Low-temperature-resistant butterfly valve body and production process thereof

Abstract

The invention discloses a low-temperature-resistant butterfly valve body and a production process thereof.The low-temperature-resistant butterfly valve body comprises a valve control base, a support, a placement seat, a valve body flange and a valve seat, a valve rod is arranged on the valve control base, the interior of the valve seat is hollow, an annular air bag is arranged in the valve seat, and the valve body flange is arranged on the support; and a rotary air exhaust part is arranged on the valve rod. The invention discloses a production process of a low-temperature-resistant butterfly valve body. The production process comprises the following steps of material preparation, part machining, assembly assembling, overall assembling and debugging, and surface treatment and protection. By arranging the rotary air exhaust part, the rotary air exhaust part synchronously acts along with the valve rod in the opening and closing process of the valve plate, when the valve plate is opened, the air exhaust part exhausts air in the annular air bag of the valve seat, the air bag contracts to enlarge the inner diameter of the valve seat, and contact friction with the valve plate is reduced; and during closing, the air exhaust part runs reversely, and stored air is injected into the air bag, so that the air bag is expanded to be tightly attached to the valve plate.

Description

Technical Field

[0001] The present invention relates to the technical field of valve bodies, and in particular to a low-temperature resistant butterfly valve body and a production process thereof. Background Art

[0002] Cryogenic fluid technology is increasingly being used in modern industry. Applications such as the storage and transportation of liquefied natural gas (LNG), cryogenic air separation, and cryogenic chemical reactions all require precise control of the flow of cryogenic media. As a key component in fluid control systems, the performance of butterfly valves in cryogenic environments directly impacts the safety and reliability of the entire system.

[0003] For the current low-temperature resistant butterfly valve, the patent number "CN113738892B" discloses a low-temperature resistant butterfly valve body and its production process. By improving the basic structure of the valve body, flange, upper valve shaft seat and lower valve shaft seat, the inner wall of the valve body is provided with an internal low-temperature resistant structure, and the outer wall of the valve body is provided with an external low-temperature resistant structure. The internal low-temperature resistant structure cooperates with the external low-temperature resistant structure to provide good insulation and sealing for the valve body. However, during the opening and closing process of the butterfly valve, the valve plate rotates with the valve stem as the axis. Each time it is opened and closed, the valve plate will frequently and closely contact and squeeze with the valve seat. Due to the fluid pressure and the shear force generated by the rotation of the valve plate, the sealing ring inside the valve seat is continuously subjected to friction and impact, and obvious scratches, grooves and other wear marks will appear on the surface of the sealing ring. As the number of uses increases, the wear of the sealing ring gradually accumulates, resulting in the continuous increase in the sealing gap between the sealing ring and the valve plate, causing medium leakage problems.

[0004] Based on this, the present application proposes a low-temperature resistant butterfly valve body and a production process thereof. Summary of the Invention

[0005] The purpose of the present invention is to solve the shortcomings of the prior art and to propose a low-temperature resistant butterfly valve body and a production process thereof.

[0006] In order to achieve the above object, the present invention adopts the following technical solutions: A low-temperature resistant butterfly valve body, comprising a valve control base, a bracket, a placement seat, a valve body flange, and a valve seat; a valve stem is provided on the valve control base; the interior of the valve seat is hollow, and an annular airbag is provided inside the valve seat; a rotary air pumping unit is provided on the valve stem, and the rotary air pumping unit is composed of a rotating member and an air pumping member; the rotating member is arranged in linkage with the valve stem and rotates synchronously with the rotation of the valve stem; the air pumping unit is transmission-connected to the rotating member, and generates negative pressure under the drive of the rotating member, which is used to extract and store air inside the annular airbag; The placement seat is provided with a packing pressing portion, which is composed of a packing member and a pressing member. The packing member is used to fill the sealed space in the placement seat. The pressing member cooperates with the rotating member to apply pressure to the packing member. A valve plate is provided on the valve stem, and swingable spoilers are symmetrically provided on the upstream and downstream surfaces of the valve plate. The spoilers are continuously swung by the flow of water, thereby changing the flow direction of the fluid and disturbing the water.

[0007] Preferably, the bracket is arranged below the valve control base and is fixed to the valve control base by bolts; The placement seat is coaxially arranged directly below the bracket, and the two are axially positioned by a guide column; The valve body flange is arranged below the placement seat, and a sealing groove is provided on the flange surface thereof, which can be directly connected to the corresponding flange surface of the external connection pipe by bolts to form a fluid channel; The valve seat is embedded in the inner wall of the valve body flange, and the valve seat sealing surface is perpendicular to the flow channel center axis of the valve body flange.

[0008] Preferably, the placement seat is used to install the packing pressing part, and the pressure adjustment of the packing is achieved through the cooperation of the pressing part and the rotating part, thereby forming a dynamic sealing protection for the valve stem penetration.

[0009] Preferably, the annular airbag inside the valve seat is used to be filled with a sealing medium, and the internal air is extracted by rotating the air extraction part to achieve expansion and deformation of the airbag, thereby enhancing the sealing fit between the valve seat and the valve plate.

[0010] Preferably, when the rotary air pumping part is reset, it simultaneously drives the packing pressing part to reset, so that the pressure of the packing piece is restored to the initial sealing state.

[0011] Preferably, the flow-disturbing portion generates periodic swings due to the force of the water flow, thereby changing the flow direction of the fluid and forming a flow-disturbing effect.

[0012] A production process for a low-temperature resistant butterfly valve body comprises the following steps: Material preparation: Low-temperature toughness alloy steel is used to prepare the valve control base, bracket, placement seat, valve body flange and valve seat; duplex stainless steel is used to prepare the valve plate; fluororubber, aramid fiber and stainless steel wire mesh are used to prepare the annular airbag; Component processing: CNC machining is performed on the sealing groove of the valve body flange and the valve seat mounting hole, keyways are machined at the matching parts of the valve stem and the rotating part, and CNC milling is used to machine the spiral annular groove of the packing pressure part; Component assembly: The valve seat cooled by liquid nitrogen is heat-fitted into the valve body flange, and hydraulic assembly is used to make the crank and valve stem interference fit, and the pressing piece and the packing placement groove adopt clearance fit; Overall assembly and commissioning: Install the bracket, placement seat, and valve body flange in sequence, and conduct valve plate opening and closing tests, pressure tests, and sealing performance tests at a low temperature of -196°C; Surface treatment and protection: The valve body is sprayed with low-temperature anti-corrosion coating, and the exposed part of the valve stem is plated with nickel-phosphorus alloy.

[0013] The present invention has the following beneficial effects: 1. By setting up a rotary pumping unit, the rotary pumping unit moves synchronously with the valve stem during the opening and closing process of the valve disc: when opening, the pumping unit extracts the gas in the annular airbag of the valve seat, and the airbag contracts to expand the inner diameter of the valve seat, reducing the contact friction with the valve disc; when closing, the pumping unit runs in the reverse direction, injecting the stored gas into the airbag, causing it to expand and fit tightly against the valve disc, thereby enhancing the sealing performance.

[0014] 2. Through the synchronous action of the packing pressing part and the rotating pumping part, increasing pressure is applied to the packing during the opening process of the valve disc. The pressure decreases when the valve disc is closed, realizing dynamic sealing protection of the valve stem penetration point and reducing the risk of leakage in low temperature environment.

[0015] 3. The flow disturbance is formed by the fluid impact and the balanced swing of the torsion spring through the flow spoiler, which changes the flow direction, disperses the impact force, reduces cavitation and extends the life of the valve. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 This is a schematic diagram of the overall structure of a low-temperature resistant butterfly valve body proposed by the present invention; Figure 2 This is a schematic cross-sectional structural diagram of some parts of a low-temperature resistant butterfly valve body proposed by the present invention; Figure 3 This is a schematic diagram of the connection structure between the rotary pumping part and the valve stem, bracket, placement seat and other parts in the present invention; Figure 4 Schematic diagram of the connection structure between the rotary pumping part and the valve seat in the present invention; Figure 5 Schematic diagram of the structure of the rotary pumping unit in the present invention; Figure 6 Schematic diagram of the structure of the valve stem and the spoiler in the present invention; Figure 7 for Figure 6 A in the middle is an enlarged structural diagram; Figure 8 It is a schematic diagram of the cross-sectional structure of the tablet in the present invention.

[0017] In the figure: 1. Valve control base; 2. Valve stem; 21. Crank; 22. Hinge block; 23. Piston rod; 24. Sealing tube; 25. Suction tube; 26. Annular airbag; 3. Bracket; 4. Placement seat; 41. Packing placement groove; 42. Packing; 43. Pressing piece; 44. Annular groove; 45. Protruding rod; 5. Valve body flange; 6. Valve seat; 7. Valve plate; 71. Connecting plate; 72. Rotating rod; 73. Torsion spring; 74. Guide plate. DETAILED DESCRIPTION

[0018] The technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, rather than all the embodiments.

[0019] A production process for a low-temperature resistant butterfly valve body comprises the following steps: Material preparation: Low-temperature toughness alloy steel is used to prepare the valve control base, bracket, placement seat, valve body flange and valve seat; duplex stainless steel is used to prepare the valve plate; fluororubber, basalt fiber and pure titanium wire mesh are used to prepare the annular airbag; Among them, the low-temperature toughness alloy steel used for the valve control base needs to be deep-cold treated at -70℃ for 2 hours to eliminate internal stress; the surface of the duplex stainless steel valve plate is supersonic sprayed with 0.25mm tungsten carbide coating with a hardness of HV1300; the annular airbag adopts a three-layer composite structure, the inner layer of fluorosilicone rubber is vulcanized at -55℃, the middle layer is reinforced with basalt fiber, and the outer layer is protected by pure titanium wire mesh.

[0020] Component processing: CNC machining of the sealing groove of the valve body flange and the valve seat mounting hole, keyway machining of the matching part between the valve stem and the rotating part, and CNC milling of the annular groove in the packing pressure part; The mounting holes of the dual-drive system in the valve-controlled base are machined using five-axis linkage, with the coaxiality controlled at ≤0.02mm; the roughness of the assembly surface of the planetary gearbox reduction mechanism is Ra≤0.8μm; the annular groove in the lower pressure part of the packing is CNC milled, with a lead angle tolerance of ±0.5°; the groove depth of the valve body flange sealing groove is 3mm, the surface roughness is Ra≤1.6μm, and the cylindricity of the valve seat mounting hole is ≤0.02mm.

[0021] Component assembly: The valve seat cooled by liquid nitrogen is heat-fitted into the valve body flange, and hydraulic assembly is used to make the crank and valve stem interference fit, and the pressing piece and the packing placement groove adopt clearance fit; The electric mode components are assembled with low-temperature grease with an operating temperature range of -60°C to +120°C, and the air gap of the electromagnetic clutch is precisely adjusted to 0.3-0.5mm. After the electric components are assembled, the manual gear reducer is tested to control the transmission noise to ≤65dB to meet the low-noise operation requirements. Subsequently, the piston rod and the sealing tube of the rotary pumping part are ground and matched, and the straightness error is strictly controlled to ≤0.01mm / m to ensure the stability and efficiency of the pumping action. Finally, the valve seat is cooled to -196°C with liquid nitrogen and then embedded in the valve body flange using a heat-fitting process to control the interference to 0.1-0.15mm. After assembly, a helium mass spectrometer is used to detect leaks to ensure that the leakage rate is ≤1×10⁻ 9 mbar・L / s, achieving high sealing performance requirements.

[0022] Overall assembly and commissioning: Install the bracket, placement seat, and valve body flange in sequence, and conduct valve plate opening and closing tests, pressure tests, and sealing performance tests at a low temperature of -196°C; The electric drive was tested at a torque of 300 N·m to ensure stable power output. The system then switched to manual drive to verify operational reliability at a torque of 150 N·m. The device was then placed in an extremely low-temperature environment of -196°C and subjected to 500 alternating switching tests between electric and manual modes. During this process, the response of the electromagnetic clutch was monitored, with a response time requirement of less than 0.5 seconds. After the mode switching test, the valve plate was tested for opening and closing performance to ensure that the operating torque remained within a reasonable range of ±10% of the design value. Finally, to verify sealing performance, a pressure test was conducted at 1.5 times the nominal pressure for 5 minutes to ensure no leakage. Subsequently, a 0.6 MPa air pressure condition was used to strictly control seal leakage to less than 0.1 ml / min, fully ensuring the safety and stability of the butterfly valve under complex operating conditions.

[0023] Surface treatment and protection: The valve body is sprayed with low-temperature anti-corrosion coating, and the exposed part of the valve stem is plated with nickel-phosphorus alloy; The valve control base is first sandblasted to achieve a surface roughness of Ra12.5-25μm to enhance coating adhesion, and then sprayed with a 200μm thick low-temperature anti-corrosion coating. The corrosion resistance is ensured by a 1000-hour salt spray test. The valve stem is plated with a nickel-phosphorus alloy layer and then aged at 200℃ for 1 hour to increase the hardness to above HV550, enhancing wear and corrosion resistance. The surface of the spoiler guide plate is plated with a 0.02mm thick hard chromium layer. The high hardness of hard chromium enhances the resistance to fluid erosion and ensures the long-term stable operation of each component under complex working conditions. Example 1:

[0024] Reference Figures 1 to 5A low-temperature resistant butterfly valve body includes a valve control base 1, and the dual drive system in the valve control base 1 switches the working mode through an electromagnetic clutch: the electric mode includes a DC servo motor, a controller, a reduction mechanism, an absolute encoder, an electromagnetic brake, etc. The controller receives instructions from the upper computer and drives the DC servo motor to operate. After the planetary gearbox reduces the speed, it drives the valve stem 2 to rotate. The absolute encoder provides real-time feedback on the valve position to form a closed-loop control. The electromagnetic brake locks the valve stem 2 after it is in place. The manual mode includes components such as a handwheel and a gear reduction box. The operating handwheel is driven by the gear reduction box, and the clutch automatically disengages the motor drive chain. The handwheel torque is directly transmitted to the valve stem 2 through the spline shaft. The overload protection clutch prevents excessive operating force. The valve control base 1 belongs to the existing technology in this field, and the internal structure of the valve control base 1 belongs to one of the existing technologies. It only includes and is not unique. The specific selection needs to be based on actual conditions, so it will not be described in detail.

[0025] The bracket 3, the placement seat 4, the valve body flange 5 and the valve seat 6, the bracket 3 is arranged below the valve control base 1 and is fixed to the valve control base 1 by bolts, the placement seat 4 is coaxially arranged directly below the bracket 3, and the two are axially positioned by a guide column; the valve body flange 5 is arranged below the placement seat 4, and a sealing groove is provided on its flange surface, which can be directly connected to the corresponding flange surface of the external connecting pipe by bolts to form a fluid channel, and the valve seat 6 is embedded in the inner wall of the valve body flange 5, and the sealing surface of the valve seat 6 is perpendicular to the central axis of the flow channel of the valve body flange 5.

[0026] A valve stem 2 is provided on the valve control base 1. The interior of the valve seat 6 is hollow, and an annular air bag 26 is provided inside the valve seat 6. The valve seat 6 is embedded in the inner wall of the valve body flange 5, and the sealing surface of the valve seat 6 is perpendicular to the central axis of the flow channel of the valve body flange 5.

[0027] A rotary pumping part is provided on the valve stem 2, which consists of a rotating part and a pumping part. The rotating part is linked to the valve stem 2 and rotates synchronously with the rotation of the valve stem 2. The pumping part is connected to the rotating part in a transmission manner, and negative pressure is generated under the drive of the rotating part to extract and store the air inside the annular airbag 26.

[0028] The annular airbag 26 inside the valve seat 6 is used to be filled with a sealing medium. The internal air is extracted by rotating the air extraction part to achieve expansion and deformation of the airbag, thereby enhancing the sealing fit between the valve seat 6 and the valve plate 7.

[0029] In this embodiment, if Figure 3-5 As shown, the solution of this embodiment can realize the rotary air extraction part by designing the following structure: The rotating part and the exhaust part in the rotary exhaust part are composed of a crank 21, a hinge block 22, a piston rod 23, a sealing tube 24, and an air intake pipe 25. The crank 21 is arranged on the outer shaft of the valve stem 2, the hinge block 22 is arranged on the end of the crank 21 away from the valve stem 2, the piston rod 23 is arranged on the end of the hinge block 22 away from the crank 21, the sealing tube 24 is sealed on the outside of the piston rod 23, one end of the air intake pipe 25 is connected to the sealing tube 24, and the other end of the air intake pipe 25 is connected to the annular airbag 26. An electromagnetic valve is provided inside the air intake pipe 25 to control the air outlet and air intake of the air intake pipe 25. When the valve stem 2 When the valve plate 7 is driven to open, the crank 21 is synchronously driven to rotate, and then the piston rod 23 is driven to reciprocate in the sealing tube 24, and the air in the annular airbag 26 is drawn into the sealing tube 24 through the solenoid valve for storage. When the valve stem 2 is rotated into place, the solenoid valve is quickly closed to seal the gas in the sealing tube 24. When the valve plate 7 is closed, the valve stem 2 rotates in the opposite direction and drives the crank 21 and the piston rod 23 again. At this time, the solenoid valve is reopened, and the air in the sealing tube 24 is injected into the annular airbag 26 under the push of the piston rod 23, causing it to expand rapidly, thereby enhancing the sealing effect between the valve seat 6 and the valve plate 7.

[0030] In this embodiment, the groove on the valve body flange 5 is first connected to the external pipeline by bolts. When the valve plate 7 needs to be opened to convey water, the valve stem 2 is rotated forward. The valve plate 7 fixed on the valve stem 2 also rotates continuously as the valve stem 2 rotates. At the same time, the driving crank 21 is synchronously driven to rotate during the rotation of the valve stem 2. The crank 21 drives the piston rod 23 to reciprocate in the sealing tube 24 through the hinge block 22, and the air in the annular airbag 26 is drawn into the sealing tube 24 for storage through the suction pipe 25. At this time, the solenoid valve is opened, and the auxiliary gas flows quickly; when the valve stem 2 is rotated to the fully open position, the solenoid valve is quickly closed to seal the gas in the pipeline. The annular airbag 26 shrinks due to the extraction of gas, and the valve seat 6 outside it also shrinks synchronously, thereby reducing the contact resistance between the valve plate 7 and the valve seat 6.

[0031] When valve plate 7 needs to be closed, valve stem 2 rotates in the opposite direction, again driving crank 21 and piston rod 23. At this point, the solenoid valve reopens, and the air in sealing tube 24, pushed by piston rod 23, is injected into annular airbag 26 through suction pipe 25. The airbag rapidly expands, causing the valve seat 6 on its exterior to fit tightly against valve plate 7, preventing fluid leakage. Simultaneously, the rotary pumping unit also activates the packing pressure unit during operation, applying pressure to the packing, further ensuring a tight seal at the point where valve stem 2 penetrates. Example 2:

[0032] Reference Figure 3-5 and Figure 8A packing pressing part is provided on the placement seat 4, and the packing pressing part is composed of a packing piece and a pressing part. The packing piece is used to fill the sealed space in the placement seat 4, and the pressing part cooperates with the rotating part to apply pressure to the packing piece. The placement seat 4 is used to install the packing pressing part. The pressure of the packing piece is adjusted by cooperating with the pressing part and the rotating part, thereby forming a dynamic sealing protection for the valve stem 2. When the rotary exhaust part is reset, the packing pressing part is synchronously driven to reset, so that the pressure of the packing piece is restored to the initial sealing state.

[0033] In this embodiment, the scheme of this embodiment can be achieved by designing the following structure for the packing pressing portion: The packing pressing part is composed of a packing placement groove 41, a packing 42, a pressing piece 43, an annular groove 44, and a protruding rod 45. The packing placement groove 41 is opened at the axial center of the placement seat 4, and the valve stem 2 passes through the groove and is coaxially arranged with it. The packing 42 is nested in the packing placement groove 41 and tightly covers the outer periphery of the valve stem 2. The packing 42 is made of elastic silicone rubber, which has elastic properties and excellent high and low temperature performance. It is not easy to harden and crack at low temperatures. The structure of the packing 42 is designed as a double-layer lip seal. The inner layer is close to the valve stem 2 to achieve initial sealing, and the outer layer pushes the lip edge close to the groove wall through the medium pressure. When the pressing piece 43 applies pressure to the packing 42 to complete the downward pressure action, as the protruding rod 45 rotates away, the packing 42 generates a restoring force by its own elastic properties, driving the pressing piece 43 to smoothly return to its initial position.

[0034] The pressing piece 43 is arranged on the inner wall of the filler placement groove 41, and the lower surface contacts the upper surface of the filler 42. The annular groove 44 is opened on the pressing piece 43, and the depth of the annular groove 44 increases linearly along the circumferential direction. One end of the protruding rod 45 is arranged at an eccentric position on the bottom surface of the crank 21, and the other end is embedded in the annular groove 44 and slides with the groove wall. When the crank 21 rotates, the protruding rod 45 makes a circular motion along the annular groove 44, and the change in the groove depth forces the pressing piece 43 to produce an axial position.

[0035] In this embodiment, when the valve stem 2 drives the crank 21 to rotate, the protruding rod 45 fixed to the bottom surface of the crank 21 performs a circular motion accordingly. Since the protruding rod 45 is embedded in the annular groove 44 on the upper surface of the pressing plate 43, when the protruding rod 45 slides in the groove, an axial component of force will be generated due to the change in the groove depth.

[0036] During the opening process of the valve stem 2, the protruding rod 45 slides from the deepest point to the shallowest point of the annular groove 44. During this process, the pressing piece 43 is pushed by the protruding rod 45 and moves downward along the axis of the packing placement groove 41, exerting gradually increasing pressure on the annular packing. When the valve stem 2 rotates to the fully open position, the pressing force of the pressing piece 43 on the packing reaches the maximum, ensuring a tight seal at the penetration point of the valve stem 2; when the valve stem 2 rotates in the opposite direction to close the valve plate 7, the protruding rod 45 slides in the opposite direction along the annular groove 44, the pressure of the packing 42 decreases accordingly, and the top pressing piece 43 is lifted to the initial position. At the same time, the pressure block maintains the basic sealing performance and reduces the friction resistance when the valve stem 2 rotates. Example 3:

[0037] In this embodiment, a valve plate 7 is provided on the valve stem 2, and swingable spoilers are symmetrically provided on the upstream and downstream surfaces of the valve plate 7. The spoilers are continuously swung by the flow of water, thereby changing the flow direction of the fluid and disturbing the water. The spoilers are periodically swung by the force of the water flow, changing the flow direction of the fluid and forming a disturbing effect.

[0038] In this embodiment, if Figure 6-7 As shown, the spoiler can adopt the following specific structure to implement the technical solution of the embodiment: The spoiler consists of a connecting plate 71, a rotating rod 72, a torsion spring 73, and a guide plate 74. The connecting plate 71 is symmetrically arranged on the valve stem 2. The rotating rod 72 is perpendicular to the middle of the connecting plate 71. Both ends are rotatably connected to the connecting plate 71 through bearings to provide rotation for the guide plate 74. The torsion spring 73 is sleeved on the outer axis of the rotating rod 72. The torsion spring 73 is made of nickel-titanium alloy. This material not only has superelasticity and shape memory properties, but also can maintain good flexibility and fatigue resistance in an extreme low temperature environment of -200°C.

[0039] One end thereof is fixedly connected to the inner side of the connecting plate 71, and the other end is fixedly connected to the guide plate 74, providing a restoring elastic force for the guide plate 74. The guide plate 74 is arranged on the rotating rod 72, and a protective cover is provided at the connection between the rotating rod 72 and the torsion spring 73, which can resist direct impact of the fluid and reduce the surface wear of the rotating rod 72 and the risk of deformation at the connection of the torsion spring 73.

[0040] In this embodiment, when the low-temperature fluid flows through the butterfly valve, the fluid impact force acting on the front face of the guide plate 74 generates a torque around the axis of the rotating rod 72. When the torque is greater than the preload force of the torsion spring 73, the guide plate 74 overcomes the resistance of the torsion spring 73 and begins to rotate around the rotating rod 72, deflecting toward the downstream direction of the fluid, changing the original straight flow direction of the fluid, causing the fluid to produce lateral diffusion and longitudinal vortexes, forming a turbulent effect, effectively dispersing the impact force of the fluid on the valve plate 7, and reducing the risk of cavitation.

[0041] When the fluid flow rate decreases, the impact force on the guide plate 74 is relatively weakened. The elastic restoring force of the torsion spring 73 drives the guide plate 74 to rotate in the opposite direction, so that it gradually returns to its initial position. During the resetting process, the torsion spring 73 continues to provide a buffering effect to prevent the guide plate 74 from swinging violently due to inertia.

[0042] The above description is only a preferred specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any technician familiar with the technical field, within the technical scope disclosed by the present invention, who makes equivalent replacements or changes based on the technical solution and inventive concept of the present invention, should be covered by the scope of protection of the present invention.

Claims

1. A low-temperature resistant butterfly valve body, comprising a valve control base, a bracket, a placement seat, a valve body flange and a valve seat, characterized in that: The valve control base is provided with a valve stem, the interior of the valve seat is hollow, and an annular airbag is provided inside the valve seat. The valve stem is provided with a rotary air pumping portion, which is composed of a rotating member and an air pumping member. The rotating member is linked to the valve stem and rotates synchronously with the rotation of the valve stem. The air pumping portion is transmission-connected to the rotating member, and generates negative pressure under the drive of the rotating member, which is used to extract and store air inside the annular airbag; The placement seat is provided with a packing pressing portion, which is composed of a packing member and a pressing member. The packing member is used to fill the sealed space in the placement seat. The pressing member cooperates with the rotating member to apply pressure to the packing member. The valve stem is provided with a valve plate, and swingable spoilers are symmetrically provided on the upstream and downstream surfaces of the valve plate. The spoilers are continuously swung by the flow of water, thereby changing the flow direction of the fluid and disturbing the water.

2. A low temperature resistant butterfly valve body according to claim 1, characterized in that: The bracket is arranged below the valve control base and is fixed to the valve control base by bolts; The placement seat is coaxially arranged directly below the bracket, and the two are axially positioned by a guide column; The valve body flange is arranged below the placement seat, and a sealing groove is provided on the flange surface thereof, which can be directly connected to the corresponding flange surface of the external connection pipe by bolts to form a fluid channel; The valve seat is embedded in the inner wall of the valve body flange, and the valve seat sealing surface is perpendicular to the flow channel center axis of the valve body flange.

3. A low temperature resistant butterfly valve body according to claim 2, characterized in that: The placement seat is used to install the packing pressing part. Through the cooperation of the pressing part and the rotating part, the pressure of the packing is adjusted, thereby forming a dynamic sealing protection for the valve stem penetration.

4. The low temperature resistant butterfly valve body according to claim 1, characterized in that: The annular airbag inside the valve seat is used to be filled with a sealing medium. The internal air is extracted by rotating the air extraction part to achieve expansion and deformation of the airbag, thereby enhancing the sealing fit between the valve seat and the valve plate.

5. The low temperature resistant butterfly valve body according to claim 1, characterized in that: When the rotary air pumping part is reset, the packing pressing part is simultaneously driven to reset, so that the pressure of the packing piece is restored to the initial sealing state.

6. The low temperature resistant butterfly valve body according to claim 1, characterized in that: The flow-disturbing portion generates periodic swings due to the force of the water flow, thereby changing the flow direction of the fluid and forming a flow-disturbing effect.

7. A production process for a low-temperature resistant butterfly valve body, characterized in that: The following steps are involved: Material preparation: Low-temperature toughness alloy steel is used to prepare the valve control base, bracket, placement seat, valve body flange and valve seat; duplex stainless steel is used to prepare the valve plate; fluororubber, aramid fiber and stainless steel wire mesh are used to prepare the annular airbag; Component processing: CNC machining is performed on the sealing groove of the valve body flange and the valve seat mounting hole, keyways are machined at the matching parts of the valve stem and the rotating part, and CNC milling is used to machine the spiral annular groove of the packing pressure part; Component assembly: The valve seat cooled by liquid nitrogen is heat-fitted into the valve body flange, and hydraulic assembly is used to make the crank and valve stem interference fit, and the pressing piece and the packing placement groove adopt clearance fit; Overall assembly and commissioning: Install the bracket, placement seat, and valve body flange in sequence, and conduct valve plate opening and closing tests, pressure tests, and sealing performance tests at a low temperature of -196°C; Surface treatment and protection: The valve body is sprayed with low-temperature anti-corrosion coating, and the exposed part of the valve stem is plated with nickel-phosphorus alloy.

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