A minimum flow valve

Abstract

The utility model provides a minimum flow valve, include: forged valve body has the medium entrance, medium cavity and medium export with each other intercommunication, valve seat sets up in the medium cavity, labyrinth type throttling subassembly is connected with valve seat, its along the axial direction is equipped with medium passage, along the radial direction is equipped with throttling flow channel, medium passage communicates with medium entrance, throttling flow channel is used for the intercommunication medium passage with medium export, valve plug, slide setting in the medium passage, valve rod, connect valve plug with actuating mechanism, forged valve cover is connected with forged valve body. High pressure medium passes through the throttling pressure reduction of labyrinth type throttling subassembly and discharges from medium export, because valve plug is located in the medium passage, valve seat is located in the medium cavity, the flash evaporation cavitation occurs at the medium export, therefore, the sealing surface of valve plug, valve seat will not be affected by the cavitation erosion, improved the reliability of valve seal. The application adopts forged valve body, forged valve cover, effectively reduces the gravity center of valve, improves the inherent frequency of complete machine, thereby improves the anti shock performance.

Description

Technical Field

[0001] This utility model relates to the field of valve technology, and in particular to a minimum flow valve. Background Technology

[0002] The minimum flow valve operating condition is characterized by high temperature, high pressure differential, high sealing requirements, severe flash cavitation, and large valve vibration. For ordinary valves, after the medium is throttled and depressurized, severe flash cavitation occurs, which damages the valve plug or valve seat sealing surface and induces valve vibration and even the vibration of the entire pipeline, causing safety accidents.

[0003] Currently, for minimum flow valve operation, existing technologies mainly focus on improving the internal structure to prevent flash cavitation, attempting to fundamentally solve the problem. However, due to the high temperature and pressure differential characteristics of minimum flow conditions, flash cavitation can only be mitigated, not eliminated. Therefore, internal leakage and vibration caused by flash cavitation are unavoidable. Existing solutions only improve the anti-flash cavitation performance of internal components, without considering countermeasures for valve vibration induced by unavoidable flash cavitation. Consequently, prolonged use under minimum flow conditions can lead to valve malfunction and even safety accidents. Utility Model Content

[0004] This utility model provides a minimum flow valve to solve the problem that existing minimum flow valves only improve the anti-flash cavitation performance of internal components, without considering countermeasures for valve vibration induced by unavoidable flash cavitation. After long-term use, this can lead to valve malfunction or even safety accidents.

[0005] This utility model provides a minimum flow valve, comprising: The forged valve body has an interconnected medium inlet, medium cavity, and medium outlet; A valve seat is connected to the forged valve body, and the valve seat is disposed within the medium cavity; A labyrinth-type throttling assembly is connected to the valve seat. The labyrinth-type throttling assembly is disposed in the medium cavity. The labyrinth-type throttling assembly has a medium channel along the axial direction and a throttling channel along the radial direction. The medium channel is connected to the medium inlet, and the throttling channel is used to connect the medium channel to the medium outlet. A valve plug is slidably disposed within the medium channel, and the valve plug is used to cooperate with the valve seat to block the medium channel from the medium inlet; A valve stem connects the valve plug to the actuator. The actuator drives the valve stem to move the valve plug axially along the medium channel to switch the opening and closing of the medium channel and the medium inlet. A forged valve cover is connected to the forged valve body, and the valve stem extends through the forged valve cover and is connected to the actuator.

[0006] In one embodiment of the present invention, a bracket is further included. The bracket is connected to the forged valve cover and is used to support the actuator. The forged valve cover is provided with a limiting post, and the bracket is provided with a limiting hole. The limiting hole and the limiting post are in clearance fit.

[0007] In one embodiment of the present invention, a packing component is further included. The packing component fills the space between the valve stem and the forged valve cover to seal the medium cavity. A packing gland is connected to the forged valve cover to provide preload for the packing component.

[0008] In one embodiment of the present invention, the limiting post is provided with a first threaded hole, the packing gland is provided with a first through hole, the first through hole is used to pass through the first stud and be threadedly connected to the first threaded hole, the first stud is threadedly connected with a first nut, and a disc spring is provided between the first nut and the packing gland.

[0009] In one embodiment of the present invention, the labyrinth-type throttling component includes multiple labyrinth-type throttling plates, which are stacked to form the labyrinth-type throttling component, and the throttling channel is disposed on the labyrinth-type throttling plates.

[0010] In one embodiment of the present invention, the valve plug has a plurality of balance holes distributed circumferentially, and the balance holes penetrate the valve plug along the axial direction of the valve stem.

[0011] In one embodiment of the present invention, the sealing surface of the valve plug and the sealing surface of the valve seat have an included angle α, wherein the included angle α is 2°~5°.

[0012] In one embodiment of the present invention, the forged valve body is provided with a second threaded hole, the forged valve cover is provided with a second through hole, the second through hole is used to pass through a second stud and be threadedly connected to the second threaded hole, a second nut is threadedly connected to the second stud, and a first anti-loosening washer is provided between the second nut and the forged valve cover.

[0013] In one embodiment of the present invention, the bracket, the forged valve cover, and the actuator are all connected by bolts, and a second anti-loosening washer is provided between the bolts and the bracket and the actuator.

[0014] In one embodiment of this utility model, the valve stem and the push rod of the actuator are connected by a slotted nut assembly. The slotted nut assembly includes an upper clamping block and a lower clamping block. The upper clamping block is threadedly connected to the push rod, and the lower clamping block is threadedly connected to the valve stem. The upper clamping block has a positioning through hole, and the lower clamping block has a positioning screw hole coaxially with the positioning through hole. The positioning through hole is used to pass a positioning bolt and be threadedly connected to the positioning screw hole. The upper clamping block has an adjustment through hole, and the lower clamping block has an adjustment screw hole corresponding to the adjustment through hole. The diameter of the adjustment through hole is larger than that of the adjustment screw hole, and the adjustment through hole is used to pass an adjustment bolt and be threadedly connected to the adjustment screw hole.

[0015] The beneficial effects of this utility model are as follows: The minimum flow valve proposed in this utility model effectively enhances the structural strength of the valve by using a forged valve body and a forged valve cover, and lowers the center of gravity of the valve as a whole, thereby increasing the natural frequency of the whole machine and improving its seismic performance. The use of a labyrinth-type throttling component can effectively reduce flash cavitation, and since flash cavitation occurs at the medium outlet, it can prevent the sealing surfaces of the valve seat and valve plug from being affected by cavitation, thereby extending the service life of the valve. Attached Figure Description

[0016] The accompanying drawings, which are incorporated in and form part of this specification, illustrate embodiments consistent with this application and, together with the description, serve to explain the principles of this application. It is obvious that the drawings described below are merely some embodiments of this application, and those skilled in the art can obtain other drawings based on these drawings without any inventive effort.

[0017] In the attached diagram: Figure 1 A cross-sectional structural schematic diagram of a minimum flow valve provided in an embodiment of this utility model; Figure 2 for Figure 1 Enlarged schematic diagram of the structure of section A in the middle; Figure 3 for Figure 1 Enlarged schematic diagram of the structure of section B in the middle; Figure 4 This is a partially enlarged schematic diagram of the valve plug and valve seat in the closed state of the minimum flow valve provided in an embodiment of the present invention.

[0018] The attached figures are labeled as follows: 1. Forged valve body, 101 medium inlet, 102 medium cavity, 103 medium outlet, 2. Valve seat, 3. Labyrinth-type throttling assembly, 3. Medium channel, 301 medium plug, 4. Balance hole, 401 valve stem, 5. Actuator, 6. Forged valve cover, 7. Limiting post, 701, bracket, 8. Packing assembly, 9. Packing gland, 10. First stud, 11. First nut, 12. Disc spring, 13. Second stud, 14. Second nut, 15. First anti-loosening washer, 16. Bolt, 17. Second anti-loosening washer, 18. Slit nut assembly, 19. Upper clamping block, 1901, lower clamping block, 1902, positioning bolt, 20. Adjusting bolt, 21. Compensation gap, 2101, guide ring, 22. First sealing ring, 23. Second sealing ring, 24. Third sealing ring, 25. Fourth sealing ring, 26. Third anti-loosening washer, 27. Detailed Implementation

[0019] The following specific examples illustrate the implementation of this utility model. Those skilled in the art can easily understand other advantages and effects of this utility model from the content disclosed in this specification. This utility model can also be implemented or applied through other different specific embodiments. Various details in this specification can also be modified or changed based on different viewpoints and applications without departing from the spirit of this utility model. In the absence of conflict, the following embodiments and features in the embodiments can be combined with each other.

[0020] It should be noted that the illustrations provided in the following embodiments are only schematic representations of the basic concept of the present invention. The drawings only show the components related to the present invention and are not drawn according to the actual number, shape and size of the components. In actual implementation, the form, quantity and proportion of each component can be arbitrarily changed, and the layout of the components may also be more complex.

[0021] In the following description, numerous details are explored to provide a more thorough explanation of embodiments of the present invention. However, it will be apparent to those skilled in the art that embodiments of the present invention may be practiced without these specific details. In other embodiments, well-known structures and devices are shown in block diagram form rather than in detail to avoid obscuring embodiments of the present invention.

[0022] Please combine Figures 1 to 4 As shown, this utility model provides a minimum flow valve.

[0023] In one exemplary embodiment of this application, the minimum flow valve includes: The forged valve body 1 has a medium inlet 101, a medium cavity 102 and a medium outlet 103 that are interconnected. Valve seat 2 is connected to the forged valve body 1 and is disposed in the medium cavity 102; The labyrinth-type throttling assembly 3 is connected to the valve seat 2. The labyrinth-type throttling assembly 3 is disposed in the medium cavity 102. The labyrinth-type throttling assembly 3 has a medium channel 301 along the axial direction and a throttling channel along the radial direction. The medium channel 301 is connected to the medium inlet 101, and the throttling channel is used to connect the medium channel 301 and the medium outlet 103. Valve plug 4 is slidably disposed in the medium channel 301. Valve plug 4 is used to cooperate with valve seat 2 to block the medium channel 301 from the medium inlet 101. The valve stem 5 connects the valve plug 4 and the actuator 6. The actuator 6 is used to drive the valve stem 5 to move the valve plug 4 along the axial direction of the medium channel 301 to switch the opening and closing of the medium channel 301 and the medium inlet 101. The forged valve cover 7 is connected to the forged valve body 1, and the valve stem 5 extends out of the forged valve cover 7 and is connected to the actuator 6.

[0024] In this embodiment, the medium inlet 101 and medium outlet 103 of the forged valve body 1 are connected to the pipeline by butt welding or flange connection. The flange connection form and the flow channels of the medium inlet 101 and medium outlet 103 can be designed and determined according to the on-site pipeline connection form and nominal diameter, avoiding the welding diameter change problem caused by the inconsistency between the flow channel diameter of the cast valve body and the pipeline diameter. Furthermore, the forged valve body 1 has a high material density, higher structural strength, and fewer defects, making it more suitable for flash evaporation air handling conditions. The forged valve body 1 is also heavier, which lowers the center of gravity of the regulating valve after assembly, increases the valve's natural frequency, and improves its seismic resistance. In this embodiment, high-pressure medium enters through the medium inlet 101, and after being throttled and depressurized by the labyrinth-type throttling component 3 installed in the medium cavity 102, it is discharged from the medium outlet 103. The flow channel of the valve seat 2 is coaxially arranged with the medium channel 301, and the valve plug 4 is located inside the medium channel 301. Therefore, the sealing surfaces of the valve seat 2 and the valve plug 4 are both located inside the high-pressure medium cavity 102. The flash cavitation of the medium after throttling and depressurization occurs at the medium outlet 103, located outside the medium channel 301. The sealing surfaces of the valve seat 2 and the valve plug 4 are not affected by flash cavitation cavitation cavitation, ensuring the reliability of the valve seal. Furthermore, by setting the labyrinth-type throttling component 3 to depressurize the medium in multiple stages, the flash cavitation phenomenon of the minimum flow valve is greatly reduced. In this embodiment, a forged valve body 1 and a forged valve cover 7 are used, which effectively enhances the structural strength of the valve and lowers the overall center of gravity of the valve, increasing the natural frequency of the entire machine, thereby improving the seismic performance.

[0025] In an exemplary embodiment of this application, a bracket 8 is also included. The bracket 8 is connected to the forged valve cover 7 and is used to support the actuator 6. The forged valve cover 7 is provided with a limiting post 701, and the bracket 8 is provided with a limiting hole. The limiting hole and the limiting post 701 are in clearance fit.

[0026] In this embodiment, the bracket 8 is a cylindrical hollow bracket 8. The bracket 8 adopts a ring structure and the wall thickness of the bracket 8 is thickened, which effectively improves the structural strength and heat dissipation area of ​​the bracket 8. The positioning installation is achieved by the cooperation of the limiting hole and the limiting post 701, which can quickly position the connection between the bracket 8 and the forged valve cover 7, and the limiting post 701 can achieve radial limiting of the bracket 8. By having multiple rectangular heat dissipation holes distributed circumferentially on the bracket 8, and the rectangular heat dissipation holes extending along the axial direction of the bracket 8, the ventilation performance of the bracket 8 structure can be improved through the heat dissipation holes, thereby ensuring that the accessories on the bracket 8 are within the allowable operating temperature range.

[0027] In an exemplary embodiment of this application, a packing component 9 is also included. The packing component 9 is filled between the valve stem 5 and the forged valve cover 7 to seal the medium cavity 102. A packing gland 10 is connected to the forged valve cover 7 to provide preload force for the packing component 9.

[0028] In this embodiment, the gap between the valve stem 5 and the forged valve cover 7 is sealed by the packing component 9 to prevent the medium from leaking out from the gap between the valve stem 5 and the forged valve cover 7; the packing component 9 provides sealing pre-tightening force through the packing gland 10 connected to the forged valve cover 7, thereby achieving the sealing effect of the packing component 9 at the gap.

[0029] In another exemplary embodiment, a guide ring 22 is provided between the forged valve cover 7 and the labyrinth-type throttling assembly 3 within the medium cavity 102. The guide ring 22 is used to guide the axial movement of the valve plug 4 along the medium channel 301 to prevent the valve plug 4 from shifting.

[0030] In another exemplary embodiment, a first sealing ring 23 is provided between the guide ring 22 and the valve plug 4. The first sealing ring 23 is used to seal the gap between the valve plug 4 and the guide ring 22 to prevent the medium from leaking internally from the mating gap between the guide ring 22 and the valve plug 4.

[0031] In yet another exemplary embodiment, a second sealing ring 24 is provided between the guide ring 22 and the forged valve body 1, the second sealing ring 24 being used to seal the gap between the guide ring 22 and the forged valve body 1.

[0032] In yet another exemplary embodiment, a third sealing ring 25 is provided between the guide ring 22 and the forged valve cover 7, the third sealing ring 25 being used to seal the gap between the guide ring 22 and the forged valve cover 7.

[0033] In yet another exemplary embodiment, a fourth sealing ring 26 is provided between the valve seat 2 and the forged valve body 1, the fourth sealing ring 26 being used to seal the gap between the forged valve body 1 and the valve seat 2.

[0034] By setting the first sealing ring 23, the second sealing ring 24, the third sealing ring 25, and the fourth sealing ring 26, the problem of leakage of the medium in the valve body at the connection gaps of various components is effectively prevented.

[0035] In an exemplary embodiment of this application, the limiting post 701 is provided with a first threaded hole, the packing gland 10 is provided with a first through hole, the first through hole is used to pass through the first stud 11 and be threadedly connected to the first threaded hole, the first stud 11 is threadedly connected with a first nut 12, and a disc spring 13 is provided between the first nut 12 and the packing gland 10.

[0036] In this embodiment, under the elastic force of the disc spring 13, the threads between the first stud 11 and the first nut 12 are pressed together to generate a large frictional force, which effectively prevents the first stud 11 and the first nut 12 from loosening under vibration conditions. Furthermore, when the valve is used for a long time and the packing wears, the disc spring 13 releases a portion of the preload force to tighten the packing gland 10, compensating for the wear of the packing component 9, ensuring the sealing performance of the packing component 9, and thus preventing the medium from leaking out.

[0037] In an exemplary embodiment of this application, the labyrinth-type throttling component 3 includes multiple labyrinth-type throttling plates, which are stacked to form the labyrinth-type throttling component 3, and the throttling channel is disposed on the labyrinth-type throttling plates.

[0038] In this embodiment, a multi-stage labyrinth-type throttling and pressure-reducing structure is adopted. Each layer of labyrinth-type throttling plates is designed with labyrinth-type throttling grooves, which are stacked and combined to form a closed flow channel. Compared with the orifice-type multi-stage pressure-reducing structure, the multi-stage labyrinth-type throttling component 3 has better step-by-step pressure reduction effect and anti-flash cavitation performance, greatly reducing the flash cavitation phenomenon. In addition, the medium flow direction of the labyrinth-type throttling component 3 is designed to flow from the inside to the outside. The width of the labyrinth-type throttling groove gradually increases with the flow direction, so that the pressure drop decreases step by step with the flow direction, ensuring the pressure drop of the last stage and avoiding the flash cavitation phenomenon as much as possible. If it cannot be avoided, flash cavitation will occur at the outlet and rear end of the throttling component, protecting the sealing surfaces of the valve plug 4 and valve seat 2 from the influence of cavitation.

[0039] In an exemplary embodiment of this application, the valve plug 4 has a plurality of balance holes 401 distributed circumferentially, and the balance holes 401 penetrate the valve plug 4 along the axial direction of the valve stem 5.

[0040] In this embodiment, during the opening and closing process of the valve, the medium can quickly enter the upper part from the bottom through the balance hole 401 to balance the pressure of the valve plug 4 and reduce the output force requirement of the actuator 6 under high pressure conditions.

[0041] In an exemplary embodiment of this application, the sealing surface of the valve plug 4 and the sealing surface of the valve seat 2 have an included angle α, wherein the included angle α is 2°~5°.

[0042] In this embodiment, the sealing surfaces of the valve plug 4 and the valve seat 2 are designed with an angle difference α. The included angle α includes, but is not limited to, 2°, 3°, 4°, and 5°, which effectively increases the sealing specific pressure between the valve plug 4 and the valve seat 2, ensuring high sealing performance under minimum flow conditions. The valve plug 4 and the valve seat 2 are made of heat-treated high-hardness materials (such as 410 and 440 stainless steel) to improve the service life of the sealing components.

[0043] In an exemplary embodiment of this application, the forged valve body 1 is provided with a second threaded hole, the forged valve cover 7 is provided with a second through hole, the second through hole is used to pass through the second stud 14 and be threadedly connected to the second threaded hole, the second stud 14 is threadedly connected with a second nut 15, and a first anti-loosening washer 16 is provided between the second nut 15 and the forged valve cover 7.

[0044] In this embodiment, by providing a first anti-loosening washer 16 between the second nut 15 and the forged valve cover 7, the connection stability between the second nut 15 and the second stud 14 is ensured under vibration conditions, preventing the second nut 15 and the second stud 14 from loosening and falling off, which could lead to valve malfunction or safety accidents.

[0045] In an exemplary embodiment of this application, the bracket 8 is connected to the forged valve cover 7 and the actuator 6 by bolts 17, and a second anti-loosening washer 18 is provided between the bolts 17 and the bracket 8 and the actuator 6.

[0046] In this embodiment, by providing a second anti-loosening washer 18, the risk of bolt 17 falling off under vibration conditions is avoided.

[0047] In an exemplary embodiment of this application, the valve stem 5 and the push rod of the actuator 6 are connected by a slotted nut assembly 19. The slotted nut assembly 19 includes an upper clamping block 1901 and a lower clamping block 1902. The upper clamping block 1901 is threadedly connected to the push rod, and the lower clamping block 1902 is threadedly connected to the valve stem 5. The upper clamping block 1901 is provided with a positioning through hole, and the lower clamping block 1902 is provided with a positioning screw hole coaxially with the positioning through hole. The positioning through hole is used to pass through the positioning bolt 20 and be threadedly connected to the positioning screw hole. The upper clamping block 1901 is provided with an adjustment through hole, and the lower clamping block 1902 is provided with an adjustment screw hole corresponding to the adjustment through hole. The diameter of the adjustment through hole is larger than that of the adjustment screw hole, and the adjustment through hole is used to pass through the adjustment bolt 21 and be threadedly connected to the adjustment screw hole.

[0048] In this embodiment, the upper clamping block 1901 has an internal thread machined in its inner hole to match the push rod. It connects to the push rod via screwing, ensuring that the upper clamping block 1901 moves synchronously with the push rod. The lower clamping block 1902 is connected to the valve stem 5 using the same threaded connection. The positioning through hole in the upper clamping block 1901 and the positioning screw hole in the lower clamping block 1902 are designed as a coaxial structure. During assembly, the positioning bolt 20 is passed through the positioning through hole in the upper clamping block 1901, screwed into the positioning screw hole in the lower clamping block 1902, and tightened. The clearance between the positioning through hole and the positioning bolt 20 is extremely small, allowing the upper clamping block 1901 and the lower clamping block 1902 to move along the positioning bolt. Align the 20 axes to establish a positioning reference; adjust the diameter of the through hole to be larger than the diameter of the adjusting screw hole and the rod of the adjusting bolt 21 to form a radial compensation gap 2101. Under the premise that the positioning bolt 20 has established a reference, the compensation gap 2101 allows the upper clamping block 1901 and the lower clamping block 1902 to have a small relative displacement in the radial direction. This can effectively absorb the concentricity deviation of the push rod and the valve stem 5, the thread machining error and the angular deviation during assembly, and avoid the problems of valve stem 5 bending and increased movement resistance caused by forced alignment in traditional rigid connections. This ensures the coaxiality of the sealing surface of the valve plug 4 and the sealing surface of the valve seat 2 after assembly.

[0049] In another exemplary embodiment, a third anti-loosening washer 27 is provided between the adjusting bolt 21 and the upper clamping block 1901. The third anti-loosening washer 27 can reduce the risk of the adjusting bolt 21 falling off under the vibration condition of the valve.

[0050] Working principle: The medium inlet 101 and medium outlet 103 of the forged valve body 1 are connected to the pipeline by butt welding or flange connection. High-pressure medium enters through the medium inlet 101, and after being throttled and depressurized by the labyrinth-type throttling component 3 set in the medium cavity 102, it is discharged from the medium outlet 103. The flow channel of the valve seat 2 is coaxially arranged with the medium channel 301, and the valve plug 4 is located in the medium channel 301. Therefore, the sealing surface of the valve seat 2 and the sealing surface of the valve plug 4 are both located in the high-pressure medium cavity 102. The flash cavitation of the medium after throttling and depressurization occurs. At the medium outlet 103, located outside the medium channel 301, the sealing surfaces of the valve seat 2 and the valve plug 4 are not affected by flash cavitation cavitation, ensuring the reliability of the valve seal. Furthermore, by setting a labyrinth-type throttling component 3 to reduce the pressure of the medium in multiple stages, the flash cavitation phenomenon of the minimum flow valve is greatly reduced. In addition, this embodiment uses a forged valve body 1 and a forged valve cover 7, which effectively enhances the structural strength of the valve, lowers the center of gravity of the valve, and increases the natural frequency of the whole machine, thereby improving the seismic performance.

[0051] The above embodiments are merely illustrative of the principles and effects of this utility model and are not intended to limit the scope of this utility model. Any person skilled in the art can modify or alter the above embodiments without departing from the spirit and scope of this utility model. Therefore, all equivalent modifications or alterations made by those skilled in the art without departing from the spirit and technical concept disclosed in this utility model should still be covered by the claims of this utility model.

Claims

1. A minimum flow valve, characterized in that, include: The forged valve body has an interconnected medium inlet, medium cavity, and medium outlet; A valve seat is connected to the forged valve body, and the valve seat is disposed within the medium cavity; A labyrinth-type throttling assembly is connected to the valve seat. The labyrinth-type throttling assembly is disposed in the medium cavity. The labyrinth-type throttling assembly has a medium channel along the axial direction and a throttling channel along the radial direction. The medium channel is connected to the medium inlet, and the throttling channel is used to connect the medium channel to the medium outlet. A valve plug is slidably disposed within the medium channel, and the valve plug is used to cooperate with the valve seat to block the medium channel from the medium inlet; A valve stem connects the valve plug to the actuator. The actuator drives the valve stem to move the valve plug axially along the medium channel to switch the opening and closing of the medium channel and the medium inlet. A forged valve cover is connected to the forged valve body, and the valve stem extends through the forged valve cover and is connected to the actuator.

2. The minimum flow valve according to claim 1, characterized in that: It also includes a bracket, which is connected to the forged valve cover and is used to support the actuator. The forged valve cover is provided with a limiting post, and the bracket is provided with a limiting hole, which is clearance-fitted with the limiting post.

3. The minimum flow valve according to claim 2, characterized in that: It also includes a packing component that fills the space between the valve stem and the forged valve cover to seal the medium cavity. A packing gland is connected to the forged valve cover to provide preload for the packing component.

4. The minimum flow valve according to claim 3, characterized in that: The limiting post is provided with a first threaded hole, and the packing gland is provided with a first through hole. The first through hole is used to pass through the first stud and be threadedly connected to the first threaded hole. A first nut is threadedly connected to the first stud, and a disc spring is provided between the first nut and the packing gland.

5. The minimum flow valve according to claim 1, characterized in that: The labyrinth-type throttling assembly includes multiple labyrinth-type throttling plates, which are stacked to form the labyrinth-type throttling assembly, and the throttling channel is disposed on the labyrinth-type throttling plates.

6. The minimum flow valve according to claim 1, characterized in that: The valve plug has multiple balance holes distributed circumferentially, and the balance holes penetrate the valve plug along the axial direction of the valve stem.

7. The minimum flow valve according to claim 6, characterized in that: The sealing surface of the valve plug and the sealing surface of the valve seat have an included angle α, which is 2° to 5°.

8. The minimum flow valve according to claim 1, characterized in that: The forged valve body is provided with a second threaded hole, and the forged valve cover is provided with a second through hole. The second through hole is used to pass through a second stud and be threadedly connected to the second threaded hole. A second nut is threadedly connected to the second stud, and a first anti-loosening washer is provided between the second nut and the forged valve cover.

9. The minimum flow valve according to claim 2, characterized in that: The bracket, the forged valve cover, and the actuator are all connected by bolts, and a second anti-loosening washer is provided between the bolt and the bracket and the actuator.

10. The minimum flow valve according to claim 1, characterized in that: The valve stem and the push rod of the actuator are connected by a slotted nut assembly. The slotted nut assembly includes an upper clamping block and a lower clamping block. The upper clamping block is threadedly connected to the push rod, and the lower clamping block is threadedly connected to the valve stem. The upper clamping block has a positioning through hole, and the lower clamping block has a positioning screw hole coaxial with the positioning through hole. The positioning through hole is used to pass a positioning bolt and be threadedly connected to the positioning screw hole. The upper clamping block has an adjustment through hole, and the lower clamping block has an adjustment screw hole corresponding to the adjustment through hole. The diameter of the adjustment through hole is larger than that of the adjustment screw hole, and the adjustment through hole is used to pass an adjustment bolt and be threadedly connected to the adjustment screw hole.

Images