A closed isolation valve and method of use thereof

Abstract

The application relates to a closed isolation valve and a use method thereof, which comprises a valve body and a valve core, the valve body comprises a valve body cylinder and valve body end plates fixed at both ends of the valve body cylinder, the valve core comprises a valve core fixedly connected in the valve body cylinder and valve core end plates fixed at both ends of a valve core cavity, switch shafts extending to the outside of the valve body are fixed on the valve core end plates, the valve core and the switch shafts are coaxially arranged, the switch shafts are coaxially arranged with the valve body cylinder, inlet and outlet assemblies are communicated on the circumferential surface of the valve body cylinder, the valve body is split arranged, the valve core can be taken out from the valve body end, the valve core is convenient to disassemble, maintain and replace, and closed cavities are formed between the closed sealing rings on the two sides of the valve body and valve body end covers, the valve body end plates are provided with closed sealing holes, and the valve body cylinder is provided with isolation sealing doors, so that internal leakage is prevented and the sealing effect is good.

Description

Technical Field

[0001] This invention relates to the field of valves, specifically to a closed isolation valve and its usage method. Background Technology

[0002] Valves are components used to switch fluids on and off. They generally include gate valves, globe valves, and ball valves. A ball valve typically consists of a valve body with a fixed valve seat inside. A spherical valve core resides within the valve seat. The ball valve opens when the through-hole of the valve core is coaxial with the valve body, and closes when the through-hole is perpendicular to the valve body's axis. The valve core rubs against the valve seat during rotation, and wear on the valve seat reduces its sealing performance. Maintaining the valve seat is relatively inconvenient, especially for ball valves manufactured using a fully welded process; once the seal fails, the ball valve is rendered unusable.

[0003] The invention disclosed in the authorization announcement number CN 216975850 U is a ball valve that can reliably contact the left and right valve seats with the valve core by adjusting the nut on the bolt, resulting in small assembly errors. After the ball valve wears out, the wear gap can be repaired by adjusting the nut on the bolt, without the need to install or remove the ball valve. However, this ball valve still uses the original ball valve structure, which makes maintenance and installation inconvenient and has poor expansion capabilities. Summary of the Invention

[0004] This invention addresses the shortcomings of existing technologies by providing a closed isolation valve and its usage method that are simple in structure, easy to process, reliable in structure, and convenient in operation.

[0005] This invention is achieved through the following technical solution: a closed isolation valve is provided, comprising a valve body and a valve core. The valve body includes a valve body cylinder and valve body end plates fixed to both ends of the valve body cylinder. The valve core includes a valve core rotatably connected inside the valve body cylinder and valve core end plates fixed to both ends of the valve core chamber. A switch shaft extending out of the valve body is fixedly connected to the valve core end plates. The valve core and the switch shaft are coaxially arranged, and the switch shaft and the valve body cylinder are coaxially arranged. An inlet and outlet assembly is connected to the circumferential surface of the valve body cylinder. The inlet and outlet assembly includes two oppositely arranged inlet and outlet pipes. A pipe through-channel adapted to the two inlet and outlet pipes is opened on the valve core chamber. A sealing sleeve adapted to the opening of the through-channel is fixedly connected inside the inlet and outlet pipes.

[0006] In this design, the rotation of the switch shaft causes the valve core to rotate within the valve body. When the two ends of the through-channel of the valve core chamber correspond to the two inlet and outlet pipes of the inlet and outlet assembly, the valve is open. When the two ends of the through-channel of the valve core chamber are misaligned with the two inlet and outlet pipes of the inlet and outlet assembly, the valve is closed, and the sealing sleeve fits into the opening of the through-channel to improve the sealing effect.

[0007] As an optimization, both the valve core and the valve body cylinder are of equal diameter, and the valve core also includes a central filter screen fixedly attached to the valve core chamber. In this design, the central filter screen filters the fluid flowing through the through-channel.

[0008] As an optimization, the through channel includes two connecting ports opened on the circumferential surface of the valve core chamber, with the two connecting ports arranged opposite to each other.

[0009] As an optimization, a pressure relief detection gate and an isolation sealing gate are connected to the circumferential surface of the valve body cylinder. Both the pressure relief detection gate and the isolation sealing gate are staggered circumferentially with the inlet and outlet pipes. In this design, when the valve is closed, the pressure relief detection gate can detect whether there is fluid leakage inside the valve, and the isolation sealing gate can inject inert gas into the closed valve body to prevent internal leakage of toxic gases.

[0010] As an optimization, the valve core is tapered, and the end of the sealing sleeve is adapted to the outer tapered surface of the valve core. It also includes a tensioning mechanism for driving the valve core to move axially. The tensioning mechanism drives the valve core to move axially; when the valve is closed, it moves the valve core towards the smaller diameter end to improve the sealing effect; before the valve is opened, it moves the valve core towards the larger diameter end to facilitate rotation of the valve core.

[0011] As an optimization, a switch dial is fixedly connected to the switch shaft, and a scale adapted to the switch dial is fixedly connected to the outside of the valve body end plate. In this design, the switch dial indicates the axial position of the switch shaft on the scale.

[0012] As an optimization, the tensioning mechanism includes an adjusting screw at one end of the switch shaft, with a loosening nut and a tightening nut on the adjusting screw. In this design, the loosening nut tightens the valve core towards the large-diameter end, thereby enabling the valve core to rotate, while the tightening nut tightens the valve core towards the small-diameter end, thereby achieving a seal on the valve core.

[0013] As an optimization, the tensioning mechanism includes a piston fixed to the small-diameter end of the valve core. The outer ring of the piston and the outer ring of the large-diameter end of the valve core are both equipped with piston rings that fit against the inner wall of the valve body cylinder. The side of the piston away from the valve core forms a sealed loosening chamber, and the side of the large-diameter end of the valve core away from the valve core forms a sealed tightening chamber. The tensioning mechanism includes a small-diameter oil inlet pipe communicating with the loosening chamber and a large-diameter oil inlet pipe communicating with the tightening chamber.

[0014] Injecting high-pressure fluid into the loosening chamber through the small-diameter inlet pipe can push the valve core towards the large-diameter end, thereby enabling the valve core to rotate. Injecting high-pressure fluid into the tightening chamber through the large-diameter inlet pipe can push the valve core towards the small-diameter end, thereby achieving a seal on the valve core.

[0015] As an optimization, valve body flanges are fixedly connected to both ends of the valve body cylinder, and the valve body end plate is connected to the valve body flanges by bolts. In this solution, valve body flanges are fixedly connected to both ends of the valve body cylinder, and the valve body end plate is connected to the valve body flanges by bolts, thereby facilitating the disassembly and assembly of the valve core tube.

[0016] As an optimized design, the valve body end plate is connected to the valve body cylinder by screwing on the internal thread end cap and the external thread at both ends.

[0017] A method for using a closed isolation valve:

[0018] The valve core rotates within the valve body by rotating the switch shaft. When the through passage of the valve core chamber corresponds to the two inlet and outlet pipes of the inlet and outlet assembly, the valve body is turned on.

[0019] The valve closes when the through-pipe passage of the valve core chamber is misaligned with the two inlet and outlet pipes of the inlet and outlet assembly;

[0020] The valve core is conical and is driven to move axially by a tensioning mechanism. When the valve is closed, the valve core moves towards the smaller diameter end to improve the sealing effect; when the valve is opened, the valve core moves towards the larger diameter end to facilitate the rotation of the valve core tube.

[0021] The beneficial effects of the present invention are as follows: The present invention provides a rotary sleeve valve and its method of use. The valve core rotates within the valve body. When the through-channel of the core corresponds to the two inlet and outlet pipes of the inlet and outlet assembly, the valve opens. When the through-channel of the valve core is misaligned with the two inlet and outlet pipes of the inlet and outlet assembly, the valve closes. Furthermore, the valve body in the present invention is a split design, and the valve core can be removed from the end of the valve body, which facilitates the disassembly and maintenance of the valve core. Attached Figure Description

[0022] Figure 1 This is a cross-sectional structural diagram of Embodiment 1 of the present invention;

[0023] Figure 2 As in Embodiment 1 of the present invention Figure 1 Sectional view of plane AA;

[0024] Figure 3 For the present invention Figure 1 The right view;

[0025] Figure 4 This is a cross-sectional structural diagram of Embodiment 3 of the present invention;

[0026] Figure 5 This is a cross-sectional structural diagram of Embodiment 2 of the present invention;

[0027] Figure 6 This is Example 4 of the present invention. Figure 1 Sectional view of plane AA;

[0028] Figure 7 This is Example 5 of the present invention. Figure 1 Sectional view of plane AA;

[0029] Figure 8 These are schematic diagrams showing four possible shapes of the communication port of this invention;

[0030] Figure 9 This is a cross-sectional structural diagram of Embodiment 6 of the present invention;

[0031] Figure 10 This is a cross-sectional structural diagram of Embodiment 7 of the present invention;

[0032] Figure 11 This is a cross-sectional structural diagram of Embodiment 8 of the present invention;

[0033] Figure 12 , 13 This is a cross-sectional structural diagram of Embodiment 9 of the present invention;

[0034] Figure 14 This is a cross-sectional structural diagram of Embodiment 10 of the present invention:

[0035] As shown in the figure:

[0036] 1. Valve body cylinder; 2. Inlet / outlet pipes; 3. Inlet / outlet flanges; 4. Sealing sleeve; 5. Valve core; 6. Valve core end plate; 7. Switch shaft; 8. Valve body; 9. Central filter screen; 10. Valve body end plate; 11. Valve body flange; 12. Packing; 13. Sealing gasket; 14. Connecting port; 15. Tightening nut; 16. Loosening nut; 17. Switch dial; 18. Scale; 19. Piston; 20. Bearing housing; 21. Valve core sealing ring; 22. Small diameter inlet pipe; 23. Large diameter inlet pipe; 24. Spring; 25. Thrust bearing; 26. Pressure relief detection door; 27. Isolation sealing door; 28. Sealing hole; 29. ​​Valve core chamber; 30. Sealing ring. Detailed Implementation

[0037] To clearly illustrate the technical features of this solution, the following detailed implementation method will be used to explain the solution.

[0038] Example 1:

[0039] like Figures 1-3 As shown, a closed isolation valve of the present invention includes a valve body and a valve core. The valve body includes a valve body cylinder 1 and valve body end plates 10 fixed to both ends of the valve body cylinder 1. In this embodiment, valve body flanges 11 are fixed to both ends of the valve body cylinder 1. The valve body end plates 10 are connected to the valve body flanges 11 by bolts, thereby realizing the disassembly and assembly of the internal valve core. The valve body cylinder 1 is a circular cylinder of equal diameter, with the diameter being equal at all points.

[0040] The valve core includes a valve core 5 rotatably connected within the valve body cylinder 1 and valve core end plates 6 fixed to both ends of the valve core chamber 29. The valve core end plates 6 are welded to the ends of the valve core chamber 29, achieving closure at both ends of the valve core chamber 29. The valve core 5 is a cylinder of equal diameter, with the diameter being the same at all points. A switch shaft 7 extending out of the valve body is fixedly connected to the center of the valve core end plate 6, thereby achieving a rotatable connection of the valve core 5 within the valve body cylinder 1. The valve core 5 and the switch shaft 7 are coaxially arranged, and the switch shaft 7 is coaxially arranged with the valve body cylinder 1.

[0041] The valve body end plate 10 is equipped with a bearing that supports the switch shaft 7. A bearing cover is installed on the side of the bearing bracket away from the valve body end plate 10. The bearing cover is connected to the valve body end plate 10 by bolts, which facilitates the disassembly and maintenance of the bearing.

[0042] Valve body end plate 10 Figure 1 At the flange connection, it can also be used Figure 14 It uses a threaded connection and has a sealing ring on the inside.

[0043] The switch shaft 7 passes through the through hole of the valve body end plate 10 and is fitted with packing 12, which serves as a seal.

[0044] The valve body cylinder 1 has an inlet and outlet assembly connected to its circumferential surface. The inlet and outlet assembly includes two oppositely arranged inlet and outlet pipes 2. In this embodiment, a pair of inlet and outlet assemblies are provided. The inlet and outlet pipes 2 are connected to the circumferential surface of the valve body cylinder 1. This closed isolation valve is used to realize the connection and disconnection of the two inlet and outlet pipes 2.

[0045] The inlet / outlet pipe 2 is fixedly connected to an inlet / outlet flange 3 at the end away from the valve body cylinder 1 for connecting the inlet / outlet pipe 2 to external pipelines. A sealing sleeve 4 adapted to the opening of the through channel is fixedly connected inside the inlet / outlet pipe 2. The sealing sleeve 4 is bolted to the inlet / outlet pipe 2, and an elastic sleeve is installed between the sealing sleeve 4 and the inlet / outlet pipe 2, so that the sealing sleeve 4 can be axially spaced at a certain distance to improve the sealing ability.

[0046] The valve core chamber 29 has a through channel adapted to the two inlet and outlet pipes 2. The through channel includes two connecting ports 14 on the circumferential surface of the valve core chamber 29, which are arranged opposite to each other. The diameter of the connecting ports 14 is not greater than the inner diameter of the inlet and outlet pipes 2. Valve core tube sealing rings 21 are provided at both ends of the through channel of the valve core chamber.

[0047] The valve opening is proportional to the flow rate. For example... Figure 8 As shown, the connecting port 14 can be designed in a square shape ( ). Figure 8 (Top left corner), Connector 14 can also be designed as a convex shape ( Figure 8 (lower left corner), sun shape () Figure 8 (top right corner), mountain-shaped ( Figure 8(e.g., lower right corner) are designed in different shapes according to the requirements of flow regulation, with priority given to high flow through holes, such as elliptical holes, to prevent flow interception.

[0048] The valve core also includes a central filter 9 fixedly attached within the valve core chamber 29. The central filter 9 can be configured as follows: Figure 1 The device has two layers, with a sealing gasket 13 installed between one end of the central filter 9 and the valve core end plate 6. The valve core end plate 6, which is close to the sealing gasket 13, is removable, making it easy to replace the central filter 9 or remove and clean it.

[0049] The central filter 9 can also be like Figure 2 As shown, set one layer.

[0050] The switch shaft 7 can be rotated manually or with a power tool. The rotation of the switch shaft 7 causes the valve core to rotate within the valve body. When the through-channel port 14 of the valve core corresponds to the two inlet and outlet pipes 2 of the inlet and outlet assembly, the valve body is open. When the through-channel port 14 of the valve core 5 is misaligned with the two inlet and outlet pipes 2 of the inlet and outlet assembly, the valve body is closed. The valve core can be disassembled and assembled by removing the valve body end plate 10 at the end of the valve body cylinder 1.

[0051] Example 2:

[0052] like Figure 5 As shown, the difference between this embodiment and Embodiment 1 is that:

[0053] The valve core 5 is conical, and the end of the sealing sleeve 4 is adapted to the outer conical surface of the valve core 5, thereby achieving a tight seal with the conical surface.

[0054] It also includes a tensioning mechanism for driving the valve core 5 to move axially. In this embodiment, the tensioning mechanism includes an adjusting screw at one end of the switch shaft 7, and a loosening nut 16 and a tightening nut 15 on the adjusting screw. The switch shaft 7 is a through shaft that passes through the valve body, and a bolt mounting bracket is fixed to the outer side of one valve body end plate 10. The loosening nut 16 and the tightening nut 15 are respectively threaded onto the bolt mounting bracket.

[0055] By tightening the loosening nut 16 and loosening the tightening nut 15, the valve core 5 is moved toward the large diameter end, which facilitates the rotation of the valve core 5.

[0056] By tightening the nut 15 and loosening the nut 16, the valve core 5 moves towards the smaller diameter end, improving the sealing effect.

[0057] A switch dial 17 is fixedly connected to the switch shaft 7. The switch dial 17 is a circular wheel with a conical outer ring. A scale 18 adapted to the switch dial 17 is fixedly connected to the outer side of the valve body end plate 10. The scale 18 extends axially along the switch shaft 7, and the conical tip of the switch dial 17 points to the scale 18, thereby displaying the axial position of the switch shaft 7.

[0058] Example 3:

[0059] like Figure 4 As shown, the difference between this embodiment and Embodiment 2 is that:

[0060] The tensioning mechanism includes a piston 19 fixed to the small-diameter end of the valve core 5. The outer ring of the piston 19 and the outer ring of the large-diameter end of the valve core tube 5 are both equipped with piston rings that fit against the inner wall of the valve body tube 1. The side of the piston 19 away from the valve core 5 forms a closed loosening chamber, and the side of the large-diameter end of the valve core 5 away from the valve core 5 forms a closed tightening chamber. The tensioning mechanism includes a small-diameter oil inlet pipe 22 that communicates with the loosening chamber and a large-diameter oil inlet pipe 23 that communicates with the tightening chamber.

[0061] Injecting high-pressure fluid into the loosening chamber through the small-diameter inlet pipe can push the valve core towards the large-diameter end, thereby enabling the valve core to rotate. Injecting high-pressure fluid into the tightening chamber through the large-diameter inlet pipe can push the valve core towards the small-diameter end, thereby achieving a seal on the valve core.

[0062] A bearing housing 20 is fixed to the outside of the valve body end plate 10, and a thrust bearing 25 is installed inside the bearing housing 20 at the large diameter end of the valve core 5.

[0063] A spring 24 is installed at one end of the switch shaft 7 near the small diameter end of the valve core tube 5. A protrusion is installed on the switch shaft 7. The spring 24 presses against the protrusion and pushes the switch shaft 7 toward the large diameter end, thereby facilitating the rotation of the valve core.

[0064] A method for using a rotary sleeve valve:

[0065] The valve core rotates within the valve body by the rotation of the switch shaft 7. When the through passage 14 of the valve core chamber 29 corresponds to the two inlet and outlet pipes 2 of the inlet and outlet assembly, the valve body is turned on.

[0066] When the through passage 14 of the valve core chamber 29 is misaligned with the two inlet and outlet pipes 2 of the inlet and outlet assembly, the valve body closes.

[0067] The valve core 5 is conical. The valve core 5 is driven to move axially through the tensioning mechanism. After the valve body is closed, the valve core 5 moves to the small diameter end to improve the sealing effect. Before the valve body is opened, the valve core 5 moves to the large diameter end to facilitate the rotation of the valve core 5.

[0068] Example 4:

[0069] like Figure 6 As shown, the difference between this embodiment and Embodiment 1 is that:

[0070] The inlet and outlet components are provided in two and are arranged vertically. When the two inlet and outlet pipes in one inlet and outlet component are connected, the two inlet and outlet pipes in the other inlet and outlet component are disconnected, thereby realizing the separate opening and closing of the two pipelines.

[0071] Example 5:

[0072] like Figure 7 As shown, the difference between this embodiment and Embodiment 1 is that:

[0073] The circumferential surface of the valve body cylinder 1 is connected to a pressure relief detection door 26 and an isolation sealing door 27. The pressure relief detection door 26 and the isolation sealing door 27 are both circumferentially staggered with the inlet and outlet pipes 2. In this embodiment, the pressure relief detection door 26 and the isolation sealing door 27 are located on both sides of the valve body cylinder 1, and the line connecting the pressure relief detection door 26 and the isolation sealing door 27 is perpendicular to the line connecting the two inlet and outlet pipes 2. When the valve is closed, the pressure relief detection door can detect whether there is fluid leakage inside the valve, and the isolation sealing door can inject inert gas into the closed valve to prevent internal leakage of the transported fluid.

[0074] Example 6:

[0075] like Figure 9 As shown, the difference between this embodiment and Embodiment 1 is that:

[0076] The switch shaft 7 is disconnected inside the valve core and has no central filter screen 9. It is used for washing and abrading solid materials such as ash, slag, coal, and cement.

[0077] Example 7:

[0078] like Figure 10 As shown, the difference between this embodiment and Embodiment 1 is that:

[0079] The switch shaft has an eccentric structure. Specifically, in the closed state, the valve core is eccentric and closer to the valve inlet. Thus, when the valve needs to be closed, the eccentricity allows the valve inlet to fit better against the outer wall of the valve core, compensating for poor sealing caused by wear and achieving the advantages of good sealing effect and long service life.

[0080] Meanwhile, to ensure sealing, multiple seals can be provided on the outside of the valve core, i.e., the inside of the valve body cylinder, to guarantee sealing performance.

[0081] Figure 10 In this system, the medium flows in from the top and then out from the bottom. To ensure a tight seal, sealing rings 30 are provided between the valve core and the valve body cylinder on both sides, and sealing holes 28 are provided on the end plates on both sides of the valve body. A closed chamber is formed between the sealing rings 30 and the end cover packing. The sealing medium is injected into the closed chamber through the sealing holes 28 to form a tight seal and prevent the conveyed fluid from leaking along the shaft.

[0082] When closed, it can be rotated manually. Figure 10 The handle on the far right can be turned to directly seal the inlet and outlet. To achieve automation and ease of control, manual turning can be replaced with electric turning.

[0083] Example 8:

[0084] Figure 11 As shown, the difference between this embodiment and Embodiment 1 is that:

[0085] The valve body tube 1 has multiple inlets and outlets. At the same time, the outer wall of the valve core 5 also has multiple corresponding through holes. When the valve core 5 rotates, the through holes on different valve core 5 correspond to the openings on the valve body cylinder to realize the functions of switching on and off and reversing. For example, this embodiment has four ports, two at the top and two at the bottom. Then, four openings can be provided on the outer wall of the valve core 5. The four openings can correspond to different positions to realize reversing or switching on and off.

[0086] Example 9:

[0087] Figure 12 As shown, in this embodiment, the array has three inlets and outlets, and the valve core tube 5 has two outlets. The other end is a blind end, which can realize one inlet and one outlet, and realize left and right reversal.

[0088] Figure 13 for Figure 12 The three inlets and outlets were modified to be located at the top, left, and right positions, and the cross-section of the valve core 5 was also designed to simultaneously open two adjacent openings and close the other port.

[0089] Implementation List 10:

[0090] like Figure 14 As shown, the difference between this embodiment and Embodiment 1 is that:

[0091] The valve body end cap is designed to be an internally threaded end cap that is screwed tightly to the external threads at both ends of the valve body cylinder. Furthermore, the valve body end cap contains a sealing gasket, and a sealing ring is provided between the valve body end cap and the shaft.

[0092] Of course, the above description is not limited to the examples above. Technical features not described in this invention can be implemented by or using existing technology, and will not be repeated here. The above embodiments and drawings are only used to illustrate the technical solutions of this invention and are not intended to limit this invention. This invention has been described in detail with reference to preferred embodiments. Those skilled in the art should understand that any changes, modifications, additions or substitutions made by those skilled in the art within the scope of this invention do not depart from the spirit of this invention and should also fall within the scope of protection of the claims of this invention.

Claims

1. A closed isolation valve, characterized by: The valve body includes a valve body cylinder (1) and valve body end plates (10) fixed at both ends of the valve body cylinder (1), and the valve core includes a valve core (5) rotatably connected in the valve body cylinder (1) and valve core end plates (6) fixed at both ends of a valve core chamber (29), the valve core end plates (6) are fixed with switch shafts (7) extending to the outside of the valve body, the valve core (5) rotates synchronously with the switch shafts (7), the circumferential surface of the valve body cylinder (1) is communicated with an inlet and outlet assembly, the inlet and outlet assembly includes at least two arranged inlet and outlet pipes (2), the valve core chamber (29) is provided with through channels adapted to the two inlet and outlet pipes (2), and the inlet and outlet pipes (2) are fixed with sealing sleeves (4) adapted to the openings of the through channels. The through channels include two communication openings (14) arranged on the circumferential surface of the valve core chamber (29), and the two communication openings (14) are oppositely arranged. The valve core (5) and the valve body cylinder are conical structures matched with each other, the end of the sealing sleeve (4) is adapted to the outer conical surface of the valve core (5), and the valve core further includes a central filter screen (9) fixed in the valve core chamber (29), a sealing gasket (13) is arranged between one end of the central filter screen (9) and the valve core end plate (6), and the valve core end plate (6) close to the sealing gasket (13) is detachable, so that the central filter screen (9) can be replaced or taken out for cleaning. The circumferential surface of the valve body cylinder (1) is communicated with a pressure relief detection door (26) and an isolation sealing door (27), the pressure relief detection door (26) and the isolation sealing door (27) are circumferentially staggered with the inlet and outlet pipes (2) and are located on both sides of the valve body cylinder (1) respectively, and the connecting line of the pressure relief detection door (26) and the isolation sealing door (27) is perpendicular to the connecting line of the two inlet and outlet pipes (2). The pressure relief detection door can detect whether there is fluid leakage in the valve when the valve is closed, and the isolation sealing door can inject inert gas into the closed valve to prevent leakage of the conveying fluid.

2. A closed isolating valve according to claim 1, characterized in that: A closed sealing ring (30) is arranged between the valve core and the valve body cylinder, and a closed sealing hole (28) is arranged on the end plate of the valve body.

3. A closed isolating valve according to claim 1, characterized in that: The outer wall of the valve core (5) and the inner wall of the valve body cylinder (1) are designed with the same diameter. The tensioning mechanism includes a loose nut (16) and a tight nut (15) arranged at one end of the switch shaft (7).

4. A closed isolating valve according to any one of claims 1-3, characterized in that: The valve body flange (11) is fixed to both ends of the valve body cylinder (1), and the valve body end plate (10) is connected to the valve body flange (11) by bolts.

5. The closed isolation valve of claim 1, wherein: The valve core and the switch shaft are eccentric shaft matching structures, and the eccentric distal end of the outer wall of the valve core is closer to the inlet position of the valve in the closed state, and is used for plugging the inlet.

6. The use method of the closed isolation valve according to claim 1 or 5, characterized in that: Through the rotation of the switch shaft (7), the valve core rotates in the valve body, when the communication port (14) of the valve core chamber (29) corresponds to the two inlet and outlet pipes (2) of the inlet and outlet assembly respectively, the valve body is conducted; When the communication port (14) of the valve core chamber (29) is staggered with the two inlet and outlet pipes (2) of the inlet and outlet assembly, the valve body is closed; Through the tensioning mechanism, the valve core (5) is driven to move axially, the valve core (5) moves to the small diameter end after the valve body is closed, and the sealing effect is improved; the valve core (5) moves to the large diameter end before the valve body is opened, and the rotation of the valve core (5) is facilitated; The two sides of the valve body and the valve core are provided with closed sealing rings (30), the valve body end cover is provided with a closed sealing hole (28), the closed medium is injected into the closed sealing hole, the closed sealing is formed, and the leakage of the conveying fluid along the shaft is prevented; The isolation sealing door (27) is arranged circumferentially staggered with the inlet and outlet pipes, the isolation sealing medium is injected into the valve core chamber (29) of the closed isolation valve, the conveying fluid is cut off, and the valve leakage is prevented.

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