Butterfly valve with bidirectional sealing performance

Abstract

The application is suitable for the technical field of butterfly valves, and provides a butterfly valve with bidirectional sealing performance, which comprises a valve body, a butterfly plate assembly, a valve rod and a valve seat. The butterfly plate assembly comprises a butterfly plate, a sealing ring and a pressing ring. A corrugated pipe is welded between the valve seat and the valve body. Two three-eccentric supporting blocks are arranged between the butterfly plate and the valve body. When the butterfly valve bears reverse medium pressure, the medium pressure acts on the non-pressure balance surface of the valve seat, pushes the valve seat to compress the corrugated pipe to automatically adjust the position, makes up the displacement gap of the butterfly plate assembly, makes the sealing surface tightly contact, and realizes bidirectional sealing. When the medium pressure acts on the butterfly plate in the reverse direction, the butterfly plate assembly has a tendency to displace backward. At this time, the medium pressure acts on the non-pressure balance surface of the valve seat, pushes the valve seat to compress the corrugated pipe, automatically adjusts the position, makes up the displacement gap of the butterfly plate assembly, makes the sealing ring and the valve seat tightly contact, thereby realizing reverse sealing and improving the bidirectional sealing effect of the butterfly valve.

Description

Technical Field

[0001] This invention relates to the field of butterfly valve technology, and more specifically, to a butterfly valve with bidirectional sealing performance. Background Technology

[0002] With the development of new energy and intelligent technology in China, butterfly valve technology has been upgraded from "basic sealing standards" to "high precision, extreme working condition adaptability, and intelligent integration". Domestic substitution is accelerating. Bidirectional metal-sealed butterfly valves adopt double or triple eccentric structures to adapt to bidirectional pressure conditions and are widely used in pipelines for petroleum, chemical, gas, and water treatment.

[0003] like Figure 7 As shown, when existing butterfly valves are subjected to reverse medium pressure, the butterfly plate assembly will shift backward under pressure, causing the sealing surface to separate and resulting in leakage. The bidirectional sealing function is prone to failure. The valve seat usually uses a gasket seal, which is tightened by a three-ring and screw. The gasket seal is unreliable and prone to failure. Moreover, the valve seat cannot be adjusted after compression, resulting in poor bidirectional sealing effect and easy leakage. The screw contacts the valve seat plane, and the valve seat cannot be positioned, which can easily cause displacement, resulting in butterfly valve jamming and leakage. There are no anti-loosening measures at the set screw, which can easily loosen and fall off, potentially blocking the pipeline, jamming the butterfly valve, and causing equipment failure. At high speeds, it can also impact the pipe wall, causing wear or leakage, posing a great safety hazard. Summary of the Invention

[0004] To address the shortcomings of existing technologies, the present invention aims to provide a butterfly valve with bidirectional sealing performance. When the medium pressure acts in the opposite direction on the butterfly plate, the butterfly plate assembly tends to move backward. At this time, the medium pressure acts on the non-pressure balance surface of the valve seat, pushing the valve seat to compress the bellows, automatically adjusting its position, compensating for the displacement gap of the butterfly plate assembly, and keeping the sealing ring in close contact with the valve seat, thereby achieving reverse sealing and improving the bidirectional sealing effect of the butterfly valve.

[0005] To achieve the above objectives, the present invention provides the following technical solution: A butterfly valve with bidirectional sealing performance includes a valve body, a butterfly plate assembly, a valve stem, and a valve seat. The butterfly plate assembly includes a butterfly plate, a sealing ring, and a pressure ring. A valve stem hole is longitudinally penetrating the valve body. The valve stem is rotatably disposed within the valve stem hole and drives the butterfly plate assembly to rotate via a key connection, thereby realizing the opening and closing of the butterfly valve. A bellows is welded between the valve seat and the valve body. One end of the bellows is welded to the valve seat, and the other end is welded to the valve body. Through the elastic deformation of the bellows, the valve seat can move axially within a certain range. Two triple eccentric support blocks are provided between the butterfly plate and the valve body. The triple eccentric support blocks include... The valve assembly includes a first stop block fixed to the upper and lower shaft ends of the butterfly plate and a second stop block fixed in the valve body cavity and adapted to the first stop block. Both the first and second stop blocks are arc-shaped block structures with arc-shaped contact surfaces and different inner radii. When the butterfly valve is subjected to reverse medium pressure, the triple eccentric support stop blocks support the butterfly plate assembly and limit excessive displacement of the butterfly plate assembly. When the butterfly valve is subjected to reverse medium pressure, the medium pressure acts on the non-pressure balance surface of the valve seat, pushing the valve seat to compress the bellows to automatically adjust its position, making up for the displacement gap of the butterfly plate assembly, so that the sealing surfaces are in tight contact and achieving bidirectional sealing.

[0006] The present invention is further configured such that: a three-ring is installed in the groove of the valve body; a plurality of set screws are threaded through the three-ring; and a blind hole is provided on the back of the valve seat to slide with the cylindrical end of the corresponding set screw.

[0007] The invention is further configured such that: a baffle is installed on the outer side of the three-ring; the surface of the baffle has a through hole coaxially arranged with the corresponding set screw; the diameter of the through hole is smaller than the diameter of the set screw, and the set screw can be adjusted by passing a hexagonal wrench through the through hole on the baffle.

[0008] The invention is further configured such that: the baffle is fixed to the valve body by four evenly distributed hexagonal bolts; and a double-eared retaining washer is installed at the lower end of the hexagonal bolts.

[0009] The invention is further configured such that: the triple eccentric support block is welded to the valve body and the butterfly plate, and its eccentric structure includes: the first eccentricity is the eccentricity a between the overall center line of the triple eccentric support block and the center line of the valve body; the second eccentricity is the eccentricity b between the center line of the first block and the center line of the valve stem; and the third eccentricity is the eccentricity c between the center line of the second block and the center line of the valve stem. When the butterfly valve is opened, the first block and the second block are instantly disengaged; when the butterfly valve is closed, the first block and the second block are in line contact along the arc direction.

[0010] The present invention is further configured such that: the sealing ring adopts a gradient hardness structure, and the hardness changes in a gradient from the sealing working surface to the contact surface with the butterfly plate along the thickness direction.

[0011] The present invention is further configured such that the gradient hardness structure of the sealing ring includes: a surface layer, which is the sealing working surface, with a thickness of 10% to 20% and a hardness range of 55 to 60 HRC; a transition layer, with a thickness of 30% to 40% and a hardness range of 45 to 55 HRC; and a base layer, with a thickness of 40% to 50% and a hardness range of 30 to 35 HRC.

[0012] The present invention is further configured such that: an elastic compensation layer is provided between the sealing ring and the butterfly plate; the elastic compensation layer is bonded to both the sealing ring and the butterfly plate through a vulcanization layer.

[0013] The present invention is further configured such that: the elastic compensation layer is an integral structure covering the entire back of the sealing ring; the elastic compensation layer is made of metal rubber, elastic metal foil, high-temperature elastomer or wave spring material.

[0014] The advantages of this invention are: 1. When the medium pressure acts on the front of the butterfly plate, the cylindrical end of the set screw is screwed into the blind hole of the valve seat, which supports and positions the valve seat, prevents the valve seat from rotating or displacing, ensures stable contact of the sealing surface, and improves the stability of the sealing connection between the valve seat and the butterfly plate.

[0015] 2. When the medium pressure acts in the opposite direction on the butterfly plate, the butterfly plate assembly tends to move backward. At this time, the medium pressure acts on the non-pressure balance surface of the valve seat, pushing the valve seat to compress the bellows, automatically adjusting the position, compensating for the displacement gap of the butterfly plate assembly, and keeping the sealing ring in close contact with the valve seat, thereby achieving reverse sealing and improving the bidirectional sealing effect of the butterfly valve.

[0016] 3. In this invention, a bellows is welded between the valve seat and the valve body. The bellows has good elastic deformation ability. Under the action of reverse pressure, the bellows achieves automatic adjustment of the valve seat through compression deformation, keeping the sealing surface in contact. At the same time, the bellows is welded to the valve body and valve seat, with no dynamic sealing points, which can effectively reduce the risk of leakage and improve the sealing reliability.

[0017] 4. When the butterfly valve is opened, due to the eccentric structure design of the triple eccentric support blocks, the first block and the second block disengage instantly, reducing friction and extending service life. When the butterfly valve is closed, the first block and the second block form a line contact along the arc direction, providing mechanical support to the butterfly plate assembly under the action of reverse medium pressure, preventing it from shifting backward and enhancing bidirectional sealing performance.

[0018] 5. The set screw of this invention is installed by a three-ring, with its cylindrical end inserted into the blind hole of the valve seat to achieve precise positioning of the valve seat and prevent rotational displacement; a baffle is provided on the outside of the three-ring, with the diameter of the through hole of the baffle being smaller than the diameter of the set screw to prevent the screw from falling off after loosening; the baffle is fixed by an external hex bolt and is equipped with a double-eared retaining washer to prevent the bolt from loosening and improve the safety and stability of the overall structure. Attached Figure Description

[0019] Figure 1 This is a schematic diagram of the structure of a butterfly valve with bidirectional sealing performance according to the present invention.

[0020] Figure 2 This is a top-view cross-sectional view of the butterfly valve of the present invention.

[0021] Figure 3 For the present invention Figure 2 Enlarged view of region A.

[0022] Figure 4 For the present invention Figure 2 Enlarged view of region B.

[0023] Figure 5 This is a schematic diagram of the valve seat and bellows under the pressure deformation state of the medium in this invention.

[0024] Figure 6 This is a schematic diagram of the sealing ring, elastic compensation layer, and butterfly plate structure of the present invention.

[0025] Figure 7 This is a schematic diagram of the structure of a butterfly valve in the prior art.

[0026] In the diagram: 1. Valve body; 2. Valve stem; 3. Valve seat; 4. Butterfly plate; 5. Sealing ring; 6. Pressure ring; 7. Bellows; 8. Triple eccentric support block; 9. First block; 10. Second block; 11. Triple open ring; 12. Set screw; 13. Blind hole; 14. Baffle; 15. Through hole; 16. External hex bolt; 17. Double-eared retaining washer; 18. Surface layer; 19. Transition layer; 20. Base layer; 21. Elastic compensation layer; 22. Vulcanized layer. Detailed Implementation

[0027] It should be noted that, unless otherwise specified, the embodiments and features described in this application can be combined with each other. The present invention will now be described in detail with reference to the accompanying drawings and embodiments.

[0028] It should be noted that, unless otherwise specified, all technical and scientific terms used in this application have the same meaning as commonly understood by one of ordinary skill in the art to which this application pertains.

[0029] In this invention, unless otherwise stated, the directional terms such as "up" and "down" generally refer to the directions shown in the accompanying drawings, or to the vertical, perpendicular, or gravitational direction; similarly, for ease of understanding and description, "left" and "right" generally refer to the left and right shown in the accompanying drawings; "inner" and "outer" refer to the inner and outer contours of each component itself, but the above directional terms are not intended to limit this invention.

[0030] Example 1, please refer to Figure 1-7 The present invention provides the following technical solutions: A butterfly valve with bidirectional sealing performance specifically includes a valve body 1, a butterfly plate assembly, a valve stem 2, and a valve seat 3; the butterfly plate assembly includes a butterfly plate 4, a sealing ring 5, and a pressure ring 6; a valve stem hole is provided in the valve body 1, which runs longitudinally through the valve body 1; the valve stem 2 is rotatably disposed in the valve stem hole and drives the butterfly plate assembly to rotate through a key connection, thereby realizing the opening and closing of the butterfly valve.

[0031] A bellows 7 is welded between the valve seat 3 and the valve body 1; one end of the bellows 7 is welded to the valve seat 3 and the other end is welded to the valve body 1. Through the elastic deformation of the bellows 7, the valve seat 3 can move axially within a certain range.

[0032] The bellows 7 preferably adopts a multi-layer composite metal bellows structure, which has excellent elastic deformation capacity and fatigue resistance. Through the elastic deformation of the bellows 7, the valve seat 3 can move axially within a certain range to realize the automatic adjustment function. Two triple eccentric support blocks 8 are provided between the butterfly plate 4 and the valve body 1. The triple eccentric support blocks 8 include a first block 9 fixed to the upper and lower shaft ends of the butterfly plate 4 and a second block 10 fixed in the inner cavity of the valve body 1 and adapted to the first block 9. Both the first block 9 and the second block 10 are arc-shaped block structures with arc-shaped contact surfaces and different inner circle radii.

[0033] The first stop 9 and the second stop are both made of wear-resistant alloy material and are fixedly connected to the butterfly plate 4 and the valve body 1 respectively by welding.

[0034] When the butterfly valve is subjected to reverse medium pressure, the triple eccentric support block 8 supports the butterfly plate assembly and restricts excessive displacement of the butterfly plate assembly.

[0035] When the butterfly valve is subjected to reverse medium pressure, the medium pressure acts on the non-pressure balance surface of the valve seat 3, pushing the valve seat 3 to compress the bellows 7 to automatically adjust its position, making up for the displacement gap of the butterfly plate assembly, so that the sealing surfaces are in tight contact and achieving bidirectional sealing.

[0036] Working principle of this embodiment: Positive sealing condition: When the butterfly valve is subjected to positive medium pressure, the medium pressure pushes the butterfly plate assembly, so that the sealing working surface of the sealing ring 5 is in close contact with the valve seat 3, thus achieving positive sealing. At this time, the valve seat 3 maintains a stable position under the support of the bellows 7.

[0037] Reverse sealing condition: When the butterfly valve is subjected to reverse medium pressure, the butterfly plate assembly tends to move backward under the action of medium pressure. At this time, the medium pressure also acts on the non-pressure balance surface of the valve seat 3, pushing the valve seat 3 to compress the bellows 7 and move forward, automatically adjusting the position to make up for the displacement gap of the butterfly plate assembly, so that the sealing ring 5 and the valve seat 3 are in close contact, thereby achieving reverse sealing.

[0038] Meanwhile, the triple eccentric support block 8 plays an auxiliary support role: the first block 9 and the second block 10 form a line contact along the arc direction when the butterfly valve is closed, providing mechanical support for the butterfly plate assembly, preventing it from further shifting backward, and further enhancing the reliability of the bidirectional seal. Pressure fluctuation adaptation: When the medium pressure fluctuates, the bellows 7 automatically adjusts the position of the valve seat 3 through elastic deformation to maintain a constant sealing pressure ratio between the sealing ring 5 and the valve seat 3, ensuring stable sealing performance.

[0039] Example 2, please refer to Figure 1-7 This embodiment two is an improvement on the first embodiment as follows: Specifically, a three-ring 11 is installed in the groove of the inner cavity of the valve body 1; a number of set screws 12 are threaded through the three-ring 11, preferably three, corresponding to the three arc segments of the three-ring 11 respectively; a blind hole 13 is provided on the back of the valve seat 3 to slide with the cylindrical end of the corresponding set screw 12. The blind hole 13 is a non-through structure to ensure the sealing integrity of the valve seat 3.

[0040] A baffle 14 is installed on the outer side of the three-ring 11; a through hole 15 is provided on the surface of the baffle 14, which is coaxial with the corresponding set screw 12; the diameter of the through hole 15 is smaller than the diameter of the set screw 12, and the set screw 12 can be adjusted by passing a hex wrench through the through hole 15 on the baffle 14.

[0041] The baffle 14 is fixed to the valve body 1 by four evenly distributed hex bolts 16; a double-eared retaining washer 17 is installed at the lower end of the hex bolts 16 to effectively prevent the hex bolts 16 from loosening and falling off.

[0042] The triple eccentric support block 8 is welded to the valve body 1 and the butterfly plate 4. Its eccentric structure includes: the first eccentricity is the eccentricity a between the overall center line of the triple eccentric support block 8 and the center line of the valve body 1; the second eccentricity is the eccentricity b between the center line of the first block 9 and the center line of the valve stem 2; and the third eccentricity is the eccentricity c between the center line of the second block 10 and the center line of the valve stem 2. When the butterfly valve is opened, the first block 9 and the second block 10 are instantly disengaged. When the butterfly valve is closed, the first block 9 and the second block 10 are in line contact along the arc direction.

[0043] The three eccentric distances together determine the relative positions of the first stop 9 and the second stop 10 when the butterfly valve is closed, ensuring that the first stop 9 and the second stop 10 can accurately meet and form contact in the closed state, controlling the relative movement trajectory of the first stop 9 and the second stop 10 during the opening process, and achieving instantaneous disengagement.

[0044] Both the first stop 9 and the second stop 10 are arc-shaped block structures with circular arc-shaped contact surfaces. Let the inner radius of the contact surface of the first stop 9 be R1 and the inner radius of the contact surface of the second stop 10 be R2, satisfying R1≠R2. When the radii of curvature of the two arc surfaces are different, the two curved surfaces cannot fit together completely, and the contact method is a line contact along the arc direction.

[0045] The eccentric structure (eccentrics a, b, c) determines the relative position of the first stop 9 and the second stop 10 in space, ensuring that the first stop 9 and the second stop 10 can accurately meet when closed. The difference in inner circle radius (R1≠R2) determines the geometric matching relationship of the contact surfaces of the first stop 9 and the second stop 10, ensuring that a line contact rather than a surface contact is formed along the arc direction when they meet. Since the inner circle radius R1 of the first stop 9 is different from the inner circle radius R2 of the second stop 10 (R1≠R2), the two arc surfaces cannot be completely fitted together, and contact is only formed on a contact line. Under this line contact state along the arc direction, the contact stress is concentrated and the support stiffness is high, which can effectively prevent the butterfly plate assembly from shifting backward under the action of reverse medium pressure. At the same time, the contact area of ​​the line contact along the arc direction is small and the frictional resistance is small, which creates good conditions for subsequent opening operations.

[0046] When the butterfly valve rotates from the closed state to the open state, the butterfly plate 4 drives the first stop block 9 to rotate around the center line of the valve stem 2. Under the action of the eccentric structure (especially eccentric b and eccentric c), the first stop block 9 moves along a specific trajectory. Due to the different inner radii, the first stop block 9 and the second stop block 10 quickly separate, achieving instantaneous disengagement. After the butterfly valve is opened, the two stops are completely out of contact, and there is no frictional resistance during the opening and closing process, which reduces the opening and closing torque.

[0047] When the butterfly valve rotates from the open state to the closed state, the butterfly plate 4 drives the first stop 9 to gradually approach the second stop 10. Under the action of the eccentric structure, the first stop 9 and the second stop 10 meet accurately in the closed position. Due to the different inner radii, the two stops form a line contact along the arc direction at the moment of contact, providing stable mechanical support.

[0048] Working principle of this embodiment two: Valve seat 3 positioning and adjustment: Under positive medium pressure conditions, the cylindrical end of the set screw 12 is inserted into the blind hole 13 of the valve seat 3 to support and position the valve seat 3, prevent the valve seat 3 from rotating and ensure stable contact of the sealing surface; by rotating the set screw 12, the axial position of the valve seat 3 can be finely adjusted to compensate for machining errors and assembly errors.

[0049] Cooperative action under reverse pressure: Under reverse medium pressure, the valve seat 3 moves forward under the elastic action of the bellows 7. At this time, the cylindrical end of the set screw 12 slides in the blind hole 13, which not only ensures the smooth axial movement of the valve seat 3, but also prevents the valve seat 3 from circumferentially deflecting, ensuring uniform contact between the sealing ring 5 and the valve seat 3.

[0050] Anti-loosening safety protection: The baffle 14 achieves a dual function through the cooperation of the through hole 15 and the set screw 12: On the one hand, the through hole 15 allows tools to pass through and adjust the set screw 12; on the other hand, since the diameter of the through hole 15 is smaller than the diameter of the set screw 12, even if the set screw 12 loosens due to vibration, its head cannot pass through the through hole 15 and come out completely, effectively preventing the screw from falling into the pipe and avoiding equipment failure and safety accidents.

[0051] Bolt loosening prevention: The double-eared retaining washer 17 installed at the lower end of the external hex bolt 16 will bend the retaining ear to fit against the bolt head or valve body 1 surface after the bolt is tightened, effectively preventing the bolt from loosening and falling off due to vibration, and ensuring the fixed reliability of the baffle 14.

[0052] Example 3, please refer to Figure 1-7 This third embodiment improves upon the second embodiment as follows: specifically, the sealing ring 5 adopts a gradient hardness structure, with the hardness decreasing gradually from the sealing working surface to the contact surface with the butterfly plate 4 along the thickness direction. This gradient hardness structure is prepared by laser cladding process, specifically including: Surface layer 18: This is the sealing working surface, accounting for 10% to 20% of the total thickness, with a hardness range of 55 to 60 HRC. Surface layer 18 is made of Stellite 6 / 12, WC-Co, or Cr3C2-NiCr hard alloy material, which has excellent wear resistance and anti-scratch properties. It forms a hardness difference pair with valve seat 3, and the main wear occurs on the side of valve seat 3, protecting critical components.

[0053] Transition layer 19: Located between surface layer 18 and substrate layer 20, with a thickness of 30% to 40% and a hardness range of 45 to 55 HRC. Transition layer 19 is prepared layer by layer by adjusting laser cladding parameters or using alloy powders of different hardness. It plays a stress buffering role, effectively dispersing the contact stress borne by surface layer 18 and preventing the hard layer from peeling off due to stress concentration.

[0054] Substrate layer 20: This is the base layer of the sealing ring 5, accounting for 40% to 50% of the total thickness, with a hardness range of 30 to 35 HRC. Substrate layer 20 is made of 17-4PH, 304, or 316L stainless steel, which has high toughness and can absorb medium pressure fluctuations and opening and closing impacts, preventing the sealing ring 5 from brittle fracture. It also undergoes slight plastic deformation during long-term use to compensate for minor wear on the sealing surface.

[0055] The sum of the thicknesses of the surface layer 18, transition layer 19, and substrate layer 20 is 100%.

[0056] An elastic compensation layer 21 is provided between the sealing ring 5 and the butterfly plate 4. The elastic compensation layer 21 is an integral annular structure that covers the entire back of the sealing ring 5, ensuring uniform force distribution in the circumferential direction. The elastic compensation layer 21 is made of metal rubber, elastic metal foil, high-temperature elastomer, or wave spring material, selected according to the operating conditions. Metal rubber: It is made of stainless steel wire woven and pressed into shape, and has a temperature resistance of -200~800℃. It is suitable for high temperature, high pressure and corrosive working conditions. Elastic metal foils, such as beryllium bronze and Inconel foils, have good linear elasticity and are suitable for precision adjustment; High-temperature elastomers: such as fluororubber and perfluoroether rubber, are suitable for medium and low temperature and corrosive working conditions; Wave spring: Disc spring assembly, with a large compensation range and customizable stiffness.

[0057] The elastic compensation layer 21 is bonded and fixed to the sealing ring 5 and the butterfly plate 4 by a vulcanized layer 22. The vulcanized layer 22 uses a high-temperature and medium-resistant vulcanizing adhesive, which can maintain reliable bonding strength under high temperature and high pressure environment, ensuring a firm connection between the elastic compensation layer 21 and the parts on both sides.

[0058] Working principle of this embodiment three: Wear and buffering mechanism of gradient hardness sealing ring 5: During the opening and closing of the butterfly valve, the high-hardness surface layer 18 rubs against the valve seat 3. Due to the hardness difference, the sealing ring 5 itself experiences minimal wear; the main wear occurs on the valve seat 3 side, protecting the difficult-to-replace sealing ring 5. The transition layer 19 gradually diffuses the high contact stress borne by the surface layer 18 to the base layer 20, preventing stress abrupt changes from causing coating peeling. When subjected to media impact and opening / closing impact, the base layer 20 absorbs energy through its high toughness, preventing the sealing ring 5 from shattering. After long-term use, the base layer 20 can undergo slight plastic deformation, automatically compensating for the wear of the sealing surface and extending the service life of the sealing ring 5.

[0059] The adaptive compensation mechanism of the elastic compensation layer: During the assembly of the butterfly valve, the elastic compensation layer 21 compensates for the coaxiality error and flatness error between the butterfly plate 4 and the valve body 1 through elastic deformation, ensuring that the sealing ring 5 and the valve seat 3 are in uniform contact, and reducing the requirements for the machining accuracy of the parts.

[0060] When the medium temperature changes, the valve body 1 and the butterfly plate 4 have different thermal expansion due to their different materials. The elastic compensation layer 21 absorbs the dimensional changes through elastic deformation, preventing interference or gap between the sealing ring 5 and the valve seat 3, and avoiding sealing failure caused by thermal stress.

[0061] When the medium pressure fluctuates, the elastic compensation layer 21 finely adjusts the position of the sealing ring 5 to maintain a constant sealing pressure between the sealing ring 5 and the valve seat 3, ensuring stable sealing performance.

[0062] When the sealing ring 5 or valve seat 3 experiences slight wear, the elastic compensation layer 21 releases its pre-compression, automatically compensating for the wear gap, ensuring that the sealing ring 5 always maintains close contact with the valve seat 3, thus extending the maintenance cycle.

[0063] The synergistic effect of gradient hardness and elastic compensation: The gradient hardness structure solves the wear resistance and impact resistance problems of the sealing ring 5, extending its service life; the elastic compensation layer 21 solves the problems of assembly error, thermal deformation and wear gap compensation, maintaining good contact between the sealing surfaces. The synergistic effect of these two elements enables the butterfly valve to maintain stable and reliable sealing performance even under complex operating conditions.

[0064] Obviously, the embodiments described above are merely some, not all, embodiments of the present invention. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without inventive effort should fall within the scope of protection of the present invention.

[0065] It should be noted that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the exemplary embodiments according to this application. As used herein, the singular form is intended to include the plural form as well, unless the context clearly indicates otherwise. Furthermore, it should be understood that when the terms "comprising" and / or "including" are used in this specification, they indicate the presence of features, steps, operations, devices, components, and / or combinations thereof.

[0066] It should be noted that the terms "first," "second," etc., used in the specification, claims, and accompanying drawings of this application are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that such data can be interchanged where appropriate so that the embodiments of this application described herein can be implemented in sequences other than those illustrated or described herein.

[0067] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

[0068] The above description is merely a preferred embodiment of the present invention. The scope of protection of the present invention is not limited to the above embodiments. All technical solutions falling within the scope of the present invention's concept are within the scope of protection of the present invention. It should be noted that for those skilled in the art, any improvements and modifications made without departing from the principles of the present invention should also be considered within the scope of protection of the present invention.

Claims

1. A butterfly valve with bidirectional sealing performance, comprising a valve body (1), a butterfly plate assembly, a valve stem (2), and a valve seat (3); the butterfly plate assembly comprises a butterfly plate (4), a sealing ring (5), and a pressure ring (6); a valve stem hole is provided in the valve body (1) longitudinally penetrating the valve body (1); the valve stem (2) is rotatably disposed in the valve stem hole and drives the butterfly plate assembly to rotate through a key connection, thereby realizing the opening and closing of the butterfly valve; characterized in that: A bellows (7) is welded between the valve seat (3) and the valve body (1); one end of the bellows (7) is welded to the valve seat (3), and the other end is welded to the valve body (1). Through the elastic deformation of the bellows (7), the valve seat (3) can move axially within a certain range. Two triple eccentric support blocks (8) are provided between the butterfly plate (4) and the valve body (1); the triple eccentric support blocks (8) include a first block (9) fixed at the upper and lower shaft ends of the butterfly plate (4) and a second block (10) fixed in the inner cavity of the valve body (1) and adapted to the first block (9); the first block (9) and the second block (10) are both arc-shaped block structures with arc-shaped contact surfaces and different inner radii; When the butterfly valve is subjected to reverse medium pressure, the triple eccentric support block (8) supports the butterfly plate assembly and restricts the excessive displacement of the butterfly plate assembly; When the butterfly valve is subjected to reverse medium pressure, the medium pressure acts on the non-pressure balance surface of the valve seat (3), pushing the valve seat (3) to compress the bellows (7) to automatically adjust its position, make up for the displacement gap of the butterfly plate assembly, and make the sealing surfaces in close contact to achieve bidirectional sealing.

2. The butterfly valve with bidirectional sealing performance according to claim 1, characterized in that: A three-ring (11) is installed in the groove of the inner cavity of the valve body (1); a number of set screws (12) are threaded through the three-ring (11); a blind hole (13) is provided on the back of the valve seat (3) to slide with the cylindrical end of the corresponding set screw (12).

3. A butterfly valve with bidirectional sealing performance according to claim 2, characterized in that: A baffle (14) is installed on the outside of the three-ring (11); a through hole (15) is provided on the surface of the baffle (14) and is coaxial with the corresponding set screw (12); the diameter of the through hole (15) is smaller than the diameter of the set screw (12).

4. A butterfly valve with bidirectional sealing performance according to claim 3, characterized in that: The baffle (14) is fixed to the valve body (1) by four evenly distributed hexagonal bolts (16); a double-eared stop washer (17) is installed at the lower end of the hexagonal bolts (16).

5. A butterfly valve with bidirectional sealing performance according to claim 4, characterized in that: The triple eccentric support block (8) is welded to the valve body (1) and the butterfly plate (4). Its eccentric structure includes: the first eccentricity is the eccentricity a between the overall center line of the triple eccentric support block (8) and the center line of the valve body (1); the second eccentricity is the eccentricity b between the center line of the first block (9) and the center line of the valve stem (2); and the third eccentricity is the eccentricity c between the center line of the second block (10) and the center line of the valve stem (2). When the butterfly valve is opened, the first block (9) and the second block (10) are disengaged instantaneously. When the butterfly valve is closed, the first block (9) and the second block (10) are in line contact along the arc direction.

6. A butterfly valve with bidirectional sealing performance according to claim 1, characterized in that: The sealing ring (5) adopts a gradient hardness structure, with the hardness changing in a gradient from the sealing working surface to the contact surface with the butterfly plate (4) along the thickness direction.

7. A butterfly valve with bidirectional sealing performance according to claim 6, characterized in that: The gradient hardness structure of the sealing ring includes: The surface layer (18) is a sealing working surface, with a thickness of 10% to 20% and a hardness range of 55 to 60 HRC. The transition layer (19) has a thickness of 30% to 40% and a hardness range of 45 to 55 HRC. The base layer (20) has a thickness of 40% to 50% and a hardness range of 30 to 35 HRC.

8. A butterfly valve with bidirectional sealing performance according to claim 1, characterized in that: An elastic compensation layer (21) is provided between the sealing ring (5) and the butterfly plate (4); the elastic compensation layer (21) is bonded to the sealing ring (5) and the butterfly plate (4) through a vulcanization layer (22).

9. A butterfly valve with bidirectional sealing performance according to claim 8, characterized in that: The elastic compensation layer (21) is an integral structure covering the entire back of the sealing ring (5); the elastic compensation layer (21) is made of metal rubber, elastic metal foil, high temperature elastomer or wave spring material.

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