Pressure protection cut-off valve and fluid system

Abstract

The invention belongs to the related technical field of valves, and discloses a pressure protection cut-off valve and a fluid system.The pressure protection cut-off valve comprises a valve element movement unit and a pressure isolation assembly movably connected with the valve element movement unit; an expansion cavity is formed between the pressure isolation assembly and the valve element movement unit, the volume of the expansion cavity changes along with the pressure of a working medium of the inlet channel, and the expansion cavity for pressure induction is arranged in the valve cavity and communicated with the inlet channel through a circulation groove and a first through hole. The whole structure of the valve is more compact, and the axial size is greatly reduced; meanwhile, only the working medium of the inlet channel flows into the expansion cavity and is not influenced by the working medium of the outlet channel, so that the action of the valve is not influenced by the working medium of the outlet channel, the interference of the outlet pressure on the action of the valve core is eliminated, and the action precision of the valve is further improved; therefore, the axial size of the valve is reduced, and the action precision of the valve is improved.

Description

Technical Field

[0001] This invention belongs to the field of valve-related technology, and more specifically, relates to a pressure protection shut-off valve and fluid system. Background Technology

[0002] Safety shut-off valves are used to quickly cut off the flow path when the system pipeline pressure is abnormal, in order to ensure system safety. However, most existing shut-off valves have the following obvious defects: (i) They usually introduce fluid into the pressure control chamber at the top of the valve to provide the closing power. This design not only results in an excessively large axial dimension of the valve body, but also an overly complex and lengthy internal flow channel. When there are many impurities in the conveyed medium, the flow channel is prone to blockage, leading to valve failure. (ii) The valve core's drive signal is affected by both the inlet and outlet pressures, which makes the valve's action threshold inaccurate, the response characteristics easily affected by downstream operating conditions, and the protection reliability insufficient.

[0003] Those skilled in the art have also conducted some research. For example, Chinese patent CN119146228B discloses a pressure protection shut-off valve, including a valve body, a valve seat fixed to the top of the valve body, a hand disc rotatably mounted on the top of the valve seat, a main valve stem fixed to the bottom of the hand disc and threadedly connected to the valve seat, and a valve core located at the bottom of the main valve stem. The bottom of the main valve stem is provided with a secondary valve stem capable of vertical extension and retraction. The valve core is located at the end of the secondary valve stem and is filled with fluid for synchronously responding to pressure changes within the valve body. When the pressure in the valve cavity exceeds a set value, the pressure protection shut-off valve provided by this patent causes the elastic diaphragm to contract under pressure. This, in turn, causes the fluid in the storage chamber to act on the pneumatic control device, which then feeds back to the actuator. The actuator drives the secondary valve stem to slide downward relative to the main valve stem, thereby achieving pressure protection for the valve body. This solution adopts a layout where the flow path and the medium within the valve body are separated, solving the problem of complex operation in the prior art while avoiding the risk of medium leakage.

[0004] However, the patented solution still has the following shortcomings: (i) The pressure comparison component of the pressure protection shut-off valve uses an elastic diaphragm as the pressure sensing element. This diaphragm can sense the inlet pressure in the valve cavity, but it cannot isolate the outlet pressure, making the valve's operation susceptible to interference from downstream operating conditions. (ii) In order to realize the functions of pressure sensing, signal transmission and shut-off, the valve adopts a multi-layer nested and axially stacked structure, resulting in a large overall axial dimension of the valve. Summary of the Invention

[0005] In view of the above-mentioned defects or improvement needs of the prior art, the present invention provides a pressure protection shut-off valve and fluid system, which aims to solve the problems of large axial dimension and outlet pressure affecting the operation accuracy of existing shut-off valves.

[0006] To achieve the above objectives, according to one aspect of the present invention, a pressure protection shut-off valve is provided. The shut-off valve includes a valve body and a moving assembly. The valve body includes a main body and a valve seat disposed within the main body, the main body forming a valve cavity. The valve seat is connected to the cavity wall of the valve cavity and divides the valve cavity into an upper valve cavity and a lower valve cavity. The cavity wall of the valve cavity is further provided with an inlet channel and an outlet channel, the inlet channel and the outlet channel respectively communicating with the upper valve cavity and the lower valve cavity. The valve seat has a first through hole, the first through hole communicating with the upper valve cavity and the lower valve cavity. The motion assembly includes a valve core motion unit and a pressure isolation assembly movably connected to the valve core motion unit. The pressure isolation assembly and part of the valve core motion unit are suspended in the lower valve cavity. The end of the valve core motion unit away from the pressure isolation assembly is movably connected to the valve seat. An expansion cavity with a volume that changes with the pressure of the working medium in the inlet channel is formed between the pressure isolation assembly and the valve core motion unit. A flow groove is provided at the end of the valve core motion unit facing the first through hole, and the flow groove connects the first through hole and the expansion cavity. The valve core moving assembly can move toward the valve seat or away from the valve seat according to the pressure change of the working medium in the inlet channel, so that the valve core moving assembly abuts against or separates from the valve seat, thereby isolating the inlet channel from the outlet channel or connecting the inlet channel to the outlet channel, and realizing the opening and closing of the valve.

[0007] Furthermore, the valve core moving assembly includes a hollow piston and a combined valve core; the piston rod of the hollow piston is fixedly connected to the combined valve core; a support seat is provided in the upper valve cavity, and a second through hole is opened in the middle of the support seat. One end of the piston rod passes through the second through hole and is connected to the combined valve core, and a movable connection is formed between the piston rod and the second through hole.

[0008] Furthermore, a guide hole is provided at one end of the piston rod connected to the combined valve core, and one end of the pressure isolation component is movably disposed in the guide hole, so that the pressure isolation component and the piston rod are movably connected.

[0009] Furthermore, the pressure isolation assembly includes a valve stem and a valve pot, one end of the valve stem is movably disposed in the guide hole, and the other end is connected to the valve pot; the valve pot is movably connected to the inner wall of the combined valve core, and the expansion cavity is formed between the two.

[0010] Furthermore, the combined valve core has a split structure, which includes a valve core top plate and a valve core base. The valve core top plate and the valve core base are fitted together to form the combined valve core. The valve core base is pot-shaped, and the valve pot is movably connected to the inner wall of the valve core base. The flow groove is formed in the valve core top plate and the valve core base.

[0011] Furthermore, the valve core moving assembly also includes a rubber seal, and a second annular groove is provided at one end of the valve core base adjacent to the valve core top plate, and the rubber seal is embedded in the second annular groove; the valve core moving assembly abuts against the valve seat through the rubber seal.

[0012] Furthermore, the shut-off valve also includes an adjusting mechanism and an elastic element. The two opposite ends of the elastic element are respectively connected to the adjusting mechanism and the hollow piston. The adjusting mechanism is used to adjust the preload of the elastic element.

[0013] Furthermore, the shut-off valve also includes an upper valve body connected to one end of the valve body, one end of the adjusting mechanism extends into the upper valve body and is connected to the elastic element, and the adjusting mechanism and the upper valve body form a threaded connection; the upper valve body is connected to the upper valve cavity.

[0014] Furthermore, the shut-off valve also includes a clamping ring, which is disposed between the upper valve body and the support seat and is press-fitted onto the valve body by an interference fit.

[0015] The present invention also provides a fluid system in which a pressure protection shut-off valve as described above is provided on the pipeline of the fluid system.

[0016] In summary, compared with the prior art, the pressure protection shut-off valve and fluid system provided by the present invention have the following advantages: 1. An expansion chamber with a volume that varies with the pressure of the working medium in the inlet channel is formed between the pressure isolation component and the valve core movement unit. The pressure-sensing expansion chamber is placed inside the valve cavity and connected to the inlet channel through a flow groove and a first through hole. Compared with the existing method of placing the pressure-sensing chamber outside the valve body, this makes the overall structure of the valve more compact and significantly reduces the axial dimension. At the same time, the working medium flowing into the expansion chamber only flows into the inlet channel and is not affected by the working medium in the outlet channel. This makes the valve's operation unaffected by the working medium in the outlet channel, eliminating the interference of the outlet pressure on the valve core movement, thereby improving the valve's operating accuracy. Thus, the valve's operating accuracy is improved while reducing the axial dimension of the valve.

[0017] 2. The expansion chamber located in the lower valve cavity is formed by the pressure isolation component and the valve core movement unit, and is connected to the inlet channel through the flow groove and the first through hole. This eliminates the need for a long external flow channel. The working medium directly enters the expansion chamber through the flow groove. The flow channel is short and unobstructed, and it is not easy to clog even if the working medium contains impurities, thus improving the reliability of the valve under harsh conditions. At the same time, the pressure-sensing expansion chamber and the movement component are integrated into the design, which minimizes the transmission path of the pressure signal and eliminates intermediate delays, making the valve respond more quickly to pressure changes.

[0018] 3. The expansion chamber only receives the working medium flowing into the inlet channel. This ensures that the valve's set point remains stable regardless of changes in downstream conditions (pressure fluctuations, back pressure changes). It will not malfunction or fail to operate due to outlet pressure fluctuations, thus achieving precise pressure protection. Furthermore, users only need to set the operating value based on the inlet pressure, without needing to consider downstream conditions, making it more convenient to use and maintain.

[0019] 4. The piston rod has a guide hole, and one end of the pressure isolation component is movably disposed in the guide hole. The piston rod is movably connected to the support seat, forming a double guide. The guide hole ensures the coaxiality of the valve rod and the hollow piston, preventing the valve rod from deviating or jamming during reciprocating motion. This ensures that the overall movement trajectory of the moving component is accurate and stable, guaranteeing accurate alignment between the valve core and the valve seat. At the same time, the precise guidance reduces the uneven wear of the sealing ring, making the dynamic seal uniformly stressed, significantly extending the service life of the seal, and reducing the maintenance frequency. The smooth and unbiased movement also ensures that the trajectory of each valve action is consistent, making the opening and closing process predictable and repeatable, and improving the performance consistency of the valve after multiple actions.

[0020] 5. The combined valve core has a split structure, consisting of a valve core top plate and a valve core base that fit together. Both have flow grooves at their upper ends, forming a fluid channel to the expansion chamber after fitting. The split structure reduces the machining difficulty of individual parts, especially the internal flow channel and sealing groove, which is easier to machine and helps ensure machining accuracy. The split structure also allows for the replacement of vulnerable parts such as seals without disassembling the entire valve; only the lock nut needs to be removed for replacement, reducing maintenance costs. The flow groove on the combined valve core keeps the expansion chamber and the inlet channel connected at all times, ensuring that the pressure in the expansion chamber reflects changes in the inlet pressure in real time and without delay, guaranteeing the immediacy of pressure sensing.

[0021] 6. The valve core moving assembly abuts against the valve seat through the rubber seal. The rubber seal is embedded in the second annular groove formed by the two components, which avoids the risk of displacement or dislodgement of the rubber seal during movement. At the same time, the abutment between the rubber seal and the valve seat can reduce impact and better isolate the inlet channel and the outlet channel.

[0022] 7. The adjusting threaded rod is threadedly connected to the upper valve body. By driving the adjusting threaded rod to generate axial displacement relative to the upper valve body, the compression amount of the elastic element is adjusted, and finally the preload of the elastic element is precisely set, that is, the set action pressure of the valve is adjusted.

[0023] 8. When the valve is in operation, if the inlet pressure is abnormal and exceeds the safety threshold set by the elastic element, the valve core moving unit gains an upward net force due to the effective area difference. At the same time, the pressure isolation component generates a downward force under the action of gravity and hydrodynamics. Since the forces are opposite in direction, the combined valve core carrying the rubber seal moves upward, while the valve stem and valve body move downward. The two quickly separate, causing the volume of the expansion chamber to increase sharply. This relative movement eventually causes the rubber seal to tightly abut against the valve seat, realizing the rapid and emergency shut-off of the valve. Attached Figure Description

[0024] Figure 1 This is a cross-sectional view of a pressure protection shut-off valve provided in an embodiment of the present invention; Figure 2 yes Figure 1 A cross-sectional view of the regulating mechanism of the pressure protection shut-off valve in the middle; Figure 3 yes Figure 1 A cross-sectional view of the moving components of the pressure protection shut-off valve in the middle; Figure 4 yes Figure 3 A cross-sectional view of the moving component at another angle; Figure 5 yes Figure 1 A sectional view of the valve body of the pressure protection shut-off valve in the diagram.

[0025] In all the accompanying drawings, the same reference numerals are used to denote the same elements or structures, wherein: 1-valve body, 11-inlet channel, 12-outlet channel, 13-valve cavity, 14-valve seat, 2-upper valve body, 3-adjusting mechanism, 31-adjusting threaded rod, 32-propeller bearing, 33-spring seat, 34-fixing screw, 4-lower end cover, 5-elastic element, 6-pressure ring, 7-support seat, 8-moving component, 81-hollow piston, 811-guide hole, 82-combination valve core, 821-valve core top plate, 822-valve core base, 83-rubber seal, 84-pressure isolation component, 841-valve pot, 842-valve stem, 843-fixing nut, 85-flow groove, 86-expansion cavity, 87-locking nut. Detailed Implementation

[0026] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention. Furthermore, the technical features involved in the various embodiments of this invention described below can be combined with each other as long as they do not conflict with each other.

[0027] Please see Figure 1 This invention provides a pressure-protected shut-off valve, comprising a valve body 1, an upper valve body 2, a lower end cover 4, an adjusting mechanism 3, an elastic element 5, a clamping ring, a support seat 7, and a moving assembly 8. The upper valve body 2 and the lower end cover 4 are respectively connected to opposite ends of the valve body 1. One end of the adjusting mechanism 3 is threadedly connected to the upper valve body 2, and the other end extends into the upper valve body 2 and is connected to one end of the elastic element 5. The other end of the elastic element 5 is connected to one end of the moving assembly 8, and the other end of the moving assembly 8 passes through the clamping ring and the support seat 7 in sequence before extending into the valve body. The clamping ring and the support seat are both disposed within the valve body, and the upper valve body 2, the clamping ring, and the support seat 7 are connected together by bolts.

[0028] Please see Figure 5 The valve body includes a main body and a valve seat 14 disposed within the main body. The main body is cylindrical, and the upper valve body 2 and the end cap are respectively connected to the opposite end openings of the main body to seal the ports at both ends of the main body. The main body forms a valve cavity, and the valve seat 14 is disposed within the valve cavity. An inlet channel 11 and an outlet channel 12 are respectively provided on the side wall of the main body, and both the inlet channel 11 and the outlet channel 12 are connected to the valve cavity. The edge of the valve seat 14 is connected to the side wall of the valve cavity, dividing the valve cavity into an upper valve cavity and a lower valve cavity. The inlet channel 11 and the outlet channel 12 are respectively connected to the upper valve cavity and the lower valve cavity. A first through hole is opened in the middle of the valve seat 14, and the first through hole connects the upper valve cavity and the lower valve cavity. The end of the moving component 8 away from the adjusting mechanism 3 is disposed in the lower valve cavity. In this embodiment, the valve seat 14 is stepped, with the lower end adjacent to the inlet channel 11 and the higher end adjacent to the outlet channel 12; the central axis of the valve cavity coincides with the central axis of the main body, and the central axes of the inlet channel 11 and the outlet channel 12 are both perpendicular to the central axis of the main body.

[0029] The upper valve body 2 is stepped, and its steps are bolted to the end of the main body away from the lower end cover 4. The upper valve body 2 has a first receiving hole for receiving the elastic element 5 and the adjusting mechanism 3. The end of the upper valve body 2 away from the main body has a first threaded hole, and the adjusting mechanism 3 is threadedly connected to the first threaded hole.

[0030] The support base 7 is disposed within the upper valve cavity, and a second through hole is provided in its middle for the moving component 8 to pass through. The clamping ring 6 is disposed between the upper valve body 2 and the support base 7, and is press-fitted onto the valve body by an interference fit to achieve axial fixation of the support base 7. The support base 7 is movably connected to the moving component 8 through the second through hole. Sealing rings are provided between the valve body and the support base 7, and between the support base 7 and the moving component 8, to achieve corresponding static and dynamic sealing.

[0031] Please see Figure 2 The adjusting mechanism 3 includes an adjusting threaded rod 31, a push bearing, a fixing screw 34, and a spring seat 33. The adjusting threaded rod 31 is threadedly connected to the first threaded hole. The spring seat 33 is sleeved inside one end of the elastic element 5, forming a fixed connection. One end of the fixing screw 34 passes through the spring seat 33 and the push bearing and is connected to one end of the adjusting threaded rod 31. The other end of the adjusting threaded rod 31 protrudes from the upper valve body 2 and is provided with a hexagonal nut or a slotted nut to drive the adjusting threaded rod 31 to generate axial displacement relative to the upper valve body 2, thereby driving the spring seat 33 to move synchronously, realizing the adjustment of the compression of the elastic element 5, and ultimately accurately setting the preload of the elastic element 5. The preload directly corresponds to the set operating pressure of the valve.

[0032] The bottom end face of the adjusting threaded rod 31 contacts the upper surface of the thrust bearing 32. The spring seat 33 is U-shaped, with a slot for the thrust bearing 32 in its middle, and the thrust bearing 32 is fitted into the slot. One end of the fixing screw 34 passes through the central shaft holes of the spring seat 33 and the thrust bearing 32 in sequence and connects to the threaded hole at the bottom end of the adjusting threaded rod 31, thereby achieving axial fixation of the three components.

[0033] Please see Figure 3 and Figure 4The moving component 8 includes a hollow piston 81, a combined valve core 82, a rubber seal 83, a pressure isolation component 84, and a locking nut 87. The piston rod of the hollow piston 81 passes through the second through hole and extends into the combined valve core 82, forming a movable connection between the piston rod and the second through hole. The locking nut 87 is threaded to the end of the piston rod that extends into the combined valve core, thereby fixing the hollow piston 81 and the combined valve core 82 together. The hollow piston 81, the rubber seal 83, the combined valve core 82, and the locking nut 87 form a valve core moving unit. The pressure isolation component 84 is movably connected to the valve core moving unit, and an expansion chamber 86 is formed between the combined valve core 82 and the pressure isolation component 84. The volume of the expansion chamber changes with the pressure of the filling fluid.

[0034] The hollow piston 81 guides the movement of the moving component 8 and uses a sealing ring to achieve a dynamic seal at the second through hole of the support 7. One end of the hollow piston 81 has a receiving groove, and the other end is a stepped piston rod. A first annular groove is formed on the bottom surface of the receiving groove, and the other end of the elastic element 5 is disposed within the first annular groove. One end of the piston rod has an external thread, which forms a threaded connection with the locking nut 87. The piston rod has a guide hole 811, which is used to receive part of the pressure isolation component 84, and the piston rod forms a movable connection with the pressure isolation component 84 through the guide hole 811.

[0035] The combined valve core 82 adopts a split design, comprising a valve core top plate 821 and a valve core base 822, which are mated to form the combined valve core 82. The valve core base 822 is pot-shaped, and the piston rod passes through the valve core top plate 821 and the valve core base 822 in sequence before connecting to the locking nut 87. Both the bottom of the valve core top plate 821 and the valve core base 822 have through-flow grooves 85, and the flow grooves on the valve core top plate 821 and the flow grooves 85 on the valve core base 822 correspond in position, forming a connection. The surface of the valve core top plate 821 away from the valve core base 822 mates with the stepped surface of the piston rod to achieve radial positioning.

[0036] The valve core base 822 has a second annular groove at its end, and the rubber seal 83 is embedded in the second annular groove. The valve core moving unit moves relative to the valve seat 14 to make the rubber seal 83 abut against or separate from the valve seat 14, thereby isolating the inlet channel 11 from the outlet channel 12 or connecting the inlet channel 11 to the outlet channel 12, thus realizing the opening and closing of the valve.

[0037] The pressure isolation assembly 84 includes a valve pot 841 and a valve stem 842. The valve pot 841 has a pot-shaped structure, and its edge is slidably connected to the inner wall of the valve core base 822. In this embodiment, the outer diameter of the valve pot 841 is slightly smaller than the inner diameter of the valve core base 822, and a third through hole is provided in the middle of the valve pot 841. One end of the valve stem 842 passes through the third through hole and is slidably disposed in the guide hole 811, while the other end is threadedly connected to the fixing nut 843 via an external thread. A stepped step is formed at the end of the valve stem 842 connected to the fixing nut 843, and the valve pot 841 is fixed on the stepped step, forming a rigid connection between the valve pot 841 and the valve stem 842. A sealing ring is provided at the radial contact mating surface between the valve stem 842 and the valve pot 841 to achieve static sealing. The combined valve core 82 and the pressure isolation assembly 84 form an expansion chamber 86 whose volume changes with fluid pressure. There is no fixed connection at their radial contact surfaces; only a sealing ring is provided to isolate the expansion chamber 86 from the working medium in the outlet flow channel. The flow groove 85 ensures that the working medium from the inlet channel 11 can enter and act on the expansion chamber 86. The pressure of the working medium is the driving source for valve operation.

[0038] When the valve is open, the working medium enters the upper valve chamber through the inlet channel, then enters the lower valve chamber and the expansion chamber 86 through the first through hole. The working medium in the lower valve chamber then flows out of the valve through the outlet channel 12. The working medium enters the expansion chamber 86 through the flow groove 85. When the valve is closed, the rubber seal 83 abuts against the valve seat 14, and the combined valve core closes the first through hole, thus isolating the inlet channel 11 from the outlet channel 12.

[0039] The combined valve core 82 moves upward to its extreme position when the rubber seal 83 abuts against the valve seat 14, at which point the valve is in a closed state and the flow rate in the valve cavity is zero. The combined valve core 82 moves downward to its extreme position when the hollow piston 81 contacts the support base 7, at which point the valve is in a fully open state and the flow rate in the valve cavity is at its maximum.

[0040] During operation, the valve's operating pressure value can be set by changing the pre-compression of the elastic element 5 through the adjusting mechanism 3. In the initial state, under the pre-tightening force of the elastic element 5 and the weight of the moving component 8, the end face of the hollow piston 81 abuts against the support seat 7, and the rubber seal 83 separates from the valve seat 14 to its maximum distance. At this time, the volume of the expansion chamber 86 is at its minimum. The working medium from the inlet channel 11 enters the expansion chamber 86 via the flow groove 85. The pressure of the working medium acts on: 1) the lower surface of the hollow piston 81; 2) the upper and lower surfaces of the combined valve core 82; and 3) the upper surface of the pressure isolation component 84. The outlet working medium pressure acts only on the lower surface of the pressure isolation component 84. When the inlet pressure abnormally increases and exceeds the set value, the pressure inside the expansion chamber 86 increases accordingly, causing the expansion chamber 86 to expand. Under this pressure, the hollow piston 81, the combined valve core 82, and the rubber seal 83 move upward as a whole, while the pressure isolation assembly 84 moves downward. The two move in opposite directions until the rubber seal 83 comes into tight contact with the valve seat 14, cutting off the flow path and achieving pressure protection. When the inlet pressure drops below the set value, the restoring force of the elastic element 5 and the gravity of the moving parts dominate, driving the expansion chamber 86 to contract, pushing the valve core moving unit downward, reopening the valve port, and restoring normal flow.

[0041] The present invention also provides a fluid system in which the above-mentioned pressure protection shut-off valve is installed on the pipeline.

[0042] Those skilled in the art will readily understand that the above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A pressure-protected shut-off valve, characterized in that: The shut-off valve includes a valve body and a moving assembly. The valve body includes a main body and a valve seat disposed within the main body, and the main body forms a valve cavity. The valve seat is connected to the cavity wall of the valve cavity and divides the valve cavity into an upper valve cavity and a lower valve cavity. The cavity wall of the valve cavity is also provided with an inlet channel and an outlet channel, which are respectively connected to the upper valve cavity and the lower valve cavity. The valve seat has a first through hole, which connects the upper valve cavity and the lower valve cavity. The motion assembly includes a valve core motion unit and a pressure isolation assembly movably connected to the valve core motion unit. The pressure isolation assembly and part of the valve core motion unit are suspended in the lower valve cavity. The end of the valve core motion unit away from the pressure isolation assembly is movably connected to the valve seat. An expansion cavity with a volume that changes with the pressure of the working medium in the inlet channel is formed between the pressure isolation assembly and the valve core motion unit. A flow groove is provided at the end of the valve core motion unit facing the first through hole, and the flow groove connects the first through hole and the expansion cavity. The valve core moving assembly can move toward the valve seat or away from the valve seat according to the pressure change of the working medium in the inlet channel, so that the valve core moving assembly abuts against or separates from the valve seat, thereby isolating the inlet channel from the outlet channel or connecting the inlet channel to the outlet channel, and realizing the opening and closing of the valve.

2. The pressure protection shut-off valve as described in claim 1, characterized in that: The valve core moving assembly includes a hollow piston and a combined valve core; the piston rod of the hollow piston is fixedly connected to the combined valve core; a support seat is provided in the upper valve cavity, and a second through hole is opened in the middle of the support seat. One end of the piston rod passes through the second through hole and is connected to the combined valve core, and a movable connection is formed between the piston rod and the second through hole.

3. The pressure protection shut-off valve as described in claim 2, characterized in that: The piston rod is connected to one end of the combined valve core and has a guide hole. One end of the pressure isolation component is movably disposed in the guide hole, so that the pressure isolation component and the piston rod are movably connected.

4. The pressure protection shut-off valve as described in claim 3, characterized in that: The pressure isolation assembly includes a valve stem and a valve pot. One end of the valve stem is movably disposed in the guide hole, and the other end is connected to the valve pot. The valve pot is movably connected to the inner wall of the combined valve core, and the expansion cavity is formed between the two.

5. The pressure protection shut-off valve as described in claim 4, characterized in that: The combined valve core has a split structure, which includes a valve core top plate and a valve core base. The valve core top plate and the valve core base are fitted together to form the combined valve core. The valve core base is pot-shaped, and the valve pot is movably connected to the inner wall of the valve core base. The flow groove is formed in the valve core top plate and the valve core base.

6. The pressure protection shut-off valve as described in claim 5, characterized in that: The valve core moving assembly also includes a rubber seal. A second annular groove is provided at one end of the valve core base adjacent to the valve core top plate, and the rubber seal is embedded in the second annular groove. The valve core moving assembly abuts against the valve seat through the rubber seal.

7. The pressure protection shut-off valve as described in any one of claims 2-6, characterized in that: The shut-off valve also includes an adjusting mechanism and an elastic element. The two opposite ends of the elastic element are respectively connected to the adjusting mechanism and the hollow piston. The adjusting mechanism is used to adjust the preload of the elastic element.

8. The pressure protection shut-off valve as described in claim 7, characterized in that: The shut-off valve further includes an upper valve body connected to one end of the valve body, one end of the adjusting mechanism extends into the upper valve body and is connected to the elastic element, and the adjusting mechanism and the upper valve body form a threaded connection; the upper valve body is connected to the upper valve cavity.

9. The pressure protection shut-off valve as described in claim 8, characterized in that: The shut-off valve also includes a clamping ring, which is disposed between the upper valve body and the support seat and is press-fitted onto the valve body by an interference fit.

10. A fluid system, characterized in that: The fluid system is equipped with a pressure protection shut-off valve as described in any one of claims 1-9 on its pipeline.

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