Multi-layer sleeve type pressure reducing and noise reducing regulating valve with plunger spool

Abstract

The utility model provides a kind of multilayer sleeve formula pressure reducing and noise reduction regulating valve with plunger valve core, including upper valve cover, valve body, valve seat, valve core subassembly and sleeve subassembly, sleeve subassembly includes concentric distribution from inside to outside first sleeve, second sleeve and third sleeve, wherein first sleeve inner diameter and valve core body outer diameter are adapted, first sleeve inner wall and valve core outer wall gap fit, and there are several first throttle orifices unevenly distributed on the side end cylinder wall of first sleeve close to valve seat;There are several second throttle orifices unevenly distributed on the cylinder wall of second sleeve;There are several third throttle orifices unevenly distributed on the cylinder wall of third sleeve.The utility model structure design is reasonable, adopts the design combination of plunger valve core and multilayer sleeve, designs flow window in the innermost layer of sleeve, disperses the harm of steam cavitation erosion to sealing surface after, in addition to the innermost layer first sleeve as flow window outside valve, there are second sleeve and third sleeve, fully weaken steam scouring harm, and simultaneously play the role of pressure reduction and noise reduction.

Description

Technical Field

[0001] This utility model relates to the field of valve design technology, and in particular to a multi-layer sleeve-type pressure-reducing and noise-reducing regulating valve with a plunger valve core. Background Technology

[0002] In the use of regulating valves in boiler feedwater systems, when the operating temperature is 165℃ (steam state), the inlet pressure is 17MPa, and the pressure difference is approximately 4.5MPa, existing regulating valves, such as... Figure 1 As shown, the double-guided cage-type single-seat regulating valve, in addition to having the characteristics of a single-seat valve, also has the advantages of good stability, erosion resistance, and cavitation resistance, making it more suitable for harsh working conditions.

[0003] A sleeve-type control valve (or simply sleeve valve) consists of a cylindrical sleeve installed within the valve body, with a valve plug that slides axially along the sleeve. The sleeve has a window with specific flow characteristics. By changing the flow area formed by the valve plug and the sleeve window, the flow rate is adjusted. It offers advantages such as good stability, long guiding length, smooth operation, simple structure, easy disassembly and assembly, and strong versatility. In a sleeve valve, the sealing surface and throttling surface are separate. The high-speed fluid at the throttling orifice impacts each other, and the energy is dissipated within the fluid itself, unlike a single-seat valve where the sealing surface is directly eroded. Therefore, in high-pressure differential applications, sleeve valves have a longer service life. Since the medium is at the bottom of the valve core, in the event of cavitation, the bursting of air bubbles generates an impact force that acts within the space below the valve core. This impact energy is absorbed by the medium itself, rather than acting on the valve core. In contrast, the impact energy of a single-seat valve acts directly on the valve core. Therefore, compared to a single-seat valve, a sleeve valve also has a certain degree of resistance to cavitation. In terms of noise reduction, since the energy of the sleeve valve is mostly consumed in the sleeve, and the dynamic pressure energy is consumed in the mutual impact, the noise generated by the sleeve valve is usually about 10dB lower than that of the single-seat valve.

[0004] Based on the above advantages, the following were adopted: Figure 1 The dual-guided cage-type single-seat regulating valve design shown features a perforated valve core and a double-layered sleeve. The initial design intention was to significantly reduce pressure and noise; however, its performance in the field was unsatisfactory, with severe erosion and cavitation issues appearing in the valve's internal components.

[0005] Through analysis and calculation, we learned that the problem was caused by a significant discrepancy between the actual operating parameters and the valve selection parameters. The actual pressure difference was 5.2 MPa, the valve cavity space was relatively large, and the valve was operating at its minimum operating condition with a very small opening. When the medium flowed through the valve core, the excessively small throttling area caused a sharp increase in flow velocity, while the pressure at that point dropped to the saturated vapor pressure. A considerable portion of the fluid vaporized during the pressure build-up process, resulting in significant damage to the valve. The unstable operating conditions at the site led to large fluctuations in the pressure difference. When high-speed fluid entered the upper cavity through the narrow channel of the valve core, according to Bernoulli's principle, the increased flow velocity led to a decrease in pressure. In localized areas, the pressure might drop below the saturated vapor pressure of the medium, causing it to vaporize and form bubbles. These bubbles, as they flowed to areas of higher pressure, would rapidly burst, generating localized high-pressure impacts and causing cavitation, which damaged the valve internals. Utility Model Content

[0006] The technical problem to be solved by this utility model is: in order to overcome the shortcomings of the prior art, this utility model provides a multi-layer sleeve type pressure reducing and noise reducing regulating valve with a plunger valve core, which disperses the harm of steam cavitation to the downstream of the valve and fully reduces the damage of steam scouring, thereby playing an effective role in pressure reducing and noise reducing.

[0007] The technical solution adopted by this utility model to solve its technical problem is as follows: a multi-layer sleeve-type pressure reducing and noise reducing regulating valve with a plunger valve core, including an upper valve cover, a valve body, a valve seat, and a valve core assembly. The valve body is divided into an inlet chamber and an outlet chamber. The inlet chamber is connected to the medium inlet of the valve body, and the outlet chamber is connected to the medium outlet of the valve body. The valve seat is fixed inside the valve body and located at the separation position between the inlet chamber and the outlet chamber. The valve core assembly includes a valve core body and a valve stem. The upper valve cover has a through mounting hole, and the valve stem extends into the outlet chamber of the valve body after passing through the mounting hole. The valve core body is fixed to the lower end of the valve stem. The valve core body is a plunger-type valve core. The valve seat has a flow hole connecting the inlet chamber and the outlet chamber. The lower end of the valve core body is adapted to the flow orifice; the valve core body rises with the valve stem away from the flow orifice, and the inlet and outlet are connected; the valve core body descends with the valve stem and abuts against the flow orifice, sealing the inlet and outlet; it includes a sleeve assembly, which is supported between the upper valve cover and the valve seat; the sleeve assembly includes a first-stage sleeve, a second-stage sleeve, and a third-stage sleeve concentrically distributed from the inside to the outside, wherein the inner diameter of the first-stage sleeve is adapted to the outer diameter of the valve core body, and the inner wall of the first-stage sleeve is clearance-fitted with the outer wall of the valve core; the first-stage sleeve has a number of first-stage throttling orifices staggered on the side wall near the valve seat; the second-stage sleeve has a number of second-stage throttling orifices staggered on the wall; and the third-stage sleeve has a number of third-stage throttling orifices staggered on the wall.

[0008] In the above scheme, a multi-layered sleeve assembly is designed. The first-stage sleeve is clearance-fitted with the valve core body. Combined with the fit between the plunger-type valve core and the flow orifice, when the medium passes through the regulating valve, a sealing surface is formed inside the first-stage sleeve, and throttling surfaces are formed at the second and third-stage sleeves. By separating the sealing surface and the throttling surface, the high-speed fluid at the throttling orifice impacts each other, and the energy is consumed within the fluid. This prevents the fluid from directly scouring the valve core body during impact, effectively extending the service life of the regulating valve. Simultaneously, the valve core uses a plunger-type design, which has excellent anti-cavitation capabilities. When the regulating valve opens, the impact energy is absorbed by the medium itself. Combined with the multi-layered sleeves, the kinetic energy of the medium is dissipated in the mutual impact, effectively reducing noise levels.

[0009] Furthermore, the height of the uppermost secondary throttling orifice of the secondary sleeve is higher than the height of the uppermost primary throttling orifice of the primary sleeve; the height of the lowermost secondary throttling orifice of the secondary sleeve is not lower than the height of the lowermost primary throttling orifice of the primary sleeve. This orifice height design ensures that when the regulating valve is open, the medium is located below the valve core body, preventing the impact energy of the medium from acting on the valve core and providing excellent anti-cavitation capabilities. Between the secondary and tertiary sleeves, a space is formed for high-speed fluid to counteract each other. This allows fluid to pass through while also suppressing and breaking up bubbles that may appear under certain operating conditions, reducing the damage of cavitation to the valve internals.

[0010] Furthermore, the secondary throttling orifice on the secondary sleeve and the tertiary throttling orifice on the tertiary sleeve are staggered. This staggered distribution of the throttling orifice can further effectively distribute the fluid, causing it to counteract energy loss. This allows the bubbles to be subjected to shear force and pressure changes in the early stages of formation, prompting the bubbles to break up prematurely. This prevents the bubbles from accumulating and breaking up in large quantities in the downstream area, further reducing the damage of cavitation to the valve internals.

[0011] Furthermore, the mounting hole is a three-stage variable diameter hole along the valve stem axial direction from top to bottom, namely an upper packing hole, a middle fitting hole, and a lower guide hole, wherein the middle fitting hole has a clearance fit with the valve stem.

[0012] Furthermore, the diameter of the upper packing hole is larger than the outer diameter of the valve stem. The inner wall of the upper packing hole is provided with a packing gland and a packing assembly from top to bottom. The packing assembly fills the space between the upper packing hole and the valve stem, and the packing gland presses the packing assembly downward to seal it, thus ensuring the sealing and dustproof capabilities of the control valve.

[0013] Furthermore, the lower guide hole diameter is larger than the valve stem outer diameter, and a guide sleeve is fixed to the inner wall of the guide hole. The inner diameter of the guide sleeve is adapted to the outer diameter of the valve stem. Through the design of the guide sleeve, the valve stem is provided with dual guidance, making the operation of the regulating valve safer and more reliable.

[0014] Preferably, the three-stage sleeve is a straight cylindrical structure, and the two-stage and one-stage sleeves are both I-beam structures, with the upper and lower ends of the I-beam structure abutting against the inner wall of the outer sleeve, respectively. Through the structural design and mutual cooperation of each stage of the sleeves, space is effectively formed for the flow and scouring of the medium, providing throttling and multi-stage pressure reduction for the medium flowing through each sleeve. This avoids rapid pressure changes and effectively reduces the possibility of vaporization due to sudden pressure drops, thereby reducing cavitation.

[0015] The beneficial effects of this utility model are that the multi-layer sleeve type pressure reducing and noise reducing regulating valve with plunger valve core provided by this utility model has a reasonable structural design. It adopts a design combination of plunger valve core and multi-layer sleeve, and the flow window is designed in the innermost layer of the sleeve. The harm of steam cavitation is dispersed to the sealing surface. In addition to the innermost first-stage sleeve as the flow window, there are also second-stage and third-stage sleeves after the valve, which fully reduces the damage of steam erosion and plays the role of pressure reducing and noise reducing. Attached Figure Description

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

[0017] Figure 1 This is a schematic diagram of the original double-guided cage-type single-seat regulating valve.

[0018] Figure 2 This is a schematic diagram of the preferred embodiment of the present invention.

[0019] Figure 3 This is a schematic diagram of the sleeve assembly in the preferred embodiment of this utility model.

[0020] Figure 4 This is a schematic diagram of the first-stage sleeve perforation profile of the preferred embodiment of this utility model.

[0021] In the figure: 1. Packing gland; 2. Packing assembly; 3. Upper valve cover; 4. First sealing gasket; 5. Guide sleeve; 6. Valve core body; 7. Flow hole; 8. Valve seat; 9. Second sealing gasket; 10. Valve body; 11. Inlet chamber; 12. Outlet chamber; 13. Valve stem; 14. First-stage sleeve; 15. First-stage throttling orifice; 16. Second-stage sleeve; 17. Second-stage throttling orifice; 18. Third-stage sleeve; 19. Third-stage throttling orifice. Detailed Implementation

[0022] The present invention will now be described in further detail with reference to the accompanying drawings. These drawings are simplified schematic diagrams, illustrating only the basic structure of the present invention. Therefore, they only show the components relevant to the present invention. Orientations and references (e.g., up, down, left, right, etc.) are only used to aid in the description of the features in the drawings. Therefore, the following specific embodiments are not intended to be restrictive, and the scope of the claimed subject matter is defined solely by the appended claims and their equivalents.

[0023] like Figure 2 The multi-layer sleeve-type pressure-reducing and noise-reducing regulating valve with a plunger valve core shown is the preferred embodiment of this utility model.

[0024] The regulating valve includes an upper valve cover 3, a valve body 10, a valve seat 8, a valve core assembly, and a sleeve assembly. The valve body 10 has a medium inlet on the left and a medium outlet on the right. The valve body 10 is internally divided into an inlet cavity 11 and an outlet cavity 12. The inlet cavity 11 communicates with the medium inlet of the valve body 10, and the outlet cavity 12 communicates with the medium outlet of the valve body 10. The valve seat 8 is fixed inside the valve body 10 and located at the separation position between the inlet cavity 11 and the outlet cavity 12. A first sealing gasket 4 can be designed at the fixed end face of the valve seat 8 and the valve body 10 to enhance the sealing effect. The upper valve cover 3 is fixed to the upper end of the valve body 10. A second sealing gasket 9 can be designed between the upper valve cover 3 and the upper end of the valve body 10 to enhance the sealing effect. A through mounting hole is provided on the upper valve cover 3, and a corresponding hole communicating with the outlet cavity 12 is provided on the valve body 10 at the mounting position of the upper valve cover 3.

[0025] The valve core assembly includes a valve core body 6 and a valve stem 13. The valve stem 13 extends through the mounting hole and into the outlet cavity 12 of the valve body 10, while the valve core body 6 is fixed to the lower end of the valve stem 13. In this embodiment, when a plunger-type valve core is selected for the valve core body 6, the valve stem 13 can be directly integrated into its upper end, that is, the valve stem 13 and the valve core body 6 adopt an integral structure. The valve seat 8 has a flow hole 7 that connects the inlet cavity 11 and the outlet cavity 12, and the lower end of the valve core body 6 is adapted to the flow hole 7; as the valve core body 6 rises with the valve stem 13 away from the flow hole 7, the inlet cavity 11 and the outlet cavity 12 are connected; as the valve core body 6 descends with the valve stem 13 and abuts against the flow hole 7, the inlet cavity 11 and the outlet cavity 12 are blocked.

[0026] In this embodiment, the optimal choice for the valve core body 6 is a plunger-type valve core. Compared to perforated valve cores, plunger-type valve cores offer faster opening and closing response, better sealing, and easier manufacturing. The plunger sealing surface typically possesses high strength and rigidity, capable of withstanding the erosion of high-speed fluids and particulate media. The valve seat 8 is made of 316 austenitic stainless steel, and its sealing surface is overlaid with Stellite welding, achieving a hardness of HRC40-45. The valve core body 6 is also made of 316 austenitic stainless steel and undergoes overall nitriding treatment, effectively improving the surface hardness of the valve core. The nitrided layer hardness is >1000HV1, thus enhancing the overall erosion resistance of the cage-type valve seat 8 and the valve core, extending the valve's service life.

[0027] In the fit between valve stem 13 and upper valve cover 3 and valve body 10, the mounting hole is a three-stage variable diameter hole along the axial direction of valve stem 13 from top to bottom, namely upper packing hole, middle fitting hole and lower guide hole, and the middle fitting hole is clearance fit with valve stem 13.

[0028] At the upper packing hole position, the sealing and dustproof capabilities of the control valve are ensured: the diameter of the upper packing hole is larger than the outer diameter of the valve stem 13, and the inner wall of the upper packing hole is provided with a packing gland 1 and a packing assembly 2 from top to bottom. The packing assembly 2 fills between the upper packing hole and the valve stem 13, and the packing gland 1 presses the packing assembly 2 downward to seal it.

[0029] At the lower guide hole position, the upper guiding effect of the control valve is ensured: the diameter of the lower guide hole is larger than the outer diameter of the valve stem 13, and a guide sleeve 5 is fixed on the inner wall of the guide hole. The inner diameter of the guide sleeve 5 is adapted to the outer diameter of the valve stem 13. Through the design of the guide sleeve 5, the valve stem 13 is provided with double guidance, making the operation of the control valve safer and more reliable.

[0030] like Figure 2 and Figure 3 As shown, the sleeve assembly is supported between the upper valve cover 3 and the valve seat 8, including a primary sleeve 14, a secondary sleeve 16, and a tertiary sleeve 18 concentrically distributed from the inside out. The tertiary sleeve 18 has a straight cylindrical structure, while the secondary sleeve 16 and the primary sleeve 14 are both I-beam structures, with their upper and lower ends abutting against the inner walls of their outer sleeves. Each sleeve can be selected according to the valve's operating conditions, and the size and distribution density of the throttling orifice can be adjusted accordingly during assembly. After selecting each sleeve, they are assembled and welded together. Through the structural design and mutual cooperation of each sleeve, a space for media flow and scouring is effectively formed, providing throttling and multi-stage pressure reduction space for the media flowing through each sleeve. This avoids rapid pressure changes and effectively reduces the possibility of vaporization due to sudden pressure drops, thereby reducing cavitation.

[0031] Specifically, the inner diameter of the first-stage sleeve 14 is adapted to the outer diameter of the valve core body 6, and the inner wall of the first-stage sleeve 14 is clearance-fitted with the outer wall of the valve core. Several first-stage throttling orifices 15 are staggered on the side wall of the first-stage sleeve 14 near the valve seat 8. Several second-stage throttling orifices 17 are staggered on the wall of the second-stage sleeve 16. Several third-stage throttling orifices 19 are staggered on the wall of the third-stage sleeve 18. For each sleeve, the profile design adopts the following... Figure 4 The design shown is a centrally symmetrical, circumferentially evenly distributed perforated window.

[0032] The secondary throttling orifice 17 on the secondary sleeve 16 and the tertiary throttling orifice 19 on the tertiary sleeve 18 are staggered. The staggered distribution of the throttling orifices can further effectively distribute the fluid, causing it to offset energy consumption. This allows the bubbles to be subjected to shear force and pressure changes in the early stage of formation, prompting the bubbles to break up in advance and preventing the bubbles from accumulating and breaking up in large quantities in the downstream area, thus further reducing the damage of cavitation to the valve internals.

[0033] The height of the uppermost secondary throttling orifice 17 on the secondary sleeve 16 is higher than the height of the uppermost primary throttling orifice 15 on the primary sleeve 14; the height of the lowermost secondary throttling orifice 17 on the secondary sleeve 16 is not lower than the height of the lowermost primary throttling orifice 15 on the primary sleeve 14. This orifice height design ensures that when the control valve is open, the medium is located below the valve core body 6, preventing the impact energy of the medium from acting on the valve core and providing excellent anti-cavitation capabilities. Between the secondary sleeve 16 and the tertiary sleeve 18, a space is formed for high-speed fluid to counteract each other. This allows fluid to pass through while also suppressing and breaking up bubbles that may appear under certain operating conditions, reducing the damage of cavitation to the valve internals.

[0034] In actual drilling profile design, the first-stage throttling orifice 15 on the first-stage sleeve 14, such as Figure 4 As shown, the orifice diameter gradually increases from bottom to top along the axial direction of the valve core assembly. This gradual increase in diameter is designed to further reduce the erosion of the valve core assembly caused by excessive flow at the sealing surface. The throttling orifices on the secondary sleeve 16 and the tertiary sleeve 18 can be designed with equal diameters. The only difference is that the throttling orifices on the two sleeves are staggered in position, which further enhances the energy dissipation of the counter-current flow between the two sleeves.

[0035] Through the above-described multi-stage sleeve design, combined with the opening and closing of the plunger-type valve core, this embodiment achieves the following design advantages: 1. Good resistance to cavitation (1) Reasonable flow channel design: The perforation surface design of the sleeve adopts a centrally symmetrical, circumferentially evenly distributed perforated window design, which has a flow rectification effect. When the fluid passes through, it can maintain a relatively smooth flow state, reduce local eddies and sudden changes in flow velocity, and help avoid the generation of excessively low pressure areas inside the valve, thereby reducing the possibility of cavitation.

[0036] (2) Bubble suppression and breakup: Even if bubbles appear under certain operating conditions, the cage structure formed by the multi-layer sleeve can suppress and break up the bubbles to a certain extent. The throttling window and flow channel in the cage structure can subject the bubbles to shear force and pressure changes in the early stage of formation, prompting the bubbles to break up in advance, avoiding the large accumulation and rupture of bubbles in the downstream area, thereby reducing the damage of cavitation to valve internals.

[0037] 2. Enhanced resistance to erosion

[0038] (1) Uniform fluid distribution: The perforated surface of the sleeve enables the fluid to be evenly distributed inside the valve, avoiding localized concentrated scouring of the valve internals by the fluid. Multiple throttling windows, i.e., throttling orifices at various levels, enable the fluid to form multiple uniform flow streams when passing through the valve. These flow streams interact with each other, making the fluid energy more dispersed and reducing the scouring force on individual parts.

[0039] (2) Robust Structural Design: The sealing surface of the plunger-type valve core typically possesses high strength and rigidity, capable of withstanding the erosion of high-speed fluids and particulate media. The valve seat 8 is made of 316 austenitic stainless steel, and the sealing surface of the valve seat 8 is overlaid with Stellite welding, achieving a hardness of HRC40-45. The valve core is also made of 316 austenitic stainless steel and undergoes overall nitriding treatment, effectively improving the surface hardness of the valve core; the nitrided layer hardness is >1000HV1. This enhances the overall erosion resistance of the cage-type valve seat 8 and the valve core, extending the valve's service life.

[0040] (3) Multi-stage pressure reduction: The multi-layer sleeve achieves multi-stage pressure reduction through multiple throttling stages, so that the pressure of the fluid gradually decreases as it passes through the valve. This gradual pressure reduction method avoids drastic pressure changes and effectively reduces the possibility of vaporization of the fluid due to sudden pressure drops, thereby reducing the occurrence of cavitation.

[0041] 3. The plunger valve core can respond quickly to opening and closing, has good sealing performance, and is easy to process.

[0042] 4. Replaceable flow window sleeve, which throttles flow, reduces pressure, and reduces noise.

[0043] 5. In the cooperation between the upper valve cover 3 and the valve stem 13, a guide sleeve 5 is used to give the valve core, i.e. the valve stem 13, a double guide design, making the operation more stable, safe and reliable.

[0044] 6. In the connection of various components, packing, gaskets, dust rings and other structures are used in combination to ensure the valve's sealing performance and dustproof capability.

[0045] Based on the above-described preferred embodiments of this utility model, and through the foregoing description, those skilled in the art can make various changes and modifications without departing from the technical concept of this utility model. The technical scope of this utility model is not limited to the contents of the specification, but must be determined according to the scope of the claims.

Claims

1. A multi-layer sleeve-type pressure-reducing and noise-reducing regulating valve with a plunger valve core, comprising an upper valve cover, a valve body, a valve seat, and a valve core assembly, wherein the valve body is divided into an inlet chamber and an outlet chamber, the inlet chamber being connected to the medium inlet of the valve body, and the outlet chamber being connected to the medium outlet of the valve body, and the valve seat being fixed inside the valve body and located at the separation position between the inlet chamber and the outlet chamber, characterized in that: The valve core assembly includes a valve core body and a valve stem. The upper valve cover has a through mounting hole. The valve stem passes through the mounting hole and extends into the outlet cavity of the valve body. The valve core body is fixed to the lower end of the valve stem. The valve core body is a plunger-type valve core. The valve seat has a flow hole that connects the inlet cavity and the outlet cavity. The lower end of the valve core body is adapted to the flow hole. As the valve stem rises, the valve core body moves away from the flow hole, and the inlet cavity and the outlet cavity are connected. As the valve stem descends, the valve core body abuts against the flow hole, and the inlet cavity and the outlet cavity are blocked. Includes a sleeve assembly, which is supported and disposed between the upper valve cover and the valve seat; The sleeve assembly includes a primary sleeve, a secondary sleeve, and a tertiary sleeve concentrically distributed from the inside to the outside. The inner diameter of the primary sleeve is adapted to the outer diameter of the valve core body, and the inner wall of the primary sleeve is clearance-fitted with the outer wall of the valve core. Several primary throttling holes are staggered on the side wall of the primary sleeve near the valve seat. The secondary sleeve has several secondary throttling holes distributed irregularly on its cylinder wall; the tertiary sleeve has several tertiary throttling holes distributed irregularly on its cylinder wall.

2. The multi-layer sleeve-type pressure-reducing and noise-reducing regulating valve with a plunger valve core as described in claim 1, characterized in that: The height of the uppermost secondary throttling orifice of the secondary sleeve is higher than the height of the uppermost primary throttling orifice of the primary sleeve; the height of the lowermost secondary throttling orifice of the secondary sleeve is not lower than the height of the lowermost primary throttling orifice of the primary sleeve.

3. The multi-layer sleeve-type pressure-reducing and noise-reducing regulating valve with a plunger valve core as described in claim 2, characterized in that: The secondary throttling orifice on the secondary sleeve and the tertiary throttling orifice on the tertiary sleeve are misaligned.

4. The multi-layer sleeve-type pressure-reducing and noise-reducing regulating valve with a plunger valve core as described in claim 1, characterized in that: The mounting holes are three-stage variable diameter holes along the valve stem axial direction from top to bottom: upper packing hole, middle fitting hole, and lower guide hole. The middle fitting hole has a clearance fit with the valve stem.

5. A multi-layer sleeve-type pressure-reducing and noise-reducing regulating valve with a plunger valve core as described in claim 4, characterized in that: The upper packing hole has a diameter larger than the outer diameter of the valve stem. The inner wall of the upper packing hole is provided with a packing gland and a packing assembly from top to bottom. The packing assembly fills the space between the upper packing hole and the valve stem, and the packing gland presses the packing assembly downward to seal it.

6. A multi-layer sleeve-type pressure-reducing and noise-reducing regulating valve with a plunger valve core as described in claim 4, characterized in that: The lower guide hole has a diameter larger than the outer diameter of the valve stem, and a guide sleeve is fixed to the inner wall of the guide hole. The inner diameter of the guide sleeve is adapted to the outer diameter of the valve stem.

7. A multi-layer sleeve-type pressure-reducing and noise-reducing regulating valve with a plunger valve core as described in claim 1, characterized in that: The three-stage sleeve is a straight cylindrical structure, and the two-stage sleeve and the one-stage sleeve are both I-beam structures, with the upper and lower ends of the I-beam structure respectively abutting against the inner wall of the outer sleeve.

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