Blind plate valve

Abstract

The blind plate valve comprises a valve seat and a cut-through assembly, the valve seat is provided with an inlet, an outlet and a channel which is arranged between the inlet and the outlet and communicates with the inlet and the outlet, and the cut-through assembly comprises a cut-through piece, a transmission component and at least three driving units. Wherein the cut-through piece further forms a cut-off part capable of blocking the channel and an annular opening communicated with the channel, and the transmission component is driven by all the driving units to rotationally drive the cut-through piece to rotate until the cut-off part or the annular opening of the cut-through piece is located in the channel. All the driving units are arranged on the valve seat in a central symmetry mode with the center position of the channel as the symmetry center and located on the outer side of the channel so that the gravity centers of at least three or more driving units can be located at the center position of the channel, and therefore the driving units can easily drive the cut-through piece to rotate. And the channel is closed and opened.

Description

Technical Field

[0001] This application relates to the field of valve technology, specifically to blind valves. Background Technology

[0002] Currently, blind flange valves are commonly used in large fluid flow pipeline systems such as blast furnace gas systems. Blind flange valves can control the opening and closing of pipeline flow ports at any time by driving the valve through the drive component, thereby controlling the flow and cut-off of fluid.

[0003] However, in some blind valves, the individual drive components are mostly located at the bottom or on the same side of the pipeline. This makes it easy for the drive center of gravity to deviate from the axis of the flow pipeline. Although this arrangement can make the overall structure of the blind valve stable, the valve itself is generally large in size and weight. Therefore, the drive force required to drive the valve is very large. Conversely, the reaction force on the drive component when driving the valve is also very large. This can easily lead to the failure of the drive component in a short period of time. Therefore, frequent inspection and maintenance of the drive component are required. In particular, when the drive force of the drive component is insufficient, the closing operation will be incomplete when the blind valve needs to close the pipeline flow port, resulting in leakage of the fluid that should have been stopped. Utility Model Content

[0004] To address the aforementioned technical problems and achieve at least one advantage of this application, this application provides a blind valve, the blind valve comprising:

[0005] A valve seat having an inlet, an outlet, and a channel disposed between and communicating with the inlet and the outlet;

[0006] A shut-off assembly includes at least three drive units, a transmission component, and a shut-off member. The at least three drive units are symmetrically arranged on the valve seat with the center of the channel as their center of symmetry, and are located outside the channel, so that the center of gravity of the at least three drive units is located at the center of the channel. The transmission component, driven by the at least three drive units, rotates the shut-off member until the shut-off member is at least partially located within the channel. The shut-off member also forms a flow-blocking section with a cross-sectional area not less than the cross-sectional area of ​​the channel. The distance between the center of the cut-off section and the center of the circle formed by the rotation of the cut-off member is equal to the distance between the axis of the channel and the center of the circle formed by the rotation of the cut-off member. Thus, when the cut-off section is completely located in the channel, the cut-off section closes the channel. The cut-off member also forms an annular opening with a cross-sectional area not greater than the cross-sectional area of ​​the channel. The distance between the center of the annular opening and the center of the circle formed by the rotation of the cut-off member is equal to the distance between the center of the cut-off section and the center of the circle formed by the rotation of the cut-off member. Thus, when the annular opening is completely located in the channel, the annular opening communicates with the channel to open the channel.

[0007] According to one embodiment of this application, the transmission component includes the same number of first transmission members and second transmission members as the drive unit, wherein one of the first transmission members is synchronously rotatably connected to one of the drive units, and each of the first transmission members is also rotatably connected to the valve seat, the shut-off member is connected to one of the first transmission members, and the second transmission member is rollably engaged with the other end of each of the first transmission members in a manner surrounding the outside of the channel.

[0008] According to one embodiment of this application, the number of driving units is set to three, and the three driving units are distributed evenly and at intervals on the outside of the channel, and the lines connecting each pair of the three driving units form an equilateral triangle. The number of first transmission members is also set to three, and the three first transmission members are rotatably connected to the three driving units.

[0009] According to one embodiment of this application, the cut-off member is provided with a plurality of irregularly shaped through holes at a position away from the position where the cut-off portion is formed and the position where the annular opening is formed. The cross-sectional area of ​​the through holes is smaller than the cross-sectional area of ​​the channel, and the distance between the center of the through holes and the center of the circle formed by the rotation of the cut-off member is smaller than the distance between the axis of the channel and the center of the circle formed by the rotation of the cut-off member.

[0010] According to one embodiment of this application, the cross-sectional area of ​​the intercepting portion is set to be larger than the cross-sectional area of ​​the channel.

[0011] According to one embodiment of this application, the cross-sectional area of ​​the annular opening is set to be the same as the cross-sectional area of ​​the channel.

[0012] According to one embodiment of this application, the location where the intercepting portion is formed is adjacent to the location where the annular opening is formed.

[0013] According to one embodiment of this application, the valve seat is further provided with a movable space outside the channel, the movable space being disposed through the channel and communicating with the channel, so as to allow the shut-off member to move.

[0014] According to one embodiment of this application, the bottom of the valve seat is provided with at least one fixed support leg that can first extend a predetermined length in the vertical direction and then extend a predetermined length in the horizontal direction to form an inverted T-shaped cross-section.

[0015] According to one embodiment of this application, the blind valve further includes a sealing unit, which includes two first annular seals and two second annular seals. The two first annular seals are both made of flexible material and are located in the movable space. Each of the two first annular seals is connected to two broken ends of the channel through which the movable space passes, to abut against at least a portion of the shut-off member. The centers of the two first annular seals are located on the axis of the channel. The cross-sectional area of ​​the inner ring of each first annular seal is equal to the cross-sectional area of ​​the channel. The two second annular seals are both made of flexible material and are connected to different positions of the shut-off member. The centers of the two second annular seals coincide with the center of the throttling portion and the center of the annular opening, respectively. The distance between the center of each second annular seal and the center of the circle formed by the rotation of the shut-off member is equal to the distance between the axis of the channel and the center of the circle formed by the rotation of the shut-off member. The cross-sectional area of ​​the inner ring of each second annular seal is equal to the cross-sectional area of ​​the channel. Attached Figure Description

[0016] Figure 1 A perspective view of the blind valve described in this application is shown.

[0017] Figure 2 A schematic diagram of the blind valve described in this application at one angle is shown.

[0018] Figure 3 A partial structural schematic diagram of the shut-off assembly in the blind valve described in this application is shown.

[0019] Figure 4 A schematic diagram of another state of the blind valve described in this application is shown. Detailed Implementation

[0020] The following description is intended to disclose this application and enable those skilled in the art to implement it. The preferred embodiments described below are merely examples, and other obvious variations will occur to those skilled in the art. The basic principles of this application defined in the following description can be applied to other embodiments, modifications, improvements, equivalents, and other technical solutions that do not depart from the spirit and scope of this application.

[0021] Those skilled in the art should understand that, in the disclosure of this application, the terms "longitudinal," "lateral," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," and "outer," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, the above terms should not be construed as limitations on this application.

[0022] It is understood that the term "a" should be understood as "at least one" or "one or more", that is, in one embodiment, the number of an element can be one, while in another embodiment, the number of the element can be multiple, and the term "a" should not be understood as a limitation on the number.

[0023] refer to Figures 1 to 4 A preferred embodiment of the blind valve according to this application will be described in detail below. The blind valve includes a valve seat 10 and a shut-off assembly 20, wherein the valve seat 10 has an inlet 101, an outlet 102 and a channel 103 disposed between the inlet 101 and the outlet 102 and communicating with the inlet 101 and the outlet 102.

[0024] It is understood that the inlet 101 of the valve seat 10 is used to connect to the pipeline, allowing fluid flowing in the pipeline to enter through the inlet 101, flow through the channel 103, and then flow out through the outlet 102. The shut-off component 20 can close and open the channel 103 when fluid flows through it; that is, the shut-off component 20 can completely close the channel 103 to prevent fluid flowing in the pipeline from flowing from the inlet 101 to the outlet 102, or the shut-off component 20 can open the channel 103 to allow fluid flowing in the pipeline to flow from the inlet 101 to the outlet 102.

[0025] Specifically, the shut-off assembly 20 includes at least three drive units 21, a transmission component 22, and a shut-off component 23. At least three or more drive units 21 are symmetrically arranged on the valve seat 10 with the center of the channel 103 as the center of symmetry, and are located outside the channel 103, so that the center of gravity of at least three or more drive units 21 is located at the center of the channel 103.

[0026] Furthermore, the transmission member 22 is driven by at least three or more drive units 21 to rotate the shut-off member 23 until the shut-off member 23 is at least partially located in the channel 103. The shut-off member 23 also forms a flow-blocking portion 231 with a cross-sectional area not less than that of the channel 103. The distance between the center of the flow-blocking portion 231 and the center of the circle formed by the rotation of the shut-off member 23 is equal to the distance between the axis of the channel 103 and the center of the circle formed by the rotation of the shut-off member 23. Thus, when the flow-blocking portion 231 is completely located in the channel 103, the channel 103 is completely blocked, thereby causing the flow-blocking portion 231 to cut off the channel 103 and close the channel 103.

[0027] Furthermore, the shut-off member 23 also forms an annular opening 2301 with a cross-sectional area not greater than that of the channel 103. The annular opening 2301 is located close to the location of the flow-blocking portion 231. The distance between the center of the annular opening 2301 and the center of the circle formed by the rotation of the shut-off member 23 is equal to the distance between the center of the flow-blocking portion 231 and the center of the circle formed by the rotation of the shut-off member 23. Thus, when the annular opening 2301 is completely located in the channel 103, the annular opening 2301 is connected to the channel 103, so that the channel 103 is opened, thereby allowing fluid to flow in the channel 103.

[0028] Those skilled in the art will understand that, since all the drive units 21 are symmetrically arranged on the valve seat 10 with the center of the channel 103 as the center of symmetry and located on the outside of the channel 103, the total center of gravity of all the drive units 21 is located in the direction of the axis of the channel 103. Furthermore, when the drive unit 21 drives the shut-off member 23 to move, the driving force of each drive unit 21 driving the shut-off member 23 to move is smaller than the driving force required for a single drive unit 21 to drive the shut-off member 23. Consequently, the reaction force received by the drive unit 21 when driving the shut-off member 23 to move is also smaller. That is, the drive unit 21 is less likely to fail in a short period of time, which helps to extend the service life of the drive unit 21 and reduce the number of times the drive unit 21 needs to be inspected and repaired.

[0029] Furthermore, when at least three or more drive units 21 drive the transmission member 22 to rotate the shut-off member 23, the flow-blocking portion 231 of the shut-off member 23 is gradually rotated along with the shut-off member 23 until the channel 103 is completely blocked. At this time, the annular opening 2301 also rotates synchronously with the rotating shut-off member 23 and gradually approaches the channel 103. When the drive unit 21 continues to drive the shut-off member 23 to rotate, the flow-blocking portion 231 of the shut-off member 23 gradually changes from a state of completely blocking the channel 103 to a state of partially blocking the channel 103, until the flow-blocking portion 231 moves away from the channel 103 and is completely located outside the channel 103. At this time, the annular opening 2301 of the shut-off member 23 is completely located inside the channel 103 and remains connected to the channel 103. In this way, the channel 103 can be switched from a closed state to an open state.

[0030] Similarly, when at least three or more of the drive units 21 drive the transmission member 22 to rotate the shut-off member 23, the annular opening 2301 of the shut-off member 23 can gradually deviate from the channel 103 and be located outside the channel 103. At the same time, the flow-blocking part 231 located outside the channel 103 rotates synchronously with the shut-off member 23 and begins to change from a state of partially blocking the channel 103 to a state of completely blocking the channel 103, until the flow-blocking part 231 completely blocks the channel 103. At this time, the annular opening 2301 is located outside the channel 103, so the channel 103 can be switched from an open state to a closed state.

[0031] In this way, when the channel 103 is closed, the fluid entering the inlet 101 will be blocked by the intercepting part 231 and will not be able to flow to the outlet 102 during its flow to the outlet 102; while when the channel 103 is open, the fluid entering the inlet 101 will not be blocked and will be able to flow through the channel 103 and the annular opening 2301 toward the outlet 102.

[0032] Preferably, each of the drive units 21 is connected to the valve seat 10 to increase drive stability. It is understood that each of the drive units 21 is implemented as a drive motor.

[0033] Preferably, the transmission component 22 includes the same number of first transmission members 221 and a second transmission member 222 as the drive unit 21, wherein one first transmission member 221 is synchronously rotatably connected to one of the drive units 21, and each first transmission member 221 is also rotatably connected to the valve seat 10. The shut-off member 23 is connected to one of the first transmission members 221. The second transmission member 222 is rollably engaged with the other end of each first transmission member 221 in a manner surrounding the outside of the channel 103. Thus, when the drive unit 21 drives the first transmission member 221 to rotate, the second transmission member 222 is driven to rotate as well. In this way, the first transmission member 221 connected to the shut-off member 23 can also be driven by the other first transmission members 221 to roll and act, thereby reducing the driving pressure of the drive unit 21 that drives the first transmission member 221 connected to the shut-off member 23 to rotate.

[0034] It should be further noted that as the number of drive units 21 increases, the number of first transmission members 221 also increases, making it easier for the second transmission member 222 to be driven and rolled. In other words, the heavier cut-off member 23 can be driven by the increased number of drive units 21 to complete the operation of rotating the transmission member 22 by the predetermined angle, thereby making it easier for the channel 103 to be closed and opened.

[0035] Specifically, in one example, such as Figure 1 , Figure 2 and Figure 4 As shown, the number of drive units 21 is set to three, and the three drive units 21 are distributed evenly and at intervals on the outer side of the channel 103, and the lines connecting each pair of the three drive units 21 form an equilateral triangle. Correspondingly, the number of first transmission members 221 is also set to three, and the three first transmission members 221 are rotatably connected to the three drive units 21 synchronously.

[0036] Preferably, the first transmission member 221 connected to the shut-off member 23 is connected to the highest of the three drive units 21. It is understood that, compared to the drive units 21 at other positions that overcome gravity to drive the shut-off member 23, the drive unit 21 at the highest position overcomes less gravity, thus making it easier to drive the shut-off member 23.

[0037] Preferably, each of the first transmission members 221 is configured as a sprocket with a rotating shaft, wherein the drive unit 21 is connected to the rotating shaft of the sprocket, and the second transmission member 222 is implemented to include a chain that meshes with the sprocket.

[0038] Preferably, the shut-off member 23 is provided with a plurality of irregularly shaped through holes 2302 at a position away from the position where the intercepting part 231 is formed and the position where the annular opening 2301 is formed, so as to reduce the overall weight of the shut-off member 23, thereby further reducing the driving pressure of the driving unit 21 to drive the shut-off member 23 to rotate. In addition, the cross-sectional area of ​​the through hole 2302 is smaller than the cross-sectional area of ​​the channel 103, and the distance between the center of the through hole 2302 and the center of the circle formed by the rotation of the shut-off member 23 is smaller than the distance between the axis of the channel 103 and the center of the circle formed by the rotation of the shut-off member 23.

[0039] It is worth mentioning that some of the through holes 2302 are located between the intercepting part 231 and the annular opening 2301, so that when the channel 103 switches from the open state to the closed state or from the closed state to the open state, the channel 103 is briefly in the open state through the through holes 2302.

[0040] Preferably, the cross-sectional area of ​​the intercepting part 231 is set to be larger than the cross-sectional area of ​​the channel 103, so that the predetermined angle by which the driving unit 21 drives the intercepting member 23 to rotate as a whole is reduced, thereby making the channel 103 close more quickly.

[0041] Preferably, the cross-sectional area of ​​the annular opening 2301 is set to be the same as the cross-sectional area of ​​the channel 103, so that when the annular opening 2301 is completely located in the channel 103, the channel 103 is fully opened to allow fluid flow.

[0042] In a preferred embodiment, specifically as follows: Figure 3 As shown, the intercepting part 231 is positioned adjacent to the annular opening 2301, thereby enabling the channel 103 to be closed and opened more quickly to facilitate fluid flow.

[0043] Preferably, the valve seat 10 is further provided with a movable space 104 outside the channel 103. The movable space 104 is disposed through and communicates with the channel 103 to allow the shut-off member 23 to move. That is, the shut-off member 23 is driven by the drive units 21 to move in the movable space 104 so that the channel 103 is completely closed by the throttling part 231 or opened by communicating with the annular opening 2301.

[0044] Preferably, the bottom of the valve seat 10 is provided with at least one fixed support leg 11 that can first extend a predetermined length in the vertical direction and then extend a predetermined length in the horizontal direction to form an inverted T-shaped cross-section, for engaging with an external device, thereby fixing the valve seat 10.

[0045] Furthermore, the blind valve also includes a sealing unit 30. Preferably, the sealing unit 30 includes two first annular seals 31 and two second annular seals 32. The two first annular seals 31 are made of flexible material and are located in the movable space 104. The two first annular seals 31 are respectively connected to the two broken ends of the channel 103 through which the movable space 104 passes, so as to abut at least a portion of the cut-off member 23. The centers of the two first annular seals 31 are located on the axis of the channel 103. In addition, the cross-sectional area of ​​the inner ring of each first annular seal 31 is equal to the cross-sectional area of ​​the channel 103.

[0046] Both second annular seals 32 are made of flexible material and are connected to different positions of the shut-off member 23. The centers of the two second annular seals 32 coincide with the center of the shut-off portion 231 and the center of the annular opening 2301, respectively. The distance between the center of each second annular seal 32 and the center of the circle formed by the rotation of the shut-off member 23 is equal to the distance between the axis of the channel 103 and the center of the circle formed by the rotation of the shut-off member 23. Furthermore, the cross-sectional area of ​​the inner ring of each second annular seal 32 is equal to the cross-sectional area of ​​the channel 103.

[0047] It is understood that when the shut-off member 23 moves in the active space 104, the two first annular seals 31 always abut against at least a portion of the shut-off member 23. For example, when the flow-blocking portion 231 of the shut-off member 23 is completely located in front of the channel 103, that is, if at least a portion of the inner ring cross-sectional area of ​​only one second annular seal 32 that coincides with the center of the flow-blocking portion 231 coincides with the cross-sectional area of ​​the channel 103, the two first annular seals 31 completely abut against the opposite sides of the shut-off member 23 to prevent the channel 103 from continuing to communicate with the active space 104; if at least a portion of the inner ring cross-sectional area of ​​only one second annular seal 32 that coincides with the center of the flow-blocking portion 231 coincides with the cross-sectional area of ​​the channel 103... When the cross-sectional area of ​​the inner ring of the second annular seal 32, which overlaps with the center of the annular opening 2301, also overlaps with the cross-sectional area of ​​the channel 103, at least a portion of the two first annular seals 31 directly abuts against the cut-off member 23, and at least another portion of the two first annular seals 31 remains abutting against each other through the annular opening 2301. At this time, the annular opening 2301 is divided into two parts by the two abutting first annular seals 31, wherein a portion of the annular opening 2301 is located in the channel 103, and the other portion of the annular opening 2301 is located outside the channel 103, thereby preventing the channel 103 from communicating with the active space 104 through the annular opening 2301.

[0048] When the flow-blocking portion 231 of the cut-off member 23 is completely located in the channel 103, one of the two first annular seals 31 directly abuts against the cut-off member 23, and the other of the two first annular seals 31 completely abuts against the second annular seal 32 that is aligned with the center of the flow-blocking portion 231 in such a way that their cross-sectional areas overlap, so as to maintain the sealing state of the channel 103.

[0049] When the annular opening 2301 of the shut-off member 23 is completely located in the channel 103, one of the two first annular seals 31 directly abuts against the shut-off member 23, and the other of the two first annular seals 31 completely abuts against the second annular seal 32 that is aligned with the center of the annular opening 2301 in such a way that their cross-sectional areas overlap, so as to maintain the sealing state of the channel 103.

[0050] It is also worth mentioning that when the channel 103 is briefly in an open state through the through hole 2302, that is, when the cross-sectional area of ​​part of the through hole 2302 only partially overlaps with the cross-sectional area of ​​the channel 103, at least part of the two first annular seals 31 are kept in contact with each other through the through hole 2302 to maintain the sealing state of the channel 103.

[0051] Thus, the blind valve maintains the sealing state of the channel 103 by means of the sealing unit 30 to reduce fluid leakage.

[0052] Preferably, both the first annular seal 31 and the second annular seal 32 are configured as rubber rings.

[0053] Those skilled in the art should understand that the embodiments of this application described above and shown in the accompanying drawings are merely examples and do not limit the scope of this application. The advantages of this application have been fully and effectively implemented. The functional and structural principles of this application have been demonstrated and explained in the embodiments, and any variations or modifications can be made to the implementation of this application without departing from the stated principles.

Claims

1. A blind valve, characterized in that, The blind valve includes: A valve seat having an inlet, an outlet, and a channel disposed between and communicating with the inlet and the outlet; A shut-off assembly includes at least three drive units, a transmission component, and a shut-off member. The at least three drive units are symmetrically arranged on the valve seat with the center of the channel as their center of symmetry, and are located outside the channel, so that the center of gravity of the at least three drive units is located at the center of the channel. The transmission component, driven by the at least three drive units, rotates the shut-off member until the shut-off member is at least partially located within the channel. The shut-off member also forms a flow-blocking section with a cross-sectional area not less than the cross-sectional area of ​​the channel. The distance between the center of the cut-off section and the center of the circle formed by the rotation of the cut-off member is equal to the distance between the axis of the channel and the center of the circle formed by the rotation of the cut-off member. Thus, when the cut-off section is completely located in the channel, the cut-off section closes the channel. The cut-off member also forms an annular opening with a cross-sectional area not greater than the cross-sectional area of ​​the channel. The distance between the center of the annular opening and the center of the circle formed by the rotation of the cut-off member is equal to the distance between the center of the cut-off section and the center of the circle formed by the rotation of the cut-off member. Thus, when the annular opening is completely located in the channel, the annular opening communicates with the channel to open the channel.

2. The blind valve according to claim 1, characterized in that, The transmission component includes the same number of first transmission members and second transmission members as the drive unit, wherein one of the first transmission members is synchronously rotatably connected to one of the drive units, and each of the first transmission members is also rotatably connected to the valve seat, the shut-off member is connected to one of the first transmission members, and the second transmission member is rollably engaged with the other end of each of the first transmission members in a manner surrounding the outside of the channel.

3. The blind valve according to claim 2, characterized in that, The number of drive units is set to three, and the three drive units are distributed evenly and at intervals on the outside of the channel. The lines connecting the three drive units in pairs form an equilateral triangle. The number of first transmission members is also set to three, and the three first transmission members are rotatably connected to the three drive units.

4. The blind valve according to claim 2, characterized in that, The cut-off member has multiple irregularly shaped through holes at a position away from the position where the cut-off part is formed and the position where the annular opening is formed. The cross-sectional area of ​​the through holes is smaller than the cross-sectional area of ​​the channel. The distance between the center of the through hole and the center of the circle formed by the rotation of the cut-off member is smaller than the distance between the axis of the channel and the center of the circle formed by the rotation of the cut-off member.

5. The blind valve according to claim 4, characterized in that, The cross-sectional area of ​​the intercepting section is set to be larger than the cross-sectional area of ​​the channel.

6. The blind valve according to claim 5, characterized in that, The cross-sectional area of ​​the annular opening is set to be the same as the cross-sectional area of ​​the channel.

7. The blind valve according to claim 6, characterized in that, The location where the intercepting section is formed is adjacent to the location where the annular opening is formed.

8. The blind valve according to claim 7, characterized in that, The valve seat also has a movable space outside the channel, which is provided through and communicates with the channel to allow the shut-off element to move.

9. The blind valve according to claim 8, characterized in that, The bottom of the valve seat is provided with at least one fixed support leg that can first extend a predetermined length in the vertical direction and then extend a predetermined length in the horizontal direction to form an inverted T-shaped cross-section.

10. The blind valve according to claim 8, characterized in that, The blind valve further includes a sealing unit comprising two first annular seals and two second annular seals. Both first annular seals are made of flexible material and are located within the movable space. Each first annular seal is connected to one of the two broken ends of the channel through which the movable space passes, abutting against at least a portion of the shut-off member. The centers of both first annular seals are located on the axis of the channel. The inner cross-sectional area of ​​each first annular seal is equal to the cross-sectional area of ​​the channel. Both second annular seals are made of flexible material and are connected to different positions on the shut-off member. The centers of both second annular seals coincide with the center of the throttling portion and the center of the annular opening, respectively. The distance between the center of each second annular seal and the center of the circle formed by the rotation of the shut-off member is equal to the distance between the axis of the channel and the center of the circle formed by the rotation of the shut-off member. The inner cross-sectional area of ​​each second annular seal is equal to the cross-sectional area of ​​the channel.

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