Valve disc assembly and parallel type double-gate-disc gate valve adopting same

Abstract

The utility model relates to a valve disc assembly and a parallel type double-gate-disc gate valve adopting the valve disc assembly, and belongs to the technical field of valves. Comprising a pair of valve discs of the same structure. The valve rod structure is used for driving the valve disc to move in the valve body so as to control the opening and closing of the flow channel; the valve disc is provided with a sealing face, and the sealing face comprises a central area used for being in contact with a medium; the peripheral sealing area surrounds the central area and is used for being matched with a valve seat; and a variable sealing unit is arranged in the peripheral sealing area. When the valve rod structure drives the pair of valve discs to move upwards or downwards in the valve body, due to the fact that the deformable walls of the variable sealing units do not protrude out of the surfaces of the valve discs, contact and friction do not exist between the variable sealing units and the valve seats, and the problem that in the prior art, sealing rings are abraded due to sliding friction is solved.

Description

Technical Field

[0001] The utility model belongs to the technical field of valves, and in particular relates to a valve disc assembly and a parallel double-disc gate valve using the assembly. Background Art

[0002] The parallel double-disc gate valve is an important type of gate valve. Its opening and closing parts are composed of two separate, parallel valve discs (or gates). Driven by the valve stem, the valve discs move up and down perpendicular to the direction of the medium flow, thereby connecting or blocking the pipeline medium.

[0003] To ensure a reliable seal when the valve is closed, a common practice is to create a sealing groove on the sealing surface of the valve disc (i.e., the end surface that contacts the valve seat) and insert an elastic sealing ring into the groove. This sealing ring is typically made of an elastomeric material such as nitrile rubber or fluororubber. Relying on its inherent elastic deformation, it generates sufficient pre-compressive stress when in contact with the valve seat, thereby filling any microscopic irregularities on the metal surface and effectively isolating the medium and preventing leakage.

[0004] However, this sealing structure, which relies on the pre-compression of the elastic sealing ring, has an inherent flaw that is difficult to overcome. To achieve an effective seal, the elastic sealing ring must slightly protrude from the sealing surface of the valve disc when in its free state. Because of this "protrusion," the protruding portion of the sealing ring inevitably slides against the sealing surface of the valve seat over long distances during the entire lifting and lowering process of the valve opening or closing. This causes rapid wear of the elastic sealing ring. Each time the valve is opened and closed, the protruding portion of the sealing ring is continuously worn away. As the number of openings and closings increases, wear accumulates, the effective height of the sealing ring gradually decreases, and its pre-compression also decreases. This ultimately leads to a sharp decline in sealing performance, until it completely fails and causes internal leakage in the valve. Utility Model Content

[0005] In order to solve the above-mentioned problems in the prior art, the utility model provides a valve disc assembly and a parallel double-disc gate valve using the assembly.

[0006] In order to achieve the above purpose, the technical solution adopted by the utility model is:

[0007] A valve disc assembly is provided, comprising:

[0008] A pair of valve discs with identical structure;

[0009] A valve stem structure, used to drive the valve disc to move in the valve body to control the opening and closing of the flow channel;

[0010] The valve disc is provided with a sealing surface, and the sealing surface comprises:

[0011] A central area for contact with the medium;

[0012] a peripheral sealing area surrounding the central area and adapted to cooperate with the valve seat;

[0013] Wherein, a variable sealing unit is provided in the peripheral sealing area;

[0014] Wherein, at least during the movement of the valve stem structure, a deformable wall of the variable sealing unit is filled with a sealing medium and forms a sealing contact with the valve seat of the valve body.

[0015] Preferably, the variable sealing unit includes:

[0016] an annular cavity, which is arranged in the peripheral sealing area and has the deformable wall;

[0017] a storage cavity, for accommodating the sealing medium;

[0018] a medium channel, used for connecting the annular cavity and the storage cavity;

[0019] The valve stem structure causes the sealing medium of the storage cavity to flow into the annular cavity via the medium channel, so as to push the deformable wall to deform and expand.

[0020] Preferably, the annular cavity comprises at least two coaxially arranged independent sealed cavities;

[0021] The deformable walls corresponding to the at least two independent sealed cavities are configured to generate different deformation amounts so as to form a sealing step on the cross section of the peripheral sealing area.

[0022] Preferably, the end surface of the valve seat facing the valve disc has:

[0023] annular groove;

[0024] The position and number of the annular grooves are adapted to the annular cavity;

[0025] Wherein, at least a portion of the deformable wall of the independent sealed cavity can be embedded in the corresponding annular groove.

[0026] Preferably, the valve stem structure comprises:

[0027] a pressurizing assembly, the pressurizing assembly being used to cooperate with the storage cavity;

[0028] The pressurizing assembly applies pressure to the sealing medium in the storage cavity in response to the axial movement of the valve stem structure.

[0029] Preferably, the pressurizing component comprises:

[0030] an abutting block, wherein the abutting block has an arc-shaped abutting surface;

[0031] Wherein, the abutment surface is configured to form an abutment with the storage cavity during the axial movement of the valve stem structure.

[0032] Preferably, the storage cavity is arranged at the center of the end surfaces of the valve disc facing each other, and has:

[0033] an elastic wall surface, wherein the elastic wall surface is protruded toward the valve stem structure in an initial state;

[0034] Wherein, the elastic wall surface is configured to form abutment with the abutment surface of the abutment block.

[0035] Preferably, the valve stem structure comprises:

[0036] a first wedge-shaped member disposed between the pair of valve discs;

[0037] wherein the axial movement of the valve stem structure causes the first wedge-shaped member to come into sliding contact with the valve disc, and causes the valve disc to move toward the valve seat;

[0038] Wherein, the abutment block is arranged at the center position of the wedge-shaped member.

[0039] Preferably, the end surfaces of the valve disc facing each other have:

[0040] a second wedge-shaped member;

[0041] The second wedge surface of the second wedge-shaped member is in slidable contact with the first wedge surface of the first wedge-shaped member.

[0042] The utility model also provides a parallel double-disc gate valve using the assembly, comprising at least:

[0043] A valve disc assembly as described in any of the above technical solutions.

[0044] The utility model provides a valve disc assembly and a parallel double-disc gate valve using the assembly. The beneficial effects of the utility model are embodied in:

[0045] When the valve stem structure drives a pair of valve discs to move upward or downward in the valve body, since the deformable wall of the variable sealing unit does not protrude from the surface of the valve disc, there is no contact and friction between it and the valve seat, thereby solving the problem of wear of the sealing ring due to sliding friction in the prior art.

[0046] When the valve stem reaches the end of its travel or in the final stage of its movement, it is squeezed by the variable sealing unit. As a result, the sealing medium in the variable sealing unit causes the deformable wall to elastically deform and expand outward, pressing tightly against the surface of the valve seat to form a tight seal. BRIEF DESCRIPTION OF THE DRAWINGS

[0047] Figure 1 This is a cross-sectional view of the valve disc assembly proposed in the present utility model;

[0048] Figure 2 for Figure 1 A local enlarged schematic diagram at point A;

[0049] Figure 3 for Figure 1 A local enlarged schematic diagram at point B;

[0050] Figure 4 This is a schematic structural diagram of a pressurizing assembly in one structural form of the valve disc assembly proposed in the present invention;

[0051] Figure 5 This is a schematic diagram of the cooperation between the pressurizing component and the elastic wall surface in one structural form of the valve disc assembly proposed in the present invention;

[0052] Figure 6 This is a schematic structural diagram of the valve disc in the valve disc assembly proposed by the present invention;

[0053] Figure 7 This is a structural schematic diagram of the first wedge-shaped member and the second wedge-shaped member in the valve disc assembly proposed by the present invention;

[0054] Figure 8 This is a schematic structural diagram of the second wedge-shaped member in the valve disc assembly proposed in the present invention.

[0055] Description of reference numerals:

[0056] 1. Valve disc; 101. Sealing surface; 1011. Central area; 1012. Peripheral sealing area; 2. Valve stem structure; 201. Pressurizing assembly; 3. Variable sealing unit; 301. Deformable wall; 302. Annular cavity; 303. Storage cavity; 3031. Elastic wall; 304. Medium channel; 4. Valve seat; 401. Annular groove; 501. First wedge; 5011. First wedge surface; 502. Second wedge; 5021. Second wedge surface; 6. Guide groove. DETAILED DESCRIPTION

[0057] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the embodiments described are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0058] See also Figures 1-8As shown, the specific embodiments provided by the present invention are as follows:

[0059] like Figures 1 to 3 As shown, the embodiment of the utility model provides a valve disc assembly, which is particularly suitable for valves requiring high reliability sealing, such as parallel double-disc gate valves.

[0060] The valve disc assembly includes a pair of valve discs 1 with identical structures and a valve stem structure 2 .

[0061] The valve stem structure 2 is the driving portion of the valve disc assembly and is connected to an external drive device (such as a handwheel or electric actuator). Operating the external drive device causes the valve stem structure 2 to produce axial reciprocating motion (i.e., up and down movement as shown), thereby driving the pair of valve discs 1 to move synchronously within the valve body's inner cavity. This controls the opening and closing of the flow channel within the valve body, thereby achieving on-off control of the pipeline medium.

[0062] Each valve disc 1 has a sealing surface 101 for achieving sealing. The sealing surface 101 is the end surface of the valve disc 1 facing the medium in the valve body and ultimately in contact with the valve seat 4. Specifically, the sealing surface 101 is divided into two areas: a central area 1011 and a peripheral sealing area 1012.

[0063] The central area 1011 is located inside the sealing surface 101. When the valve is open, the central area 1011 is operated to leave the medium flow channel and allow the medium to pass through. When the valve is closed, the central area 1011 is operated to be located in the medium flow channel and prevent the medium from passing through.

[0064] The peripheral sealing area 1012 surrounds the periphery of the central area 1011. When the valve is closed, the peripheral sealing area 1012 is the area where the valve disc 1 and the valve seat 4 on the valve body are mechanically matched to form a basic seal.

[0065] On the basis of the above, a variable sealing unit 3 is provided in the peripheral sealing area 1012 of each valve disc 1 .

[0066] Specifically, the variable sealing unit 3 has a deformable wall 301 on its side facing the valve seat 4. This deformable wall 301 can be made of a composite material with a certain degree of elasticity. In the initial state, the surface of the deformable wall 301 can be flush with the rest of the peripheral sealing area 1012, or slightly recessed, but not protruding.

[0067] When the valve stem structure 2 drives a pair of valve discs 1 to move upward or downward in the valve body, since the deformable wall 301 of the variable sealing unit 3 does not protrude from the surface of the valve disc 1, there is no contact and friction between it and the valve seat 4, thereby solving the problem of wear of the sealing ring due to sliding friction in the prior art.

[0068] When the valve stem structure 2 drives the valve disc 1 to the fully closed position, the peripheral sealing area 1012 of the valve disc 1 first contacts the valve seat 4, forming a primary seal. Then, at the end of its travel, or in the final stage of its movement, the valve stem structure 2 is squeezed by the variable sealing unit 3. This causes the sealing medium within the variable sealing unit 3 to elastically deform and expand the deformable wall 301 outward, pressing it tightly against the surface of the valve seat 4, forming a tight secondary seal.

[0069] This seal formed by the deformable wall 301 being deformed under pressure can compensate for any processing errors, scratches or wear caused by long-term use that may exist on the main sealing surface 101, thereby improving the sealing performance of the valve.

[0070] When the valve needs to be opened again, the valve stem structure 2 begins to move in the opposite direction, and the pressure of the sealing medium is released, causing the deformable wall 301 to return to its original shape due to its own elasticity or the backflow of the medium, and the compression state with the valve seat 4 is released. Subsequently, the valve disc 1 begins to move up and down, and the whole process also does not have sliding friction.

[0071] like Figures 2 to 6 As shown, in this embodiment, the variable sealing unit 3 includes an annular cavity 302, a storage cavity 303, and a medium channel 304 connecting the two.

[0072] Specifically, the annular cavity 302 is the final execution portion of the variable sealing unit 3. Specifically, the annular cavity 302 is an annular groove machined within the peripheral sealing area 1012 of the valve disc 1. This groove is entirely closed, but its wall facing the valve seat 4 is an elastic wall surface, namely the deformable wall 301.

[0073] In order to provide the annular cavity 302 with a sealing medium for expansion, a storage cavity 303 is provided on the valve disc 1. The storage cavity 303 can be understood as a sealing medium pre-filled with a sufficient amount of good fluidity and high-pressure stability, such as high-pressure sealing grease or hydraulic oil.

[0074] To connect the two cavities, one or more fine media channels 304 are provided inside the valve disc 1. One end of each media channel 304 communicates with the interior of the storage chamber 303, while the other end opens onto the inner wall of the annular chamber 302. This channel 304 forms a path for the sealing medium to flow from the storage end to the actuating end.

[0075] When the valve stem structure 2 drives the valve disc 1 to the fully closed position and forms initial mechanical contact with the valve seat 4, the continued movement of the valve stem structure 2 applies a squeezing force to the storage chamber 303. This squeezing force increases the pressure of the sealing medium in the storage chamber 303. The high-pressure sealing medium is pressed into the annular chamber 302 through the medium passage 304.

[0076] The influx of sealing medium fills the entire annular cavity 302, thereby pushing the deformable wall 301 outside thereof to deform and expand outward. This expansion action causes the outer surface of the deformable wall 301 to be tightly pressed against the surface of the valve seat 4, forming a seal.

[0077] Preferably, the single annular cavity 302 originally provided in the peripheral sealing area 1012 of the valve disc 1 is further constructed into at least two coaxially arranged independent sealing cavities.

[0078] Specifically, two or more parallel, non-connected annular grooves can be machined radially outward within the peripheral sealing area 1012. Each independent annular groove forms an independent sealed cavity, and each independent sealed cavity is connected to the storage cavity 303 via its own medium channel 304 (or a branch channel). Similarly, each independent sealed cavity has a deformable wall 301 on the side facing the valve seat 4.

[0079] Furthermore, at least two deformable walls 301 have different wall thicknesses. For example, an inner independent sealed cavity and an outer independent sealed cavity may be provided. The deformable wall 301 of the inner independent sealed cavity may be thinner and more flexible than the deformable wall 301 of the outer independent sealed cavity.

[0080] In this way, when the valve is closed and the sealing medium from the storage chamber 303 is injected into the two independent sealing chambers at the same time through the medium channel 304, due to the difference in structural strength, the inner deformable wall 301 with a thinner wall thickness will produce a larger elastic deformation and expand more toward the valve seat 4; while the outer deformable wall 301 with a thicker wall thickness will produce a relatively small deformation and expand less.

[0081] This gradient expansion forms a stepped sealing pressure distribution on the contact surface between the valve disc 1 and the valve seat 4 , namely the sealing step of this embodiment.

[0082] In general, this multi-stage, progressive sealing approach is equivalent to setting up multiple lines of defense. Even if one sealing line fails to seal completely due to the presence of the deformable wall 301, the other independent sealing line behind (or before) it will still function perfectly, ensuring the overall tightness of the valve and greatly improving the redundancy and ultimate reliability of the seal.

[0083] In this embodiment, one or more annular grooves 401 adapted to the variable sealing unit 3 are correspondingly processed on the end surface of the valve seat 4 facing the valve disc 1 (ie, the sealing surface 401 of the valve seat 4 ).

[0084] Adaptation here means that if there are two coaxial independent sealing cavities on the valve disc 1, then there are corresponding two ring grooves 401 on the valve seat 4. The radial position, width and depth of each ring groove 401 accommodate the shape of the corresponding deformable wall 301 after expansion.

[0085] Based on this structure, under the pressure of the internal sealing medium, the deformable wall 301 of each independent sealing cavity no longer just presses against a plane, but expands outward and embeds into the inside of the annular groove 401 on the valve seat 4, forming a complementary concave and convex fitting relationship.

[0086] Based on this, if the medium wants to leak, its path no longer follows a straight contact line. Instead, it must follow a curved path along the outer surface of the deformable wall 301 and the inner surface of the annular groove 401 (including the groove bottom and two side walls). This effectively prevents leakage and is particularly effective for gas sealing.

[0087] In this embodiment, the valve stem structure 2 includes a pressurizing assembly 201. Of course, this pressurizing assembly 201 is not active throughout the entire movement of the valve stem structure 2. It is configured to be activated only during the very short stroke immediately before the valve is fully closed. During the valve's opening or most of its closing stroke, there is no force acting between the pressurizing assembly 201 and the storage chamber 303; it simply moves silently with the valve stem.

[0088] Specifically, when the valve stem structure 2 drives the valve disc 1 to move to the closed position, the final stage of its axial movement triggers the pressurizing component 201. The pressurizing component 201 then responds to this stroke signal and applies a mechanical pressure to the storage chamber 303 that cooperates with it.

[0089] For example, the mechanical pressure can be a direct squeezing force, a pushing force or other forms of force, which directly results in an increase in the pressure of the sealing medium in the storage cavity 303. The medium is then pumped into the medium channel 304 and eventually reaches the annular cavity 302, completing the final active sealing action.

[0090] In a specific embodiment, the pressurizing component 201 is an abutment block which is arranged at the end of the valve stem structure 2 or on other components which move axially synchronously with the valve stem structure 2 and moves synchronously with the rise and fall of the valve stem.

[0091] The side of the abutment block facing the storage cavity 303 is processed into a smooth and arc-shaped abutment surface. Correspondingly, the storage cavity 303 also has a deformable elastic wall 3031. The elastic wall 3031 faces the movement path of the abutment block on the valve stem structure 2.

[0092] Of course, in a specific embodiment, the radial width of the pressurizing assembly 201 (specifically the aforementioned abutting block) is substantially equal to or slightly larger than the initial distance between the pair of valve discs 1 .

[0093] In this structural form, when the valve stem structure 2 drives the abutment block to move downward, after it contacts the elastic wall 3031 of the storage chamber 303, it will only produce a relatively small compression stroke and deformation on the elastic wall 3031, so as to produce a moderate sealing pressurization and form a reliable contact force, which is suitable for low-pressure environments with low sealing requirements.

[0094] In another embodiment, the abutment block maintains its maximum radial width while exhibiting a spindle-shaped or olive-shaped profile that is wide in the middle and narrow at both ends. Accordingly, the initial protrusion of the elastic wall 3031 of the storage cavity 303 can also be configured to be greater, that is, more sealing medium is pre-filled in the storage cavity 303.

[0095] When the valve stem structure 2 drives the spindle-shaped abutment block downward, a two-stage pressurization process occurs:

[0096] First, the narrow lower end of the abutting block first passes through the elastic wall surface 3031 . Due to its small width, it is not sufficient to effectively contact and squeeze the protruding elastic wall surface 3031 .

[0097] Secondly, when the wide middle portion of the abutment block moves into contact with the elastic wall 3031, it compresses it. This compression stroke causes the volume of the storage chamber 303 to decrease to a relatively large extent, thereby pumping the sealing medium into the annular chamber 302, thus meeting the high-pressure sealing requirements in a relatively high-sealing environment.

[0098] Furthermore, in another embodiment, the amount of the sealing medium can be controlled to a state where the liquid circuit (including the storage chamber 303, the medium channel 304, and the annular chamber 302) is completely filled with the incompressible sealing medium, with virtually no air or other gaps remaining.

[0099] In this state, a hydraulic amplification effect occurs. At this time, even if the elastic wall 3031 of the storage cavity 303 undergoes only a very small degree of concave deformation, this tiny volume change will be transmitted to the annular cavity 302, causing the deformable wall 301 outside thereof to expand outward to a greater extent.

[0100] It should be emphasized that the aforementioned embodiments are designed to ensure that the operation of the variable sealing unit 3 does not affect the mechanical primary sealing effect when the valve disc 1 assembly is radially stretched apart by the first wedge 501 and the second wedge 502. This ensures that the two sealing mechanisms can work together while being structurally independent and independent of each other, thereby achieving overall optimal sealing performance.

[0101] In addition, during the valve opening or most of the closing stroke, the abutment block on the valve stem structure 2 moves up and down with the valve stem, but maintains a preset distance between it and the elastic wall 3031 of the storage cavity 303, and the two do not come into contact.

[0102] When the valve stem structure 2 reaches the end of its closing stroke, its continued axial movement causes the abutment block to eventually abut against the elastic wall 3031 of the storage chamber 303. The curved abutment surface of the abutment block acts like a gentle cam, continuously applying pressure to the elastic wall 3031, pushing it toward the interior of the storage chamber 303. This pressure compresses and reduces the internal volume of the storage chamber 303. This pressure then pumps the sealing medium through the medium passage 304 and into the annular cavity 302 on the sealing surface 101 of the valve disc 1, thereby driving the deformable wall 301 to expand and ultimately achieving active sealing.

[0103] like Figures 7 and 8 As shown, in this embodiment, the valve stem structure 2 includes a first wedge-shaped member 501 positioned between a pair of valve discs 1. The upper portion of the first wedge-shaped member 501 is connected to the end of the valve stem structure 2. It has wedge blocks on both sides forming first wedge surfaces 5011, and the aforementioned abutment block is located in its center.

[0104] Correspondingly, each valve disc 1 is equipped with a second wedge 502 on its facing end faces. Furthermore, a guide groove 6 extending axially along the valve stem is defined at the center of the second wedge 502. The abutment block is located within and can slide along the guide groove 6. The axial length of the guide groove 6 is greater than that of the abutment block, thus creating a predetermined free travel.

[0105] Therefore, when the valve stem structure 2 moves downward, for most of the stroke, the entire valve disc assembly (including the valve stem structure 2, the first wedge 501, and the two valve discs 1) moves downward synchronously as a rigid unit. At this point, the abutment block on the first wedge 501 is located above the guide groove 6, with a free travel gap between it and the bottom of the guide groove 6.

[0106] When the lower edges of the two valve discs 1 touch the preset limit steps in the valve body, the axial movement of the two valve discs 1 stops. At this time, they are located in the middle of the valve flow channel, completing the physical blockage of the medium flow channel. Although the valve disc 1 has stopped, the valve stem structure 2 can continue to independently make the final downward displacement under the action of the external driving force. The distance of this displacement is provided by the free stroke of the guide groove 6. At this time, the first wedge 501 continues to move downward with the valve stem structure 2, and the first wedge surface 5011 thereon slides downward along the second wedge surface 5021 on the stationary valve disc 1. Due to the decomposition of the inclined surface force, this downward force is converted into a lateral thrust, which radially stretches the two valve discs 1 to both sides, so that the outer sealing surface 101 is tightly pressed against the valve seat 4 on both sides to form a main seal.

[0107] At the same time, as the first wedge 501 moves downward, the abutment block in its center also moves downward synchronously and begins to squeeze the elastic wall 3031 of the storage cavity 303 located in the center of the valve disc 1, thereby activating the active hydraulic sealing system and forming an auxiliary seal.

[0108] The utility model also provides a parallel double-disc gate valve using the assembly, including the valve disc assembly in any of the above embodiments, which will not be described in detail here.

[0109] Although the embodiments of the present invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and variations may be made to these embodiments without departing from the principles and spirit of the present invention, and the scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A valve disc assembly, characterized in that: include: A pair of valve discs with identical structure; A valve stem structure, used to drive the valve disc to move in the valve body to control the opening and closing of the flow channel; The valve disc is provided with a sealing surface, and the sealing surface comprises: A central area for contact with the medium; a peripheral sealing area surrounding the central area and adapted to cooperate with the valve seat; Wherein, a variable sealing unit is provided in the peripheral sealing area; Wherein, at least during the movement of the valve stem structure, a deformable wall of the variable sealing unit is filled with a sealing medium and forms a sealing contact with the valve seat of the valve body.

2. The valve disc assembly according to claim 1, characterized in that The variable sealing unit comprises: an annular cavity, which is arranged in the peripheral sealing area and has the deformable wall; a storage cavity, for accommodating the sealing medium; a medium channel, used for connecting the annular cavity and the storage cavity; The valve stem structure causes the sealing medium of the storage cavity to flow into the annular cavity via the medium channel, so as to push the deformable wall to deform and expand.

3. The valve disc assembly according to claim 2, characterized in that The annular cavity includes at least two coaxially arranged independent sealing cavities; The deformable walls corresponding to the at least two independent sealed cavities are configured to generate different deformation amounts so as to form a sealing step on the cross section of the peripheral sealing area.

4. The valve disc assembly according to claim 3, characterized in that The end surface of the valve seat facing the valve disc has: annular groove; The position and number of the annular grooves are adapted to the annular cavity; Wherein, at least a portion of the deformable wall of the independent sealed cavity can be embedded in the corresponding annular groove.

5. The valve disc assembly according to claim 2, wherein: The valve stem structure comprises: a pressurizing assembly, the pressurizing assembly being used to cooperate with the storage cavity; The pressurizing assembly applies pressure to the sealing medium in the storage cavity in response to the axial movement of the valve stem structure.

6. The valve disc assembly according to claim 5, characterized in that The pressurizing assembly comprises: an abutting block, wherein the abutting block has an arc-shaped abutting surface; Wherein, the abutment surface is configured to form an abutment with the storage cavity during the axial movement of the valve stem structure.

7. The valve disc assembly according to claim 6, characterized in that The storage cavity is arranged at the center of the end surfaces of the valve disc facing each other and has: an elastic wall surface, wherein the elastic wall surface is protruded toward the valve stem structure in an initial state; Wherein, the elastic wall surface is configured to form abutment with the abutment surface of the abutment block.

8. The valve disc assembly according to claim 7, wherein: The valve stem structure comprises: a first wedge-shaped member disposed between the pair of valve discs; wherein the axial movement of the valve stem structure causes the first wedge-shaped member to come into sliding contact with the valve disc, and causes the valve disc to move toward the valve seat; Wherein, the abutment block is arranged at the center position of the wedge-shaped member.

9. The valve disc assembly according to claim 8, characterized in that The end faces of the valve disc facing each other have: a second wedge-shaped member; The second wedge surface of the second wedge-shaped member is in slidable contact with the first wedge surface of the first wedge-shaped member.

10. A parallel double-disc gate valve using the assembly, characterized in that: At least: A valve disc assembly as claimed in any one of claims 1 to 9.

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