, and reducing the maximum equivalent stress by approximately 53.63%.

[0054] When the triple eccentric butterfly valve is closed, due to the area difference between the valve plate and the valve shaft on both sides, a closing torque is generated under the action of the fluid medium pressure, thereby forming a sealing pressure ratio on the sealing surface, thereby realizing the automatic closing of the triple eccentric butterfly valve.

[0055] The valve plate has an installation groove a on the side of the contact surface with the metal sealing ring. A graphite gasket is placed in the installation groove to prevent leakage on the contact side between the metal sealing ring and the valve plate, which can meet the sealing requirements of high-temperature fluid media.

[0056] The valve plate and the valve plate cover are preferably connected by screws, which fix the metal sealing ring and facilitate the removal and replacement of the metal sealing ring after pressure damage on the sealing surface. There is no need to replace the valve plate as a whole, which reduces maintenance costs while ensuring sealing reliability.

[0057] The metal sealing ring's sealing surface is conical and consists of four areas: a large bevel, a small bevel, an upper transition surface, and a lower transition surface. When the valve is opened or closed, the metal sealing ring and valve seat momentarily separate or contact, minimizing wear on the sealing surface and improving sealing reliability.

[0058] The following embodiments are implemented based on the technical solution of the present utility model, and provide detailed implementation methods and specific operating processes, but the protection scope of the present utility model is not limited to the following embodiments.

[0059] [Example]

[0060] In this embodiment, the metal hard seal structure of the triple eccentric butterfly valve Figure 1 、 Figure 2 and Figure 2a As shown in the figure, it consists of a valve body (with a built-in valve seat), a valve plate, a metal sealing ring, a valve plate gland, and a graphite gasket. The valve shaft drives the valve plate to rotate within the valve body, forming a maximum 90° opening. The metal sealing ring is fixed between the valve plate and the valve plate gland and is fixed by multiple screws evenly distributed around the circumference. A metal hard sealing pair with a conical surface is formed between the metal sealing ring and the valve seat. Under the action of a certain external torque, a sealing specific pressure is formed on the sealing surface to achieve a reliable seal. An installation groove is provided on the contact surface between the valve plate and the metal sealing ring, and a graphite gasket is placed in the installation groove to achieve effective sealing on the contact side of the valve plate and the metal sealing ring.

[0061] There is an axial eccentricity b between the center line of the valve plate and the center line of the valve shaft, a radial eccentricity a between the axial middle section of the metal sealing ring and the rotation center of the valve shaft, and an eccentricity angle φ between the center line of the cone angle of the conical surface and the center line of the valve body. The above three parameters are the three eccentricity parameters. The semi-cone angle of the sealing surface is β (such as Figure 2 shown), Figure 2 The valve plate is shown in the closed state.

[0062] The sealing surface between the metal sealing ring and the valve seat (such as Figure 2aAs shown) is a matching conical surface, such as Figure 3 As shown in the figure, the outer surface of the metal sealing ring can be divided into four curved surface areas: a large inclined surface near the 0° coordinate, a small inclined surface near the 180° coordinate, an upper transition surface near the 90° coordinate, and a lower transition surface near the 270° coordinate. The valve axis is parallel to the line connecting the 90° and 270° coordinate points.

[0063] The conical surface allows for different sealing conditions in each area. This eliminates interference between valve trim components when the valve is opened or closed, and allows the metal sealing ring and valve seat to instantly separate or contact, minimizing wear on the sealing surface and improving sealing reliability.

[0064] In this embodiment, the optimization design process of the metal hard seal structure of the triple eccentric butterfly valve is as follows:

[0065] 1) Perform 3D topology optimization on the valve plate. Figure 5 As shown in the figure, based on the finite element simulation analysis, the initial finite element model of the valve plate is established, the hexahedron and tetrahedron mixed grid is divided, and the grid near the sealing surface is encrypted. The number of divided grids is determined through the finite element grid independence experiment.

[0066] The maximum equivalent stress of the valve plate does not exceed the allowable stress of its material as a constraint condition, and the optimization area and non-optimization area of the valve plate are set; the boundary conditions such as the flange end faces of the three-eccentric butterfly valve are fixed and the valve shaft is allowed to rotate are set; the positive fluid pressure is set to a load of 4MPa; based on the finite element simulation calculation of the equivalent stress of the valve plate, the valve plate is topologically optimized with the lightweight design of the valve plate as the optimization goal. After multiple iterations (such as Figure 4 As shown), the material distribution of the valve plate is reasonably distributed.

[0067] The valve plate after 3D topology optimization (the valve plate before and after optimization is as follows Figure 6 The three valve plate structural parameters A, B, and C (shown as Figure 7 These three valve plate structural parameters are also the main fixed dimensions of material distribution and will be involved in the next stage of response surface optimization.

[0068] 2) The central combination design method of the response surface methodology is adopted. Taking the working condition of 4 MPa forward medium pressure as an example, the response surface optimization central combination method is used to construct the functional relationship between the two response values of the maximum equivalent stress Y of the valve trim and the maximum sealing pressure X of the sealing surface and the five parameters (A, B, C, three valve plate structural parameters after topology optimization), the valve shaft diameter D, and the sealing surface width E. A regression model of the five parameters is established to obtain the optimal structural parameter combination of the butterfly valve.

[0069] Conduct a single-factor experiment to analyze the effect of a certain parameter change on the maximum equivalent stress Y of the valve trim and the maximum sealing pressure ratio of the sealing surface, while keeping other parameters unchanged. Then select the value range of the design parameter variable.

[0070] The central composite design method of the response surface method is to use finite element simulation experiments to provide experimental data samples, and use Design-Expert software to perform professional experimental design and data analysis. The simulation process is as follows: Figure 8 shown.

[0071] By using the second-order design model, the optimal value of the response surface is accurately approximated within a smaller investigation range, and some interaction terms and quadratic terms that have no significant effect on the response value are eliminated. The maximum equivalent stress and maximum sealing pressure are obtained after regression fitting, which are equations (1) and (2):

[0072] X=1643.98-3.22396A+1.96378B-7.56814C-8.59106D-41.0965E+0.031391AD-

[0073] 0.0694744BD+0.0497446CD+0.323856DE+0.0114375A 2 +0.0542528B 2 +

[0074] 0.0133643C 2 -0.0403794D 2 +0.165746E 2 .

[0075] Formula (1)

[0076] Y=2629.61+0.163983A+4.77736B-12.9861C-10.4327D-83.8137E-0.0927872BD+

[0077] 0.0716765CD+0.0400125CE+0.620025DE+0.0362728B 2 +0.0228378C 2 -

[0078] 0.089871D 2 +0.404599E 2 .

[0079] Formula (2)

[0080] In order to verify the structural safety and sealing performance of the triple eccentric butterfly valve after parameter optimization, the equivalent stress of the main valve internal components was simulated and compared under the same working conditions according to the structural parameter models before and after optimization. Figure 9 and Figure 10 As shown in the figure, before optimization, the maximum equivalent stresses of the valve plate, valve shaft, and metal sealing ring were all greater than the allowable stress of their materials. After optimization, however, the maximum equivalent stresses of these components were all less than the allowable stress of their materials, meeting the strength requirements. Specifically, the maximum equivalent stress of the metal sealing ring was reduced by 62.86%.

[0081] Under the same working conditions, the sealing pressure ratios of the sealing surfaces before and after optimization are simulated and compared. Figure 11 and Figure 12 As shown in the figure, before optimization, the sealing pressure on the sealing surface met short-term sealing requirements, but its value exceeded the allowable sealing pressure, resulting in pressure loss and failing to meet long-term sealing reliability requirements. After optimization, the maximum sealing pressure on the sealing surface decreased by 60.52%, now below the allowable sealing pressure. Furthermore, a continuous circumferential sealing area was formed on the sealing surface, demonstrating excellent sealing performance.

[0082] Conclusion: The metal hard sealing structure of the three-eccentric butterfly valve described in this utility model has good structural safety and sealing performance. On the basis of realizing the lightweight design of the valve trim, the material distribution of the valve trim is optimized to obtain the optimal structural parameter combination, thereby achieving the purpose of multi-objective optimization of structural strength and sealing performance.

[0083] The above is only a preferred specific implementation method of the present invention, but the protection scope of the present invention is not limited to this. Any technician familiar with the technical field within the technical scope disclosed by the present invention can make equivalent replacements or changes based on the technical solution and inventive concept of the present invention, which should be covered by the protection scope of the present invention.

Claims

1. A metal hard seal structure of a triple eccentric butterfly valve, comprising a valve body, a valve seat and a valve plate; the valve seat is arranged in the valve body, and the valve plate is driven to rotate by the valve shaft; characterized in that: The metal hard sealing structure also includes a metal sealing ring and a valve plate pressure cover; the valve plate has an annular groove on the edge of the outer end face away from the valve shaft, the metal sealing ring is arranged in the annular groove, the outer edge of the metal sealing ring protrudes from the outer edge of the valve plate, and a valve plate pressure cover is provided on the outer side of the valve plate to press and fix the metal sealing ring; a metal hard sealing pair is formed between the metal sealing ring and the valve seat, and the sealing surface between the metal sealing ring and the valve seat is a matching conical surface; the valve plate is an asymmetric structure; when the butterfly valve is in a fully closed state, the valve shaft, the metal sealing ring and the valve plate pressure cover are arranged in sequence along the direction of liquid flow in the valve body, there is an axial eccentricity b between the center line of the valve plate and the center line of the valve shaft, there is a radial eccentricity a between the axial middle section of the metal sealing ring and the rotation center of the valve shaft, and there is an eccentric angle φ between the center line of the cone angle of the conical surface and the center line of the valve body.

2. The metal hard seal structure of a triple eccentric butterfly valve according to claim 1 is characterized in that: A graphite gasket is provided between the metal sealing ring and the valve plate, and the graphite gasket is provided in a mounting groove provided in the annular groove.

3. The metal hard seal structure of a triple eccentric butterfly valve according to claim 1, characterized in that: The valve plate gland and the valve body are connected by a plurality of screws evenly distributed along the circumference.

4. The metal hard seal structure of a triple eccentric butterfly valve according to claim 1, characterized in that: Viewed from one end close to the valve shaft, the vertical section of the conical surface has two characteristic points along the counterclockwise direction, namely, the large slope characteristic point located at the 0° coordinate, and the small slope characteristic point located at the 180° coordinate; correspondingly, the conical surface within ±45° of the 0° coordinate point is the large slope, and the conical surface within ±45° of the 180° coordinate point is the small slope; the upper conical surface connecting the large slope and the small slope is the upper transition surface, and the lower conical surface connecting the large slope and the small slope is the lower transition surface; the valve shaft is set parallel to the connection direction of the 90° coordinate point to the 270° coordinate point; viewed from above the valve plate, the opening direction of the valve plate is clockwise.

5. A metal hard seal structure of a triple eccentric butterfly valve according to claim 1 or 4, characterized in that: The asymmetric structure of the valve plate refers to a large slope structure on the side of the valve plate with a larger area bounded by the valve shaft, in which the material uniformly transitions from the valve shaft to the edge of the valve plate, and a "small slope + plane" structure on the side of the valve plate with a smaller area bounded by the valve shaft; and corresponds to three valve plate structural parameters, namely the height A of the large slope, the height B of the small slope, and the distance C from the lowest point of the small slope to the center line of the valve shaft.

6. The metal hard seal structure of a triple eccentric butterfly valve according to claim 1, characterized in that: The valve plate and the valve shaft are fixedly connected by a plurality of cylindrical pins arranged along the axial direction of the valve shaft, and a sealing filler is arranged between the valve shaft and the valve body.

Images