An underwater failure shut-off valve

Abstract

This invention discloses an underwater fail-safe shut-off valve, relating to the field of marine exploration and drilling equipment technology. It includes a actuator assembly and a preparation valve assembly. The actuator assembly includes a piston assembly that divides the interior of the actuator assembly into independent drive chambers and balance chambers, which are hydraulically connected externally. The piston assembly is driven to one end of the valve stem. A force-applying component is disposed between the piston assembly and the inner wall end face of the actuator assembly. The preparation valve assembly includes an actuator that controls the opening and closing of the valve via the piston-driven actuator. After a hydraulic system failure, the piston assembly is no longer compressed by hydraulic oil. Under the elastic drive of the force-applying component, the piston assembly pushes the hydraulic oil in the drive chamber into the balance chamber and drives the valve stem, causing the preparation valve assembly to close, thereby achieving fail-safe shut-off of the underwater shut-off valve.

Description

Technical Field

[0001] This invention relates to the field of marine exploration drilling equipment technology, and in particular to an underwater failure shut-off valve. Background Technology

[0002] Subsea shut-off valves are core safety equipment in subsea oil and gas production systems. Their primary function is to quickly cut off the flow of oil and gas in emergency situations, thereby effectively preventing leakage risks and the escalation of accidents.

[0003] When working in underwater environments, there are generally two operating methods: operation by an unmanned underwater vehicle (UUV) or operation by a diver. Especially in deep water environments, operations can only be completed by an unmanned underwater vehicle.

[0004] However, because underwater shut-off valves operate in the deep-sea environment for extended periods, the actuators controlling their opening and closing are highly susceptible to failure, leading to valve malfunctions. Therefore, there is an urgent need for an underwater fail-safe shut-off valve that can automatically close after actuator failure. Summary of the Invention

[0005] To solve the above technical problems, the present invention provides an underwater failure shut-off valve that can automatically close after the hydraulic system fails.

[0006] To achieve the above objectives, the present invention provides the following solution: This invention provides an underwater failure shut-off valve, comprising: A drive assembly includes a piston assembly that divides the interior of the drive assembly into an independent drive chamber and a balance chamber. A first hydraulic port is located at the end of the drive chamber away from the balance chamber, and a second hydraulic port is located at the end of the balance chamber away from the drive chamber. The first and second hydraulic ports are hydraulically connected externally to the drive assembly. The piston assembly is drively connected to one end of a valve stem. A force-applying component is located between the piston assembly and the inner wall end face of the drive assembly. This force-applying component can apply a force along the axial direction of the valve stem to the piston assembly, with the direction of the force pointing from the balance chamber to the drive chamber. A preparation valve assembly includes a valve body, in which an actuator is disposed. Along the axial direction of the valve stem, the actuator has a first position and a second position. When the actuator is in the first position, the preparation valve assembly is in a closed state. When the actuator is in the second position, the preparation valve assembly is in an open state. The actuator is connected to one end of the valve stem.

[0007] Optionally, the actuator assembly includes an actuator body, which is connected to the valve body via a valve cover. A hydraulic cylinder is provided at one end of the actuator body away from the valve cover. The piston assembly is slidably disposed within the hydraulic cylinder. The force-applying component is disposed between the piston assembly and the valve cover.

[0008] Optionally, a packing gland is provided between the valve stem and the valve cover, and at least two sealing rings are provided between the packing gland and the valve cover. A relief valve is provided on the valve cover, and the two sealing rings are connected to the relief valve through a pressure relief channel.

[0009] Optionally, the force-applying component includes a first elastic element and a second elastic element, which are coaxially arranged with the valve stem.

[0010] Optionally, a spring pressure plate is further provided between the piston assembly and the force application assembly, the diameter of the spring pressure plate being larger than the inner diameter of the drive cavity; at least one through hole is provided on the spring pressure plate along the axial direction of the valve stem.

[0011] Optionally, a valve stem connector is provided between the spring pressure plate and the valve stem. One end of the valve stem connector is threaded to the valve stem, and the other end passes through the spring pressure plate and is connected to the lock nut.

[0012] Optionally, both the first elastic element and the second elastic element are helical springs, and the first elastic element and the second elastic element have opposite directions of rotation.

[0013] Optionally, the actuator is provided with a flow channel. When the actuator is in the first position, the flow channel is disconnected from the inlet and outlet ends of the valve body, and the preparation valve assembly is in a closed state. When the actuator is in the second position, the flow channel is connected to the inlet and outlet ends of the valve body, and the preparation valve assembly is in an open state.

[0014] Optionally, the end of the piston assembly furthest from the valve stem is connected to the over-control rod, which is located within the over-control interface.

[0015] Optionally, an indicator hole is provided on one side of the supercontrol interface along the axial direction of the supercontrol rod, the supercontrol rod is connected to one end of the indicator rod, and the other end of the indicator rod passes through the indicator hole.

[0016] The present invention achieves the following technical effects compared to the prior art: When using the underwater fail-safe shut-off valve provided by this invention, hydraulic oil is introduced into the drive chamber through the first hydraulic interface, causing the piston assembly to move towards the balance chamber against the force application component. During the movement of the piston assembly, the valve stem drives the actuator to move within the valve body, causing the actuator to switch from the first position to the second position and remain there. At this time, the preparation valve assembly is in the open state. After the hydraulic system fails, due to the hydraulic connection between the first and second hydraulic interfaces, the piston assembly is no longer squeezed by the hydraulic oil. Under the elastic drive of the force application component, the piston assembly pushes the hydraulic oil in the drive chamber to flow out from the first hydraulic interface and into the balance chamber from the second hydraulic interface, and drives the valve stem. The valve stem drives the actuator to switch from the second position to the first position, causing the preparation valve assembly to be in the closed state, thereby realizing the fail-safe shut-off of the underwater shut-off valve. Attached Figure Description

[0017] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0018] Figure 1 This is a cross-sectional view of the subsea tree valve in the open state in a preferred embodiment of the present invention; Figure 2 This is a cross-sectional view of the subsea tree valve actuator assembly in a preferred embodiment of the present invention; Figure 3 This is a cross-sectional view of the valve assembly for preparing the subsea tree valve in a preferred embodiment of the present invention; In the diagram: A-Actuator assembly, B-Preparation valve assembly, 1-Override interface, 2-Override lever, 3-Glander cap, 4-Indicator rod, 5-Upper packing gland, 6-Lower packing gland, 7-Piston pressure plate, 8-Piston, 9-Piston joint, 10-Hydraulic cylinder, 11-Locking nut, 12-Spring pressure plate, 13-Valve stem joint, 14-Outer ring spring, 15-Inner ring spring, 16-Actuator body, 17-Packing gland, 18-Relief valve, 19-Rod seal, 20-Valve cover, 21-Valve stem, 22-Valve body, 23-Valve seat, 24-Valve plate, 25-Metal washer ring. Detailed Implementation

[0019] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0020] Example 1: like Figures 1 to 3 As shown, this embodiment provides an underwater failure shut-off valve, including: The actuator assembly A includes a piston assembly that divides the interior of the actuator assembly A into an independent drive chamber and a balance chamber. A first hydraulic interface is provided at the end of the drive chamber away from the balance chamber, and a second hydraulic interface is provided at the end of the balance chamber away from the drive chamber. The first hydraulic interface and the second hydraulic interface are hydraulically connected externally to the actuator assembly A. The piston assembly is drivenly connected to one end of the valve stem 21. A force-applying component is provided between the piston assembly and the inner wall end face of the actuator assembly A. The force-applying component can apply power to the piston assembly in the axial direction of the valve stem, and the direction of the power is from the balance chamber to the drive chamber. The preparation valve assembly B includes a valve body 22, and an actuator is provided inside the valve body 22. Along the axial direction of the valve stem 21, the actuator has a first position and a second position. When the actuator is in the first position, the preparation valve assembly B is in a closed state. When the actuator is in the second position, the preparation valve assembly B is in an open state. The actuator is connected to one end of the valve stem 21.

[0021] When using the underwater fail-safe shut-off valve in this embodiment, hydraulic oil is introduced into the drive chamber through the first hydraulic interface, causing the piston assembly to move towards the balance chamber against the force application component. During the movement of the piston assembly, the valve stem 21 drives the actuator to move within the valve body 22, causing the actuator to switch from the first position to the second position and remain there. At this time, the preparation valve assembly B is in the open state. After the hydraulic system fails, since the first hydraulic interface and the second hydraulic interface are hydraulically connected, the piston assembly is no longer squeezed by the hydraulic oil. Under the elastic drive of the force application component, the piston assembly pushes the hydraulic oil in the drive chamber to flow out from the first hydraulic interface and into the balance chamber from the second hydraulic interface, and drives the valve stem 21. The valve stem 21 drives the actuator to switch from the second position to the first position, causing the preparation valve assembly B to be in the closed state, thereby realizing the fail-safe shut-off of the underwater shut-off valve.

[0022] The hydraulic system specifically includes a hydraulic pump, a normally open solenoid valve, and a control module. Both the hydraulic pump and the normally open solenoid valve are electrically connected to the control module. The hydraulic pump and the solenoid valve are sequentially located in the hydraulic pipeline between the first and second hydraulic interfaces. The normally open solenoid valve remains open when power is off. When the preparatory valve assembly B needs to be opened, the control module sends a signal to the hydraulic pump, which starts running and pumps hydraulic oil from the balance chamber into the drive chamber until the actuator reaches the second position. At this point, the preparatory valve assembly B opens, and the control module energizes the normally open solenoid valve to close it. At this time, the hydraulic oil in the drive chamber... The hydraulic oil maintains pressure, keeping the preparation valve assembly B open. In the event of a hydraulic system failure, the normally open solenoid valve de-energizes and opens, creating a passage in the hydraulic pipeline between the first and second hydraulic interfaces. When the force-applying component applies force to the piston assembly, the piston assembly moves into the drive chamber, causing the hydraulic oil in the drive chamber to flow along the hydraulic pipeline where the normally open solenoid valve is located to the balance chamber. During this process, the piston assembly drives the valve stem 21, which in turn drives the actuator to switch from the second position to the first position, keeping the preparation valve assembly B closed, thus achieving the failure shut-off of the underwater shut-off valve.

[0023] The drive assembly A includes a drive body 16, which is connected to the valve body 22 via a valve cover 20. A hydraulic cylinder 10 is provided at the end of the drive body 16 away from the valve cover 20. A piston assembly is slidably disposed within the hydraulic cylinder 10. A force-applying assembly is disposed between the piston assembly and the valve cover 20.

[0024] The drive body 16 has two ports on its upper and lower parts for flushing the internal cavity of the drive body 16.

[0025] A packing gland 17 is installed between the valve stem 21 and the valve cover 20. The inner diameter of the packing gland 17 has two shaft seals and a wear ring, while the outer diameter has an O-ring and a lip seal. These seals, along with the O-ring and lip seal, are used to seal the pressure within the balance chamber, preventing hydraulic oil leakage from the inner and outer diameter surfaces of the packing gland 17. The wear ring prevents friction between the valve stem 21 and the packing gland 17, reducing wear. Below the packing gland 17 is a rod seal 19, employing a multi-layer sealing structure to seal the pressure of the medium from the valve body 22. A gasket is installed above the packing gland 17 to adjust the valve's flow diameter. The packing gland 17 is detachably connected to the valve cover 20 by screws, which also limit the movement of the lower rod seal 19, ensuring the valve's sealing performance. The bottom of the valve cover 20 has an inverted triangular limiting position that engages with the inclined surface of the valve stem 21. This limits the valve stem 21 when the valve is closed, allowing it to withstand the elastic force of the force-applying components. A lip seal and an O-ring are provided between the packing gland 17 and the valve cover 20. A relief valve 18 is installed on the valve cover 20, and the lip seal and O-ring are connected to the relief valve 18 through a pressure relief channel. When the pressure in the balance chamber is too high, the hydraulic oil squeezes the O-ring, causing it to deform and the seal to fail. The hydraulic oil is then discharged through the pressure relief channel and the relief valve 18, reducing the pressure inside the balance chamber and preventing damage to the valve components.

[0026] The valve cover 20 and the valve body 22 are sealed by a metal gasket 25 and an O-ring.

[0027] The force-applying assembly includes a first elastic element and a second elastic element, which are coaxially arranged with the valve stem 21. Both the first and second elastic elements are helical springs, namely an outer coil spring 14 and an inner coil spring 15, with opposite directions of rotation. During the compression or reset process of the outer coil spring 14 and the inner coil spring 15, the oppositely rotating outer coil spring 14 and the inner coil spring 15 can cancel each other out torsional forces and provide sufficient force to the piston assembly, reducing sudden changes in force, thereby enabling smoother valve opening and closing.

[0028] The force application component can also use permanent magnets. Two permanent magnets that repel each other are respectively placed on the piston assembly and the inner wall end face of the driver assembly A. Through the magnetic repulsion between the two permanent magnets, the piston assembly is given the power to move towards the hydraulic cylinder.

[0029] A spring pressure plate 12 is also provided between the piston assembly and the force application assembly. The diameter of the spring pressure plate 12 is larger than the inner diameter of the drive chamber, so that a larger diameter elastic element can be used, especially a first elastic element with a diameter larger than the piston assembly diameter, which can provide greater elastic force and ensure that the piston assembly can be pushed into the drive chamber by the force application assembly. Multiple through holes are evenly provided on the spring pressure plate 12 along the axial direction of the valve stem 21. The through holes are used to balance the pressure on both sides of the spring pressure plate 12. During the linear movement of the spring pressure plate 12, the spatial volume on both sides of the spring pressure plate 12 changes, and the pressure in the space changes accordingly. Hydraulic oil flows through the through holes to balance the pressure on both sides of the spring pressure plate 12, so that the spring pressure plate 12 can move smoothly under the push of the force application assembly or the piston assembly, ensuring that the preparation valve assembly B can be opened or closed smoothly.

[0030] A wear-resistant ring is provided on the outer diameter of the spring pressure plate 12 to prevent friction between the spring pressure plate 12 and the inner wall of the actuator body 16 during valve opening and closing. The spring pressure plate 12 has two stepped surfaces on the side facing the force application component. The two stepped surfaces contact the inner coil spring 15 and the outer coil spring 14 respectively, which can make the force of the two helical springs on the spring pressure plate 12 more balanced during valve assembly and operation.

[0031] A valve stem connector 13 is also provided between the spring pressure plate 12 and the valve stem 21. One end of the valve stem connector 13 is threaded to the valve stem 21, and the other end passes through the spring pressure plate 12 and is connected to the lock nut 11. The length of the valve stem connector 13 is selected according to the length of the valve stem 21 and the formation of the actuator in different types of preparatory valve assemblies B, so as to accommodate more models of preparatory valve assemblies B.

[0032] A retaining ring and a snap ring are provided on the valve stem connector 13 on the side of the locking nut 11 facing the piston assembly to limit the locking nut 11 and prevent it from loosening.

[0033] The actuator is provided with a flow channel. When the actuator is in the first position, the flow channel is disconnected from the inlet and outlet ends of the valve body 22, and the valve assembly B is in the closed state. When the actuator is in the second position, the flow channel is connected to the inlet and outlet ends of the valve body 22, and the valve assembly B is in the open state.

[0034] When the valve assembly B is a gate valve, the actuator can be a gate plate with a through hole as a flow channel. When the gate plate is in the first position, the through hole is disconnected from the inlet and outlet ends of the valve body 22, and the valve assembly B is in the closed state. When the actuator is in the second position, the through hole is connected to the inlet and outlet ends of the valve body 22, and the valve assembly B is in the open state.

[0035] A valve seat 23 is provided between the gate and the inner wall of the valve body 22, and the valve plate 24 is located between the two valve seats 23. The valve seat 23 and the valve plate 24 are sealed by a metal sealing surface.

[0036] The valve stem 21 is detachably connected to the valve plate 24. The valve stem 21 drives the valve plate 24 to move up and down, changing the position of the through hole on the valve plate 24, thereby realizing the opening and closing of the valve. A seal is provided between the valve seat 23 and the valve body 22 to achieve a seal when the valve is closed, ensuring that the medium no longer flows.

[0037] When preparing valve assembly B to be another type of valve, the actuator can also be another corresponding type of valve core. For example, when preparing valve assembly B to be a gate valve, the actuator is the valve core of a gate valve.

[0038] The end of the piston assembly away from the valve stem 21 is connected to the over-control rod 2, which is located inside the over-control interface 1.

[0039] The head of the supercontrol interface 1 is an API 17H standard TYPE-A interface, which is used for valve linear switching. Underwater ROVs or divers use tools to connect to it, thereby pushing the supercontrol rod 2 to drive the piston assembly to move linearly, as an alternative solution for valve switching.

[0040] A pressure cap 3 is installed between the control rod 2 and the control interface 1. A limit ring is provided at the end of the pressure cap 3 facing the hydraulic cylinder 10, and a limit groove is provided at the end of the control interface 1 facing the hydraulic cylinder 10. When the pressure cap 3 is installed into the control interface 1, the limit ring is fixed between the limit groove and the end face of the hydraulic cylinder 10, thus limiting and fixing the pressure cap 3. The inner diameter of the pressure cap 3 is larger than the outer diameter of the control rod 2, forming a channel within the pressure cap 3 for the reciprocating motion of the control rod 2, providing guidance and support during this motion. The pressure cap 3 is equipped with a seal and a wear-resistant ring. The seal prevents marine organisms from entering the valve's internal space in an underwater environment. The inner diameter of the wear-resistant ring is smaller than the inner diameter of the pressure cap 3, preventing friction between the control rod 2 and the pressure cap 3 during reciprocating motion and reducing wear.

[0041] The end of the hydraulic cylinder 10 facing the supercontrol interface 1 is also provided with an upper packing gland 5 and a lower packing gland 6. The supercontrol rod 2 passes through the upper packing gland 5 and the lower packing gland 6. Sealing structures are respectively provided between the upper packing gland 5 and the lower packing gland 6 and the supercontrol rod 2, and between the upper packing gland 5 and the lower packing gland 6 and the hydraulic cylinder 10, to prevent seawater from entering the hydraulic cylinder 10 from between the supercontrol interface 1 and the hydraulic cylinder 10.

[0042] An indicator hole is provided on one side of the control interface 1 along the axial direction of the control rod 2. The control rod 2 is connected to one end of the indicator rod 4, and the other end of the indicator rod 4 passes through the indicator hole. An indicator letter is provided on one side of the indicator hole: open position: 'O', closed position: 'S'. During valve operation, the indicator rod 4 is located in the corresponding position, so the valve status can be determined by the position of the indicator rod 4.

[0043] The piston assembly includes a piston plate 7, a piston 8, and a piston connector 9; the piston 8 has a receiving groove on the side facing the drive chamber, the piston plate 7 has a through hole, one end of the overdrive rod 2 is located in the receiving groove, and the other end passes through the through hole on the piston plate 7 and extends into the overdrive interface 1; the piston plate 7 and the piston 8 are connected by countersunk screws.

[0044] A connecting boss is provided on the side of piston 8 facing the balance chamber. Piston joint 9 has an annular structure. The end of piston joint 9 facing piston 8 is threaded to the connecting boss, and a limiting screw is provided along the radial direction of piston joint 9 to prevent piston joint 9 from rotating relative to piston 8. The end face of piston joint 9 facing spring pressure plate 12 is in contact with spring pressure plate 12. The ends of locking nut 11 and valve stem joint 13 extend into the annular structure of piston joint 9.

[0045] The piston 8 has an upper piston 8 seal, a shaft seal, a wear ring, and a lower piston 8 seal arranged sequentially on its outer diameter. The upper piston 8 seal is used to seal the pressure when the hydraulic control valve is opened, and it is fixed between the piston pressure plate 7 and the piston 8. The lower piston 8 seal is used to seal the hydraulic oil in the actuator body 16 cavity, improving the sealing performance between the drive cavity and the balance cavity. The outer diameter of the wear ring is larger than that of the piston 8 to prevent friction between the piston 8 and the inner wall of the hydraulic cylinder 10, reducing wear. The shaft seal is used for secondary sealing, improving the sealing effect between the piston 8 and the inner wall of the hydraulic cylinder 10.

[0046] The operation process of the subsea Christmas tree valve in this embodiment is as follows: This embodiment of the subsea tree valve has two valve opening methods: 1-hydraulic control opening, 2-opening by an underwater ROV or a diver using a linear operating tool. This invention uses hydraulic control opening as the main opening method.

[0047] During operation, pressure is applied through the first hydraulic control interface on the hydraulic cylinder 10, causing the internal pressure of the hydraulic cylinder 10 to rise continuously. When the valve opening pressure is reached, the force acting on the piston plate 7 and piston 8 slowly pushes it downwards. This force is transmitted to the spring plate 12 through the piston joint 9, compressing the outer spring 14 and inner spring 15, and causing the valve stem joint 13 and valve stem 21 to move downwards together. The valve stem 21 pushes the valve plate 24, which it cooperates with, so that the flow channel on the valve plate 24 gradually aligns with the hole in the valve seat 23, thereby opening the valve and allowing the medium to flow through the flow channel. When the bottom of the valve stem joint 13 is tightly fitted with the gasket on the packing gland 17, the valve is fully open. At the same time, the movement of the piston 8 will drive the movement of the control rod 2, and the indicator rod 4 on the control rod 2 will move from the 'S' position on the control interface 1 to the 'O' position, completing the valve opening operation.

[0048] When the valve is closed, pressure is released from the first hydraulic control interface on the hydraulic cylinder 10. After the pressure is released, the force acting on the piston plate 7 and piston 8 disappears. At this time, the outer spring 14 and inner spring 15 release the compressed force and act on the spring plate 12. Through the locking nut 11, the valve stem connector 13 is driven, which in turn drives the valve stem 21 and valve plate 24 to move. At the same time, the spring plate 12 pushes the piston connector 9, thereby driving the piston 8 to move upward. The over-control rod 2 moves upward as well. When the lower triangular area of ​​the valve stem 21 contacts and fits with the inverted triangular area of ​​the valve cover 20, the indicator rod 4 on the over-control rod 2 is located at the 'S' position of the over-control interface 1. The valve plate 24 completely blocks the hole in the valve seat 23. At this time, the valve closing process ends.

[0049] When the hydraulic opening device fails, an underwater ROV or diver can use a linear opening tool to apply sufficient force to the control rod 2 through the interface on the control interface 1, thereby pushing the piston 8 downward and pushing the spring pressure plate 12 to compress the outer spring 14 and the inner spring 15, opening the valve. The tool can be locked on the control interface 1 and can be unlocked and removed when the valve needs to be closed.

[0050] It should be noted that, for those skilled in the art, it is obvious that the present invention is not limited to the details of the above exemplary embodiments, and that the present invention can be implemented in other specific forms without departing from the spirit or essential characteristics of the invention. Therefore, the embodiments should be considered exemplary and non-limiting in all respects, and the scope of the invention is defined by the appended claims rather than the foregoing description. Thus, all variations falling within the meaning and scope of equivalents of the claims are intended to be included within the present invention, and no reference numerals in the claims should be construed as limiting the scope of the claims.

[0051] This specification uses specific examples to illustrate the principles and implementation methods of the present invention. The descriptions of the above embodiments are only for the purpose of helping to understand the method and core ideas of the present invention. Furthermore, those skilled in the art will recognize that, based on the ideas of the present invention, there will be changes in the specific implementation methods and application scope. Therefore, the content of this specification should not be construed as a limitation of the present invention.

Claims

1. An underwater failure shut-off valve, characterized in that, include: A drive assembly (A) includes a piston assembly that divides the interior of the drive assembly (A) into an independent drive chamber and a balance chamber. A first hydraulic port is provided at the end of the drive chamber away from the balance chamber, and a second hydraulic port is provided at the end of the balance chamber away from the drive chamber. The first hydraulic port and the second hydraulic port are hydraulically connected to the outside of the drive assembly (A). The piston assembly is drivenly connected to one end of a valve stem (21). A force-applying component is provided between the piston assembly and the inner wall end face of the drive assembly (A). The force-applying component can apply a force to the piston assembly in the axial direction of the valve stem, and the direction of the force is from the balance chamber to the drive chamber. The preparation valve assembly (B) includes a valve body (22), and an actuator is provided inside the valve body (22). Along the axial direction of the valve stem (21), the actuator has a first position and a second position. When the actuator is in the first position, the preparation valve assembly (B) is in a closed state. When the actuator is in the second position, the preparation valve assembly (B) is in an open state. The actuator is connected to one end of the valve stem (21).

2. The underwater failure shut-off valve according to claim 1, characterized in that, The drive assembly (A) includes a drive body (16), which is connected to the valve body (22) via a valve cover (20). A hydraulic cylinder (10) is provided at one end of the drive body (16) away from the valve cover (20). The piston assembly is slidably disposed in the hydraulic cylinder (10). The force application assembly is disposed between the piston assembly and the valve cover (20).

3. The underwater failure shut-off valve according to claim 2, characterized in that, A packing gland (3) is provided between the valve stem (21) and the valve cover (20). At least two sealing rings are provided between the packing gland (3) and the valve cover (20). A relief valve (18) is provided on the valve cover (20). The two sealing rings are connected to the relief valve (18) through a pressure relief channel.

4. The underwater failure shut-off valve according to claim 1, characterized in that, The force-applying component includes a first elastic element and a second elastic element, which are coaxially arranged with the valve stem (21).

5. The underwater failure shut-off valve according to claim 4, characterized in that, A spring pressure plate (12) is also provided between the piston assembly and the force application assembly. The diameter of the spring pressure plate (12) is larger than the inner diameter of the drive cavity. At least one through hole is provided on the spring pressure plate (12) along the axial direction of the valve stem (21).

6. The underwater failure shut-off valve according to claim 5, characterized in that, A valve stem connector (13) is also provided between the spring pressure plate (12) and the valve stem (21). One end of the valve stem connector (13) is threaded to the valve stem (21), and the other end passes through the spring pressure plate (12) and is connected to the lock nut (11).

7. The underwater failure shut-off valve according to claim 4, characterized in that, Both the first elastic element and the second elastic element are helical springs, and the first elastic element and the second elastic element have opposite directions of rotation.

8. The underwater failure shut-off valve according to claim 1, characterized in that, The actuator is provided with a flow channel. When the actuator is in the first position, the flow channel is disconnected from the inlet and outlet ends of the valve body (22), and the preparation valve assembly (B) is in the closed state. When the actuator is in the second position, the flow channel is connected to the inlet and outlet ends of the valve body (22), and the preparation valve assembly (B) is in the open state.

9. The underwater failure shut-off valve according to claim 1, characterized in that, The end of the piston assembly away from the valve stem (21) is connected to the over-control rod (2), which is located inside the over-control interface (1).

10. The underwater failure shut-off valve according to claim 9, characterized in that, An indicator hole is provided on one side of the super control interface (1) along the axial direction of the super control rod (2). The super control rod (2) is connected to one end of the indicator rod (4), and the other end of the indicator rod (4) passes through the indicator hole.

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