A globe valve applicable to low-temperature media

Abstract

The present invention discloses a globe valve applicable to low-temperature media, belonging to the technical field of valves. It is a structural improvement of the globe valve for transporting low-temperature media. Refrigerant is filled in the shock-absorbing cavity corresponding to the liquid inlet of the valve body by the valve seat and inside the valve seat to keep the pressure and temperature of the liquid inlet of the valve body relatively stable, and to avoid the deformation and generation of gaps in the sealing surfaces of the valve core and valve seat due to excessive temperature changes. After the valve is started, the valve core moves upward to maintain the normal opening degree, and the telescopic buffer structure and turbine blades arranged at the upper and lower ends of the valve core are relied on to reduce the strong pressure caused by the instantaneous hydraulic pressure on the valve core. Among them, relying on the reverse air compression effect of the telescopic air distribution sleeve rod, the turbine blade moves downward. When the opening degree of the valve core is the largest, the turbine blade is close to the valve seat, and the turbine blade is driven by the low-temperature medium to rotate, thereby consuming part of the kinetic energy in the medium, and reducing the impact force of the high-speed fluid medium on the valve core and the outlet pipe fitting by passive flow limiting.

Description

Technical Field

[0001] The present invention relates to the technical field of valves, and more specifically, to a globe valve applicable to low-temperature media. Background Art

[0002] With the development of science and technology, more and more industrial fields are applying low-temperature media such as liquid hydrogen, liquid oxygen, and liquid nitrogen. The low-temperature globe valve is applied to storage and transportation equipment for low-temperature media, such as cryogenic pressure vessels like storage tanks, tank trucks, and tank containers, and is used to control the opening and closing operations of the pipelines of cryogenic pressure vessels.

[0003] After retrieval, in the invention patent with the patent publication number CN116292931A, a liquid hydrogen low-temperature globe valve is introduced. By providing a valve body extension pipe on the outer wall of the valve stem and arranging a guiding heat insulation ring between the valve stem and the valve body extension pipe, the heat convection of the liquid hydrogen medium in the valve is reduced, so that the sealed corrugated pipe fittings and other sealing components are within the safe operating temperature range.

[0004] However, in the actual application of this invention, relying on increasing the length of the valve stem and adding heat insulation materials outside the valve stem can reduce heat transfer to a certain extent. However, under low-temperature working conditions, the thermal expansion and contraction effect of the medium is more obvious, which easily causes deformation or damage to the sealing surfaces of the sealing structures such as the valve core, affecting its sealing effect. In addition, when the low-temperature medium flows through the valve, pressure fluctuations may occur for various reasons. A large hydraulic difference will directly increase the working burden of the internal sealing structure of the valve body, easily leading to a significant reduction in the sealing performance of the valve core and the valve stem relative to the valve body.

[0005] Therefore, we propose a globe valve applicable to low-temperature media for the existing problems. Summary of the Invention

[0006] The purpose of the present invention is to solve the problem that the existing globe valve is more likely to affect the sealing performance of its sealing structure under low-temperature working conditions, and to provide a globe valve applicable to low-temperature media compared with the existing technology.

[0007] The purpose of the present invention can be achieved by the following technical solutions: A globe valve applicable to low-temperature media includes a valve body, a valve cover, and a valve stem. A valve core extending into the valve body is provided at the bottom end of the valve stem. A valve seat adapted to the valve core is provided inside the valve body. The internal space of the valve seat corresponding to the liquid inlet of the valve body is set as a shock-absorbing cavity, and the inner wall of the shock-absorbing cavity and the inside of the valve seat are filled with a refrigerant.

[0008] A sealing cover coaxial with the upper end of the valve core is fixedly connected to the upper end of the valve core. A sealing ring groove corresponding to the position of the sealing cover is formed at the bottom end of the valve cover. A movable piece is movably connected to the bottom end of the valve core. A turbine blade is rotatably installed at the bottom end of the movable piece. A buffer cavity is formed at the bottom end of the valve cover inside the sealing ring groove. Telescopic air-distributing sleeve rods symmetrically distributed on both sides of the valve rod and connected to the upper end of the valve core at the lower end are fixed on both sides of the buffer cavity. A push rod is movably sleeved in the telescopic end of the telescopic air-distributing sleeve rod. The bottom end of the push rod penetrates through the valve core and is connected to the upper end of the movable piece.

[0009] Further, the height of the sealing ring groove is greater than the height of the sealing cover, and a first buffer spring located at the top end of the sealing cover is sleeved inside the sealing ring groove.

[0010] Further, the valve core includes an upper disc sealing portion and a lower conical sealing portion. A conical sealing groove adapted to the lower conical sealing portion is formed inside the valve seat.

[0011] Further, an inner groove is formed inside the upper disc sealing portion. An outer convex ring adjacent to the inner groove and protruding downward is provided on the outer side of the upper disc sealing portion. The cross-section of the outer edge of the outer convex ring and the inner edge of the inner groove forms an S-shaped structure. Inner convex rings and outer grooves adapted to the inner groove and the outer convex ring are respectively provided on the inner and outer sides of the valve seat.

[0012] Further, the movable piece is a frustum-shaped structure connected to the bottom end of the lower conical sealing portion, and the outer diameter length of the turbine blade is smaller than the outer diameter length of the lowest outlet of the conical sealing groove.

[0013] Further, the telescopic air-distributing sleeve rod includes an upper rod body fixed to the bottom of the buffer cavity. An air cavity is formed inside the upper rod body. A lower rod body is slidably installed in the air cavity. The telescopic end of the lower rod body extends downward and is fixed to the upper end wall of the valve core. A second buffer spring connected between the buffer cavity and the valve core is sleeved outside the upper rod body and the lower rod body.

[0014] Further, a material-pushing cavity for the up-and-down movement of the push rod is formed at the lower end of the lower rod body. A suction hole communicating with the material-pushing cavity and the air cavity is formed at the upper end of the lower rod body. The air cavity is filled with gas.

[0015] Further, the inner hole diameter of the suction hole is smaller than the inner hole diameter of the material-pushing cavity, and the length of the suction hole is greater than the length of the material-pushing cavity.

[0016] Further, an upward-extending long-necked sleeve is provided at the upper end of the valve cover. An inner heat-insulating sleeve and an outer heat-insulating sleeve covering the outside of the valve rod are embedded and installed inside the long-necked sleeve. The outer heat-insulating sleeve is located above the inner heat-insulating sleeve and extends outside the long-necked sleeve.

[0017] Compared with the prior art, the advantages of the present invention are as follows:

[0018] (1) This scheme is to improve the structure of the stop valve for conveying low-temperature media. The internal space of the valve seat corresponding to the valve body liquid inlet is set as a shock-absorbing chamber. The inner wall of the shock-absorbing chamber and the inside of the valve seat are filled with refrigerant to keep the pressure and temperature of the valve body liquid inlet relatively stable, avoiding the deformation of the valve core and the valve seat sealing surface due to excessive temperature changes and the generation of gaps. After the valve is started, the valve core moves upward to maintain the normal opening, relying on the telescopic buffer structure and turbine blades set at the upper and lower ends of the valve core to reduce the strong pressure on the valve core caused by the instantaneous hydraulic pressure;

[0019] The process of limiting the flow of turbine blades is specifically manifested as follows: when the valve core drives the telescopic air sleeve rod to contract upward, the turbine blades move downward by relying on the reverse air compression effect of the telescopic air sleeve rod. When the valve core is opened to the maximum, the turbine blades are close to the valve seat. When the low-temperature medium flows through the turbine blades at high speed, the turbine blades are driven to rotate, thereby consuming part of the kinetic energy in the fluid medium to reduce the impact force of the high-speed fluid medium on the valve core and the outlet pipe fittings.

[0020] (2) Compared with the traditional simple sealing surface structure, this scheme also optimizes and improves the structure of the valve core and the valve seat interface. The interface between the lower conical sealing part and the conical sealing groove of the valve seat is used as the main sealing surface, and the annular curved surface formed by the upper disc sealing part and the upper surface of the valve seat is used as the auxiliary sealing surface to improve the sealing performance of the valve core and the valve seat after docking. In addition, an upper sealing cover adapted to the sealing ring groove is added to the upper end of the valve core. When the valve core is in the closed state, the upper end of the upper sealing cover is sealed in the sealing ring groove to form an additional sealing surface in the flow space of the valve inlet and outlet, thereby further improving the sealing effect. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 It is a schematic diagram of the external structure of the present invention;

[0022] Figure 2 is a cross-sectional view inside the valve body of the present invention;

[0023] Figure 3 It is an overall cross-sectional view of the present invention;

[0024] Figure 4 is an internal cross-sectional view of the present invention;

[0025] Figure 5 It is a structural schematic diagram of the valve cover, valve core and valve seat of the present invention when they are detached;

[0026] Figure 6 A top view of the valve core and valve seat of the present invention when they are separated;

[0027] Figure 7 It is a cross-sectional view of the junction between the valve core and the telescopic air sleeve rod of the present invention;

[0028] Figure 8 This is a cross-sectional view of the combination of the valve core and the telescopic air distribution sleeve rod after the valve core of the present invention is lifted upward.

[0029] Figure 9 This is a schematic diagram of the fluid flow direction when the valve core opening of the present invention is at its maximum.

[0030] Description of the reference numerals in the figure:

[0031] 1. Valve body; 2. Valve cover; 201. Sealing ring groove; 3. Valve stem; 4. Valve core; 401. Inner groove; 402. Outer convex ring; 5. Valve seat; 501. Inner convex ring; 502. Outer groove; 6. Movable piece; 7. Turbine blade; 8. Upper sealing cover; 9. Telescopic air distribution sleeve rod; 91. Upper rod body; 911. Air cavity; 92. Lower rod body; 921. Suction hole; 922. Pushing cavity; 93. Second buffer spring; 10. Push rod; 11. First buffer spring; 12. Long-necked sleeve; 13. Inner heat insulation sleeve; 14. Outer heat insulation sleeve. Specific implementation manner

[0032] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

[0033] Embodiment 1: Under low-temperature working conditions, the thermal expansion and contraction effect of the medium is more obvious, which easily causes the sealing surface of the sealing structure such as the valve core to deform or be damaged, affecting its sealing effect. When the low-temperature medium flows through the valve at high speed, pressure fluctuations may occur for various reasons. A large hydraulic difference will directly increase the working burden of the internal sealing structure of the valve body. For this, the following technical solutions are proposed:

[0034] This embodiment discloses a globe valve applicable to low-temperature media. Please refer to Figures 1-4 , which includes a valve body 1, a valve cover 2 and a valve stem 3. A handwheel is provided at the top of the valve stem 3, and the handwheel is used as the driving structure for the up and down movement of the valve stem 3. The bottom end of the valve stem 3 is provided with a valve core 4 extending into the interior of the valve body 1. An inner space of the valve body 1 corresponding to the liquid inlet of the valve body 1 is provided as a shock-absorbing cavity, and the inner wall of the shock-absorbing cavity and the interior of the valve seat 5 are filled with refrigerant.

[0035] A cavity is opened in the shock-absorbing cavity and the inner wall of the valve seat 5, and an appropriate amount of refrigerant is filled in the cavity. The filling of the refrigerant does not affect the overall hardness requirement of the valve. Filling the refrigerant can keep the pressure and temperature at the shock-absorbing cavity and the valve seat 5 relatively stable, avoiding the deformation of the valve sealing structure caused by temperature changes. In addition, the refrigerant filled at the valve inlet can play a buffering role, absorbing and dissipating part of the pressure fluctuation, making the pressure before and after the valve more stable, reducing the impact on the internal structure of the valve and the pipeline system, and improving the stability of the entire system.

[0036] The upper end of the valve cover 2 is provided with an upward-extending long-necked sleeve 12. An inner heat-insulating sleeve 13 and an outer heat-insulating sleeve 14 covering the outside of the valve stem 3 are embedded and installed inside the long-necked sleeve 12. The outer heat-insulating sleeve 14 is located above the inner heat-insulating sleeve 13 and extends outside the long-necked sleeve 12. The long-necked valve cover structure is adopted, and together with the inner heat-insulating sleeve 13 and the outer heat-insulating sleeve 14, a low-temperature isolation cavity is formed, which can reduce the heat transfer from the outside.

[0037] Please refer to Figures 2-5 , the upper end of the valve core 4 is fixedly connected with an upper sealing cover 8 arranged coaxially therewith. A sealing ring groove 201 corresponding to the position of the upper sealing cover 8 is opened at the bottom end of the valve cover 2. The height of the sealing ring groove 201 is greater than the height of the upper sealing cover 8. A first buffer spring 11 located at the top end of the upper sealing cover 8 is sleeved inside the sealing ring groove 201. The upper space on the side of the valve seat 5 corresponding to the liquid outlet of the valve body 1 can be used as a flow-through space for the fluid to flow inside and outside. The upper sealing cover 8 is placed in the flow-through space in the closed state of the valve, and the fluid is discharged through the open valve seat 5, the flow-through space, and the liquid outlet of the valve body 1.

[0038] Please refer to Figures 4-7 , the valve core 4 includes an upper disc sealing part and a lower conical sealing part. A conical sealing groove adapted to the lower conical sealing part is opened inside the valve seat 5. An inner groove 401 is opened on the inner side of the upper disc sealing part. An outer convex ring 402 adjacent to the inner groove 401 and protruding downward is provided on the outer side of the upper disc sealing part. The cross-section of the outer edge of the outer convex ring 402 and the inner edge of the inner groove 401 forms an S-shaped structure. Inner convex rings 501 and outer grooves 502 adapted to the inner groove 401 and the outer convex ring 402 are respectively provided on the inner and outer sides of the valve seat 5;

[0039] Compared with the traditional simple sealing surface structure, the docking surface structure of the valve core 4 and the valve seat 5 is optimized and improved;

[0040] In the closed state of the valve, using the handwheel as the driving component for the up and down movement of the valve stem 3, the valve stem 3 drives the valve core 4 to move downward until the valve core 4 is hermetically docked with the valve seat 5. The docking surface between the lower conical sealing part and the conical sealing groove of the valve seat 5 is used as the main sealing surface, and the annular curved surface formed by the upper disc sealing part and the upper surface of the valve seat 5 is used as the auxiliary sealing surface, forming a double sealing surface to improve the sealing performance after the docking of the valve core 4 and the valve seat 5;

[0041] It should be added here that the conical sealing surfaces where the lower conical sealing part and the valve seat 5 are butted are made of materials with good low-temperature performance and wear resistance, such as cobalt-based hard alloys, etc., which are surfacing welded on the sealing surfaces. The outer end faces of the inner convex ring 501 and the outer convex ring 402 are coated with soft materials such as rubber and polytetrafluoroethylene, so as to improve the sealing effect of the valve core 4 under low-temperature working conditions in the form of soft and hard combined sealing.

[0042] When the valve core 4 is in the closed state, the upper end of the upper sealing cover 8 is sealed in the sealing ring groove 201, so as to form an additional sealing surface in the flow space at the inlet and outlet of the valve, further improving the sealing effect.

[0043] When the valve is in the open state, drive the handwheel, the valve stem 3 moves upward, the valve core 4 gradually disengages from the valve seat 5 until the upper end wall of the valve core 4 contacts the lower end wall of the valve cover 2. During this process, the upper sealing cover 8 moves upward synchronously into the sealing ring groove 201, compresses the first buffer spring 11, and the compression deformation of the first buffer spring 11 plays a buffering role in the upward movement of the valve core 4, and conducts the flow space between the inlet and outlet of the valve.

[0044] Embodiment 2: On the basis of Embodiment 1, a buffer and flow-limiting structure is added to the upper and lower ends of the valve core 4 to improve the impact resistance of the valve core 4 after opening to cope with high-speed fluid media, specifically as follows:

[0045] Please refer to Figures 4-7 , a movable piece 6 is movably connected to the bottom end of the valve core 4, a turbine blade 7 is rotatably installed at the bottom end of the movable piece 6, the movable piece 6 is a frustum-shaped structure connected to the bottom end of the lower conical sealing part, and the outer diameter length of the turbine blade 7 is less than the outer diameter length of the lowest outlet of the conical sealing groove.

[0046] A buffer cavity is opened at the bottom end of the valve cover 2 inside the sealing ring groove 201. Symmetrically distributed on both sides of the buffer cavity and fixed to the left and right sides of the valve stem 3 and the lower ends are connected to the upper end of the valve core 4 are telescopic air-distributing sleeve rods 9. A push rod 10 is movably sleeved inside the telescopic end of the telescopic air-distributing sleeve rod 9, and the bottom end of the push rod 10 penetrates through the valve core 4 and is connected to the upper end of the movable piece 6.

[0047] Specifically, please refer to Figures 7-9 , the telescopic air-distributing sleeve rod 9 includes an upper rod body 91 fixed to the bottom of the buffer cavity. An air cavity 911 is opened in the upper rod body 91. A lower rod body 92 is slidably installed in the air cavity 911. The telescopic end of the lower rod body 92 extends downward and is fixed to the upper end wall of the valve core 4. A second buffer spring 93 is sleeved outside the upper rod body 91 and the lower rod body 92 and is connected between the buffer cavity and the upper end wall of the valve core 4. A push cavity 922 for the up and down movement of the push rod 10 is opened at the lower end of the lower rod body 92, and a suction hole 921 communicating with the push cavity 922 and the air cavity 911 is opened at the upper end of the lower rod body 92;

[0048] The inside of the air cavity 911 is filled with gas, and the gas can flow through the air cavity 911, the suction hole 921, and the material pushing cavity 922. The inner diameter of the suction hole 921 is smaller than the inner diameter of the material pushing cavity 922, and the length of the suction hole 921 is greater than the length of the material pushing cavity 922. The internal volumes of the suction hole 921 and the material pushing cavity 922 are smaller than the internal volume of the air cavity 911. Therefore, when the lower rod body 92 is completely pushed into the air cavity 911, the gas inside the air cavity 911 is squeezed into the suction hole 921 and the material pushing cavity 922, and the gas in the suction hole 921 and the material pushing cavity 922 is in a compressed state, thus exerting a squeezing force on the push rod 10 to push it downward.

[0049] The solution during the valve opening process is as follows: The valve core 4 moves upward with the valve rod 3 and gradually disengages from the valve seat 5. At this time, the lower rod body 92 is pushed into the air cavity 911 of the upper rod body 91, gradually compressing the gas in the air cavity 911. After the gas in the air cavity 911 is compressed, it is reversely squeezed into the material pushing cavity 922 through the suction hole 921. Therefore, during the upward movement of the valve core 4, the gas is compressed and squeezed into the material pushing cavity 922, causing the push rod 10 to drive the movable piece 6 and the turbine blade 7 to move downward;

[0050] It should be further noted that this process is an action of gradually opening the flow space, and the fluid medium continuously flows out through the flow space of the valve body 1. Therefore, the pressures borne by the turbine blade 7 and the movable piece 6 gradually decrease. The movable piece 6 and the turbine blade 7 below it can smoothly move downward under the action of the reverse air pressure. The valve core 4 gradually opens upward, and the turbine blade 7 moves upward with the valve core 4 in the flow space. When the low-temperature fluid medium flows through the turbine blade 7 at a high speed, it drives the turbine blade 7 to rotate, thereby consuming part of the kinetic energy in the fluid medium. Until the valve core 4 reaches the maximum opening, the turbine blade 7 moves downward under the action of the reverse air pressure and just acts on the flow space near the valve seat 5. The continuously flowing fluid medium fully acts on the turbine blade 7, and the rotating turbine blade 7 continuously consumes the kinetic energy of the fluid medium to reduce the impact force of the high-speed fluid medium on the valve core 4 and the outlet pipe fitting.

[0051] The solution during the valve closing process is as follows; The valve rod 3 pushes the valve core 4 downward, gradually narrowing the flow space until the valve core 4 is hermetically docked with the valve seat 5;

[0052] During this process, on the one hand, relying on the buffering effects of the buffer spring 11 and the telescopic air distribution sleeve rod 9, compared with only acting the valve core 4 on the valve rod 3, the stability of the downward movement of the valve core 4 is improved, and the rotating turbine blade 7 continuously reduces the impact of the fluid medium on the valve core 4 until the valve core 4 is completely hermetically docked with the valve seat 5;

[0053] On the other hand, as the flow space gradually shrinks, it becomes increasingly difficult for the fluid medium to be discharged. As a result, the turbine blade 7 and the movable piece 6 will bear greater upward pressure. The movable piece 6 squeezes a pair of push rods 10 to reset upward again into the material pushing cavity 922, and along with the downward sliding of the lower rod body 92 inside the upper rod body 91, a negative pressure state is formed inside the air cavity 911. The compressed gas in the material pushing cavity 922 is replenished into the air cavity 911 again, which not only facilitates the reset between the movable piece 6 and the valve core 4 but also restores the gas distribution inside the telescopic air distribution sleeve rod 9, making the inside of the telescopic air distribution sleeve rod 9 in a stable state to prepare for the next valve opening.

[0054] In summary, for the structural improvement of the globe valve applicable to low-temperature medium working conditions, the internal space of the valve seat 5 corresponding to the liquid inlet of the valve body 1 is set as a shock absorption cavity, and a refrigerant is filled on the inner wall of the shock absorption cavity and inside the valve seat 5 to keep the pressure and temperature of the internal space near the liquid inlet of the valve body 1 relatively stable, avoiding the generation of gaps due to the deformation of the sealing surfaces of the valve core 4 and the valve seat 5 caused by temperature changes;

[0055] Secondly, a buffer structure composed of a turbine blade 7 movably installed at the bottom end of the valve core 4, an upper sealing cover 8, a first buffer spring, and a pair of telescopic air distribution sleeve rods 9 is added at the upper end of the valve core 4. After the valve is started, the valve core 4 moves upward along with the valve stem 3. On the one hand, on the basis of maintaining the normal opening degree of the valve core 4, the strong pressure caused by the instantaneous hydraulic pressure on the valve core 4 is reduced. On the other hand, relying on the reverse air pressure action of the telescopic air distribution sleeve rods 9, the turbine blade 7 moves downward to act on the flow space of the inlet and outlet. When the low-temperature medium flows through the turbine blade 7 at high speed, it drives the turbine blade 7 to rotate, thereby consuming part of the kinetic energy in the medium to reduce the impact force of the high-speed medium on the valve core 4 and the outlet pipe fittings.

[0056] The above is only a preferred specific embodiment of the present invention; however, the protection scope of the present invention is not limited thereto; any person skilled in the art within the technical scope disclosed by the present invention, according to the technical solution of the present invention and its improved concept, makes equivalent substitutions or changes, and all should be covered within the protection scope of the present invention.

Claims

1. A stop valve suitable for low-temperature media, comprising a valve body (1), a valve cover (2) and a valve stem (3), wherein the bottom end of the valve stem (3) is provided with a valve core (4) extending into the interior of the valve body (1), and the interior of the valve body (1) is provided with a valve seat (5) adapted to the valve core (4), characterized in that: The internal space of the valve seat (5) corresponding to the liquid inlet of the valve body (1) is configured as a damping cavity, and the damping cavity and the interior of the valve seat (5) are both filled with refrigerant; The upper end of the valve core (4) is fixedly connected to an upper sealing cover (8) arranged coaxially therewith, the bottom end of the valve cover (2) is provided with a sealing ring groove (201) corresponding to the position of the upper sealing cover (8), the bottom end of the valve core (4) is movably connected to a movable plate (6), the bottom end of the movable plate (6) is rotatably mounted with a turbine blade (7), the bottom end of the valve cover (2) is provided with a buffer cavity located inside the sealing ring groove (201), both sides of the buffer cavity are fixed with telescopic air-distributing sleeve rods (9) symmetrically distributed on the left and right sides of the valve stem (3) and the lower end of which is connected to the upper end of the valve core (4), the telescopic end of the telescopic air-distributing sleeve rod (9) is movably sleeved with a push rod (10), the bottom end of the push rod (10) passes through the valve core (4) and is connected to the upper end of the movable plate (6); The telescopic air sleeve rod (9) comprises an upper rod body (91) fixed to the bottom of the buffer cavity, an air cavity (911) is provided in the upper rod body (91), a lower rod body (92) is slidably mounted in the air cavity (911), a telescopic end of the lower rod body (92) extends downward and is fixed to the upper end wall of the valve core (4), and a buffer spring (93) connected between the buffer cavity and the valve core (4) is sleeved on the outer sides of the upper rod body (91) and the lower rod body (92), and the lower rod body (92) is sleeved with a buffer spring (93) connected between the buffer cavity and the valve core (4). A pushing cavity (922) for the push rod (10) to move up and down is provided at the lower end of the lower rod body (92), and a suction hole (921) connected to the pushing cavity (922) and the air cavity (911) is provided at the upper end of the lower rod body (92), and the air cavity (911) is filled with gas, the inner diameter of the suction hole (921) is smaller than the inner diameter of the pushing cavity (922), and the length of the suction hole (921) is greater than the length of the pushing cavity (922).

2. A stop valve suitable for low temperature media according to claim 1, characterized in that: The height of the sealing ring groove (201) is greater than the height of the upper sealing cover (8), and a buffer spring 1 (11) located at the top of the upper sealing cover (8) is sleeved inside the sealing ring groove (201).

3. A stop valve suitable for low temperature media according to claim 1, characterized in that: The valve core (4) comprises an upper disc sealing portion and a lower conical sealing portion, and a conical sealing groove matching the lower conical sealing portion is provided inside the valve seat (5).

4. A stop valve suitable for low temperature media according to claim 3, characterized in that: An inner groove (401) is provided on the inner side of the upper disc sealing portion, and an outer convex ring (402) is provided on the outer side of the upper disc sealing portion, which is adjacent to the inner groove (401) and protrudes downward. The cross-section of the outer edge of the outer convex ring (402) and the inner edge of the inner groove (401) form an S-shaped structure. The inner and outer sides of the valve seat (5) are respectively provided with an inner convex ring (501) and an outer groove (502) that are compatible with the inner groove (401) and the outer convex ring (402).

5. A stop valve suitable for low temperature medium according to claim 4, characterized in that: The movable sheet (6) is a truncated cone-shaped structure connected to the bottom end of the lower conical sealing portion, and the outer diameter length of the turbine blade (7) is smaller than the outer diameter length of the outlet at the bottom end of the conical sealing groove.

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