Double-mode sealing valve element for double-seat valve and double-seat valve with double-mode sealing valve element

Abstract

The invention relates to the technical field of valve elements of double-seat valves, in particular to a bimodal sealing valve element for a double-seat valve and the double-seat valve thereof.The bimodal sealing valve element comprises a valve rod and a guide rod which are coaxially arranged, an upper valve element is arranged on the valve rod, a lower valve element is arranged on the guide rod, and the upper valve element is arranged above the lower valve element; a pre-tightening mechanism is arranged between the lower end of the valve rod and the upper end of the lower guide rod and used for providing pre-tightening force to the guide rod when the upper valve element makes contact with the upper valve seat for sealing under the thrust effect of the valve rod, and the sealing face of the lower valve element and the sealing face of the lower valve seat are gradually and tightly attached. When the dual-mode sealing valve element for the dual-seat valve and the dual-seat valve thereof are used, an original dual-valve-element structure is arranged to be of a split type, when the valve rod applies acting force, the upper valve element is firstly in contact sealing with the upper valve seat, the acting force is transmitted to the guide rod through the pre-tightening mechanism, the sealing face of the lower valve element and the sealing face of the lower valve seat are gradually and tightly attached, and therefore the sealing effect of the dual-mode sealing valve element is achieved. Synchronous sealing of the upper and lower valve cores is realized, and leakage paths are reduced.

Description

Technical Field

[0001] The invention relates to the technical field of double-seat valve cores, in particular to a double-mode sealing valve core for a double-seat valve and the double-seat valve. Background Art

[0002] As a high-performance control valve, double-seat valves are widely used in the chemical and petrochemical industries, the power industry, the metallurgical and energy industries, and the environmental protection and water treatment industries. With the rapid development of industries such as petrochemicals, power, metallurgy, and pharmaceuticals, the requirements for media regulation in process are becoming increasingly complex. Traditional single-seat valves are prone to generating excessive unbalanced forces under high differential pressure conditions, resulting in shortened valve life and reduced control accuracy. Double-seat valves, with their unique balanced valve core structure, effectively address this problem, becoming a key control component in these complex operating conditions.

[0003] as follows Figure 1 As shown in the figure, although double-seat valves perform excellently in high-pressure differential and high-flow control, their dual-seat upper sealing spool structure also brings some inherent sealing limitations. The leakage risks caused by its structural characteristics require special attention: First, it is difficult to close the two sealing surfaces synchronously. Since the upper and lower valve cores of the double-seat valve must fit tightly against both valve seats at the same time, in actual operation, due to machining accuracy, installation deviation, or wear, the two sealing surfaces are difficult to close completely synchronously. Especially under low-pressure differential conditions, "one-sided leakage" is prone to occur, where only one valve seat is sealed and the other side is not fully closed. Second, there are inherent leakage paths. Compared with the single sealing surface of the single-seat valve, the dual sealing surface design of the double-seat valve increases the potential leakage points. Even if the seal on one side fails, the medium may still leak through the incompletely closed gap on the other side, especially in scenarios with strict bidirectional sealing requirements. This design aims to solve the problem of the difficulty of synchronous closing of the double-seat valve, so that the double-seat valve can further improve its sealing performance. Summary of the Invention

[0004] The technical problem to be solved by the present invention is: in order to solve the problem that the structure of the sealing valve core of the existing double-seat valve is difficult to close completely and synchronously due to the influence of processing accuracy, installation deviation or wear, especially under low pressure difference conditions, "one-sided leakage" is prone to occur. A dual-modal sealing valve core for a double-seat valve and a double-seat valve are now provided.

[0005] The technical solution adopted by the present invention to solve its technical problems is: a dual-mode sealing valve core for a double-seat valve, including a coaxially arranged valve stem and a guide rod, wherein the valve stem is provided with an upper valve core, the guide rod is provided with a lower valve core, the upper valve core is arranged above the lower valve core, and a pre-tightening mechanism is provided between the lower end of the valve stem and the upper end of the lower guide rod. The pre-tightening mechanism is used to provide a pre-tightening force to the guide rod when the upper valve core contacts the upper valve seat for sealing under the action of the valve stem thrust, and gradually form a tight fit between the sealing surface of the lower valve core and the lower valve seat. Compared with the existing technology, this solution sets the original dual-valve core structure into a split type, wherein when the valve stem applies a force, the upper valve core first contacts and seals with the upper valve seat, and the force is transmitted to the guide rod through the pre-tightening mechanism, and gradually form a tight fit between the sealing surface of the lower valve core and the lower valve seat, thereby achieving synchronous sealing of the upper and lower valve cores, reducing leakage paths, and avoiding the problem of inability to synchronize sealing due to processing errors, installation errors and wear.

[0006] In order to realize the pre-tightening mechanism, some preferred embodiments include an elastic element, a connecting rod is provided at the upper end of the guide rod located at the lower valve core, one end of the connecting rod is slidably provided at the lower end of the valve stem, the elastic element is provided between the connecting rod and the valve stem, and the valve stem is provided with a limit mechanism for limiting the sliding range of the guide rod. By sliding one end of the connecting rod on the guide rod against one end of the valve stem and cooperating with the elastic element, the pre-tightening force is transmitted and the sealing surface of the lower valve core and the lower valve seat gradually forms a tight fit, thus realizing the pre-tightening mechanism.

[0007] To enable the connecting rod to slide on the valve stem, some preferred embodiments include a bushing at the lower end of the valve stem. One end of the connecting rod matches the bushing, passes through the bushing, and rests against the elastic element. By providing the bushing on the valve stem, one end of the connecting rod slides within the bushing. Due to frequent operation, axial sliding between the guide rod and the valve stem is achieved by sliding between the bushing and the connecting rod. The bushing reduces friction and wear between the two, and facilitates support and positioning.

[0008] To facilitate installation of the bushing on the valve stem, in some preferred embodiments, a placement hole is defined along the axial direction of the lower end of the valve stem, the elastic element is disposed within the placement hole, and the bushing is threadedly connected to the placement hole. By defining the placement hole on the valve stem and threading the placement hole and bushing together, the bushing can be quickly installed or removed from the valve stem.

[0009] To prevent the guide rod from disengaging from the valve stem, in some preferred embodiments, the limiting mechanism includes a limiting shoulder provided at one end of the connecting rod, the limiting shoulder matching the placement hole, the limiting shoulder slidingly disposed within the placement hole, and the limiting shoulder being located between the elastic element and the bushing. By providing a limiting shoulder at one end of the connecting rod and sliding the limiting shoulder within the placement hole, the limiting shoulder is simultaneously constrained between the elastic element and the bushing, effectively preventing the guide rod from disengaging from the valve stem.

[0010] In order to realize the elastic element, in some preferred embodiments, the elastic element is a disc spring.

[0011] In order to prevent the connecting rod from being too large when compressing the elastic element, causing the disc spring to fail due to overload, in some preferred embodiments, the connecting rod is provided with a boss at one end of the elastic element, and the boss is used to prevent the disc spring from overloading.

[0012] In some preferred embodiments, the disc spring is made of a material with a high elastic coefficient.

[0013] In some preferred embodiments, the material of the bushing is the same as that of the upper valve core.

[0014] A double-seat valve is provided with the above-mentioned double-mode sealing valve core for the double-seat valve.

[0015] The beneficial effects of the present invention are as follows: when the dual-mode sealing valve core for the double-seat valve of the present invention and the double-seat valve are in use, the original double-seat valve core structure is set to a split type, wherein when the valve stem applies a force, the upper valve core first contacts and seals with the upper valve seat, and transmits the force to the guide rod through the pre-tightening mechanism, and gradually forms a tight fit between the sealing surface of the lower valve core and the lower valve seat, thereby realizing synchronous sealing of the upper and lower valve cores, reducing the leakage path, and avoiding the structure of the sealing valve core of the existing double-seat valve, which is difficult to completely and synchronously close the two sealing surfaces due to the influence of processing accuracy, installation deviation or wear, especially under low pressure difference working conditions, and is prone to the problem of "one-sided leakage". BRIEF DESCRIPTION OF THE DRAWINGS

[0016] The present invention will be further described below with reference to the accompanying drawings and examples.

[0017] Figure 1 It is a structural diagram of the valve core in the prior art; Figure 2 It is a structural schematic diagram of the valve core in the present invention; Figure 3 yes Figure 2 A partial enlarged view of middle A; Figure 4 This is the state of the valve core in the present invention when it is used. Figure 1 ; Figure 5 yes Figure 4A partial enlarged view of middle B; Figure 6 This is the state of the valve core in the present invention when it is used. Figure 2 ; Figure 7 yes Figure 6 A partial enlarged view of C in the middle.

[0018] In the figure: 1. valve stem, 2. guide rod, 3. upper valve core, 4. lower valve core, 5. upper valve seat, 6. lower valve seat, 7. elastic element, 8. connecting rod, 9. bushing, 10. placement hole, 11. limit shaft shoulder, 12. boss. DETAILED DESCRIPTION

[0019] The present invention is further described in detail below in conjunction with the embodiments: The present invention is not limited to the following specific embodiments. Based on the disclosure of the present invention, a person skilled in the art may adopt a variety of other specific embodiments to implement the present invention. Any simple changes or modifications made to the design structure and concept of the present invention fall within the scope of protection of the present invention. It should be noted that the embodiments and features of the embodiments of the present invention may be combined with each other unless they conflict.

[0020] In the description of the present invention, it should be understood that the terms "center", "longitudinal", "lateral", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside" and the like indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as limiting the present invention. In addition, the terms "first", "second", etc. are only used for descriptive purposes and cannot be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Therefore, features defined as "first", "second", etc. may explicitly or implicitly include one or more of the features. In the description of the present invention, unless otherwise specified, "multiple" means two or more.

[0021] In the description of the present invention, it should be noted that, unless otherwise expressly specified or limited, the terms "mounted," "connected," and "connected" should be understood in a broad sense. For example, they may refer to fixed connections, detachable connections, or integral connections; mechanical connections or electrical connections; direct connections or indirect connections through an intermediate medium; and internal communication between two components. Those skilled in the art will understand the specific meanings of the above terms in the present invention based on specific circumstances.

[0022] Example 1, as Figure 1As shown in FIG, an upper valve core 3 and a lower valve core 4 are welded on the existing valve stem 1. Since the upper and lower valve cores 4 of the double-seat valve need to fit tightly with the two valve seats at the same time, in actual operation, due to the influence of processing accuracy, installation deviation or wear, it is difficult for the two sealing surfaces to close completely synchronously, especially under low pressure difference working conditions. Therefore, the structure of the existing valve core is prone to "one-side leakage", that is, only one valve seat is sealed and the other side is not completely closed. In order to solve the above-mentioned "one-side leakage" problem, as shown in FIG. Figure 2-7 As shown, this embodiment provides a dual-mode sealing valve core for a double-seat valve, including a valve stem 1 and a guide rod 2. The valve stem 1 is slidably arranged above the guide rod 2 and is coaxially arranged. An upper valve core 3 is arranged on the valve stem 1, and a lower valve core 4 is arranged on the guide rod 2. The upper valve core 3 is arranged above the lower valve core 4. A pre-tightening mechanism is provided between the lower end of the valve stem 1 and the upper end of the lower guide rod 2. The pre-tightening mechanism is used to provide a pre-tightening force to the guide rod 2 when the upper valve core 3 contacts the upper valve seat 5 for sealing under the action of thrust of the valve stem 1, and to gradually form a tight fit between the sealing surfaces of the lower valve core 4 and the lower valve seat 6.

[0023] The pre-tightening mechanism includes an elastic element 7, a connecting rod 8 is provided at the upper end of the guide rod 2 located at the lower valve core 4, one end of the connecting rod 8 is slidably set at the lower end of the valve stem 1, the elastic element 7 is set between the connecting rod 8 and the valve stem 1, and a limiting mechanism is provided on the valve stem 1 for limiting the sliding range of the guide rod 2.

[0024] The lower end of the valve stem 1 is provided with a placement hole 10 along its axial direction, the elastic element 7 is arranged in the placement hole 10, and the bushing 9 is threadedly connected in the placement hole 10, so that the bushing 9 is arranged at the lower end of the valve stem 1, one end of the connecting rod 8 matches the bushing 9, and one end of the connecting rod 8 passes through the bushing 9 and rests on the elastic element 7.

[0025] The limiting mechanism includes a limiting shoulder 11 arranged at one end of the connecting rod 8, the limiting shoulder 11 matches the placement hole 10, the limiting shoulder 11 is slidably arranged in the placement hole 10, the cross-section of the limiting shoulder 11 is larger than the inner hole of the bushing 9, and the limiting shoulder 11 is located between the elastic element 7 and the bushing 9.

[0026] The elastic element 7 is a disc spring. The connecting rod 8 is located at one end of the elastic element 7 and is provided with a boss 12. The boss 12 is used to prevent the disc spring from being overloaded. The disc spring is made of a material with a high elastic coefficient.

[0027] In this embodiment, the material of the bushing 9 is the same as that of the upper valve core 3, the valve stem 1 is made of high-strength stainless steel, such as 316L, and the surface is hard chrome-plated to improve wear resistance. The upper valve core 3 and the lower valve core 4 are both made of welded Stellite alloy to ensure the durability of the sealing surface under high temperature and high pressure. The disc spring is made of a high elastic coefficient material, such as 60Si2MnA, with a preload range of 200-500N, and the compression stroke is strictly controlled at 1-2mm. The material of the bushing 9 and the material of the connecting rod 8 are consistent with those of the upper valve core 3 and the lower valve core 4 to ensure matching of thermal expansion coefficients.

[0028] Example 2, Example 2 is an application of Example 1, specifically: a double-seat valve, including a valve body, an upper valve seat 5 and a lower valve seat 6 are installed in the valve body, and a valve core is provided on the valve body. The valve core adopts the above-mentioned dual-mode sealing valve core for the double-seat valve.

[0029] When the above-mentioned dual-mode sealing valve core for the double-seat valve and the double-seat valve are in use, the precise synchronous closing of the double valve seats is achieved through staged sealing control. The specific operation process is as follows: The first stage, the pre-sealing stage, begins when the actuator drives the valve stem 1 downward. The lower valve core 4, driven by gravity and the thrust of the valve stem 1, preferentially contacts the lower valve seat 6. At this point, a rigid seal has not yet been formed between the lower valve core 4 and the lower valve seat 6; a slight gap of approximately 0.05-0.1 mm remains between them. An initial gap of 1-2 mm is maintained between the upper valve core 3 and the upper valve seat 5. The key to this stage is the flexible adjustment of the disc spring preload to prevent hard collisions caused by machining errors or installation deviations, while also providing a buffer for the second stage of sealing.

[0030] The second stage is the complete sealing stage: the actuator continues to apply thrust, and the valve stem 1 drives the spiral bushing 9 downward to compress the disc spring. The disc spring elastically deforms, and the disc spring compression stroke is 1-2mm, transmitting the preload force to the lower valve core 4, causing it to gradually form a tight fit with the lower valve seat 6. When the upper valve core 3 contacts the upper valve seat 5 under the thrust of the valve stem 1, the disc spring has reached its maximum compression and is controlled by the limit boss 12 of the connecting rod 8. At this time, the constant preload force provided by the disc spring is 200-500N, ensuring that the sealing surface pressure of the lower valve core 4 and the lower valve seat 6 is evenly distributed, eliminating the risk of sealing failure caused by thermal expansion or medium pressure fluctuations. The sealing action of the upper valve core 3 and the lower valve core 4 is achieved by staged closure through time difference control, which completely solves the problem of unilateral leakage caused by the difficulty of synchronous closure in traditional two-seat valves.

[0031] Valve stem 1 material and surface treatment: Made of high-strength stainless steel 316L, vacuum quenched and hard chrome plated with a thickness of ≥20μm, which significantly improves wear resistance and corrosion resistance. It is suitable for high temperature and particulate media environments with a temperature of ≤450℃.

[0032] The thread fit clearance between the bushing 9 and the valve stem 1 is strictly controlled within ±0.01mm, and through matching the thermal expansion coefficient, the material of the valve stem 1 is consistent with the valve core to avoid sticking problems caused by temperature differences.

[0033] Disc spring group and preload control, disc spring selection and parameters: 60Si2MnA spring steel is selected and treated with austempering process. The stiffness coefficient of a single disc spring is 50N / mm. It adopts a parallel laminated structure, with 2-5 single disc springs superimposed. The total preload can be adjusted in the range of 200-500N.

[0034] Limit protection mechanism: An annular limit boss 12 is designed at the end of the connecting rod 8. The height of the boss 12 is 2mm, which limits the compression stroke of the disc spring to no more than 2mm, prevents plastic deformation caused by overload, and ensures that the elastic recovery rate is ≥95%.

[0035] The assembly process is optimized for ease of assembly and maintenance. The disc spring assembly is embedded in the inner groove of the valve stem 1 to ensure that it is fully fitted with the upper limit section of the connecting rod 8. The spiral bushing 9 is screwed in to the preset torque of 20N•m and fixed by argon arc welding to prevent loosening. The lower valve core 4 is threadedly connected to the connecting rod 8, sealed with anaerobic adhesive, and then reinforced by spot welding. The entire assembly has been leak tested by helium mass spectrometry, with a leakage rate of ≤1×10⁻ 6 Pa•m³ / s, installed into the valve body later.

[0036] Modular maintenance design, independent replacement mechanism: The upper valve core 3, lower valve core 4, and disc spring assembly all adopt a modular quick-release structure. If a single sealing surface is worn, only the corresponding valve core needs to be removed without disassembling the entire valve body. After replacement, the preload can be recalibrated.

[0037] Maintenance cost comparison: Traditional double-seat valve maintenance requires replacement of the entire valve core, while this design supports partial replacement, reducing maintenance costs by 84%.

[0038] Performance improvement and measured data, sealing level verification: After third-party testing, this design has a leakage rate of ≤0.001%Kv under a two-way pressure differential of 10MPa, meeting the ANSIV level sealing standard, which is one level higher than traditional double-seat valves.

[0039] Application scenarios have been expanded. This design is particularly suitable for the following harsh working conditions: petrochemical industry, emergency shut-off valves for high-temperature oil pipelines; nuclear power systems, precise flow control of primary boric acid injection valves; coal chemical industry, high-pressure ash water regulating valves for coal gasification units, LNG storage and transportation: two-way sealed shut-off valves in ultra-low temperature environments, with a temperature of -196°C.

[0040] Through the above technical solutions, the dual-mode sealing valve core DSSV has achieved comprehensive breakthroughs in sealing reliability, maintenance economy and adaptability to working conditions, providing an innovative solution for the field of industrial control valves.

[0041] The above description of the preferred embodiments of the present invention is intended to serve as a guide. Based on the above description, relevant personnel are fully capable of making various changes and modifications without departing from the technical scope of this invention. The technical scope of this invention is not limited to the contents of the specification and must be determined according to the scope of the claims.

Claims

1. A dual-mode sealing valve core for a double-seat valve, characterized by: The invention comprises a coaxially arranged valve stem (1) and a guide rod (2), wherein the valve stem (1) is provided with an upper valve core (3), the guide rod (2) is provided with a lower valve core (4), the upper valve core (3) is arranged above the lower valve core (4), and a pre-tightening mechanism is provided between the lower end of the valve stem (1) and the upper end of the lower guide rod (2), and the pre-tightening mechanism is used to provide a pre-tightening force to the guide rod (2) when the upper valve core (3) contacts the upper valve seat (5) for sealing under the action of thrust of the valve stem (1), and to gradually form a tight fit between the sealing surface of the lower valve core (4) and the lower valve seat (6).

2. The dual-mode sealing valve core for a double-seat valve according to claim 1, characterized in that: The pre-tightening mechanism includes an elastic element (7), a connecting rod (8) is provided at the upper end of the guide rod (2) located on the lower valve core (4), one end of the connecting rod (8) is slidably provided at the lower end of the valve stem (1), the elastic element (7) is provided between the connecting rod (8) and the valve stem (1), and a limiting mechanism for limiting the sliding range of the guide rod (2) is provided on the valve stem (1).

3. The dual-mode sealing valve core for a double-seat valve according to claim 2, characterized in that: A bushing (9) is provided at the lower end of the valve stem (1), one end of the connecting rod (8) matches the bushing (9), and one end of the connecting rod (8) passes through the bushing (9) and abuts against the elastic element (7).

4. The dual-mode sealing valve core for a double-seat valve according to claim 3, characterized in that: The lower end of the valve stem (1) is provided with a placement hole (10) along its axial direction, the elastic element (7) is arranged in the placement hole (10), and the bushing (9) is threadedly connected in the placement hole (10).

5. The dual-mode sealing valve core for a double-seat valve according to claim 4, characterized in that: The limiting mechanism comprises a limiting shoulder (11) arranged at one end of the connecting rod (8), the limiting shoulder (11) matches the placement hole (10), the limiting shoulder (11) is slidably arranged in the placement hole (10), and the limiting shoulder (11) is located between the elastic element (7) and the bushing (9).

6. The dual-mode sealing valve core for a double-seat valve according to any one of claims 2 to 5, characterized in that: The elastic element (7) is a disc spring.

7. The dual-mode sealing valve core for a double-seat valve according to claim 6, characterized in that: A boss (12) is provided at one end of the connecting rod (8) located on the elastic element (7), and the boss (12) is used to prevent the disc spring from being overloaded.

8. The dual-mode sealing valve core for a double-seat valve according to claim 6, characterized in that: The disc spring is made of a material with a high elastic coefficient.

9. The dual-mode sealing valve core for a double-seat valve according to claim 3, characterized in that: The material of the bushing (9) is the same as that of the upper valve core (3).

10. A double-seat valve, characterized in that: A dual-mode sealing valve core for a double-seat valve according to any one of claims 1 to 9 is installed.

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