A multi-stage pressure reducing regulating valve

Abstract

The application relates to the technical field of regulating valves, in particular to a multistage pressure-reducing regulating valve, which comprises a valve body and a valve cover installed above the valve body, a valve seat is installed in the middle of the valve body, a valve cage is connected above the valve seat, a valve core is arranged in the valve cage, the lower end of a valve rod is connected with an installation hole arranged in the upper middle part of the valve core through a pin, flow-through holes are arranged at equal intervals on the upper outer side surface of the valve cage, a pressure-reducing groove is arranged on the inner side of the valve cage, a throttling groove is arranged on the outer side surface of the valve core, and a porous plate is fixed in the throttling groove. The multistage pressure-reducing regulating valve can further reduce the pressure of fluid through the porous plate, can reduce the risk of cavitation in the local low-pressure area by dispersing the pressure drop, can avoid the direct impact of high-speed fluid jet on the upper inclined surface of the throttling groove, can greatly reduce the impact force, can protect the throttling groove, can avoid damage to the valve core, and can prolong the service life of the whole multistage pressure-reducing regulating valve.

Description

Technical Field

[0001] This invention relates to the field of regulating valve technology, specifically a multi-stage pressure reducing regulating valve. Background Technology

[0002] Multistage pressure reducing regulating valves are industrial control valves specifically designed for high pressure differential conditions. Through their internal multistage throttling structure, they decompose the total pressure differential into multiple smaller pressure differentials, thereby suppressing cavitation, flashing, vibration, and noise, and achieving precise and stable regulation of fluid pressure and flow. Therefore, multistage pressure reducing regulating valves are widely used in industries such as petroleum, chemical, and pharmaceutical to ensure the safety and stability of production. For example, the patent disclosed in the prior art with publication number "CN206309972U" is entitled "A Cascade Multi-Stage Pressure Reduction Differential Pressure Regulating Valve". It discloses that the valve cage is a tubular body with three annular protrusions on the inner wall of the valve cage. Four through holes are evenly distributed circumferentially on the inner wall of the tube above the first annular protrusion. The valve core is a cylindrical body with a groove on the upper surface of the outer surface of the valve core. Three pairs of flat grooves are provided on the outer surface of the valve core below the groove. The upper and lower pairs of flat grooves are horizontally aligned with the outer surface of the vertical body. The valve is designed with a pair of horizontal grooves arranged longitudinally along the outside of the vertical body. The fluid is throttled by the horizontal groove steps of the multi-stage valve core, causing the high-pressure fluid to flow in a curved manner along the valve core axis. The fluid continuously turns and collides through the flow area formed between the valve core and the valve cage. By adopting a design method that combines radial and axial flow, the high pressure difference of the medium continuously decreases along the valve core axis, effectively controlling the pressure drop and flow rate of the fluid, preventing flashing and cavitation, and improving the service life of the control valve under harsh operating conditions.

[0003] In the existing multi-stage pressure reducing regulating valve, although the inclined surface above the groove can disperse the high-speed jet of the fluid after each throttling stage and prevent the high-speed jet from directly scouring the valve core of the next stage, the high jet velocity and impact force of the fluid will damage the inclined surface above the groove after long-term use, which will then lead to damage to the valve core, thus reducing the service life of the entire multi-stage pressure reducing regulating valve. Therefore, we propose a multi-stage pressure reducing regulating valve to solve the problems mentioned above. Summary of the Invention

[0004] The purpose of this invention is to provide a multi-stage pressure reducing regulating valve to solve the problem mentioned in the background art. In existing multi-stage pressure reducing regulating valves, although the inclined surface above the flat groove can disperse the high-speed jet of the fluid after each throttling stage and prevent the high-speed jet from directly scouring the valve core of the next stage, the high jet velocity and impact force of the fluid will damage the inclined surface above the flat groove after long-term use, which in turn will damage the valve core, thus reducing the service life of the entire multi-stage pressure reducing regulating valve.

[0005] To achieve the above objectives, the present invention provides the following technical solution: a multi-stage pressure reducing regulating valve, comprising a valve body and a valve cover mounted on it, a packing gland mounted on the valve cover, a valve stem slidably penetrating the interior of both the valve cover and the packing gland, a valve seat mounted in the middle of the valve body, a valve cage connected above the valve seat, a valve core disposed inside the valve cage, the lower end of the valve stem connected to an mounting hole opened in the middle of the upper part of the valve core by a pin, flow holes equally spaced on the upper outer side of the valve cage, a pressure reducing groove opened on the inner side of the valve cage, a throttling groove opened on the outer side of the valve core, and a perforated plate fixed inside the throttling groove.

[0006] Preferably, the valve body has an inlet and an outlet on the left and right sides respectively. The valve body and the valve cover, as well as the valve cover and the packing gland, are connected by studs. Two sets of studs are provided, and nuts are installed on the outside of the studs.

[0007] Preferably, the top of the valve stem is connected to an external actuator, and a packing assembly is installed in the space between the valve stem and the valve cover.

[0008] Preferably, the bottom surface of the valve seat is sealed and fixedly connected to the middle inner wall of the valve body through a gasket, the bottom surface of the valve cover is connected to the top of the valve cage through a gasket, the bottom surface of the valve cage is connected to the upper surface of the valve seat through a gasket, three sets of gaskets are provided, the gaskets are made of flexible graphite, and the outer side of the bottom surface of the valve core is connected to the inner side wall of the valve seat by a conical hard seal.

[0009] Preferably, the valve core has a Y-shaped balance hole inside, a support ring is installed on the upper outer side of the valve core, an anti-compression ring is installed below the support ring, and a spring-loaded sealing ring is installed below the anti-compression ring. The outer side of the spring-loaded sealing ring is in sealed contact with the inner wall of the valve cage.

[0010] Preferably, the pressure-reducing groove is arranged in a ring shape, with both the upper and lower surfaces of the pressure-reducing groove being inclined. The depth of the pressure-reducing groove is less than the wall thickness of the valve cage, the depth of the flow hole is equal to the wall thickness of the valve cage, and a pressure-reducing groove is provided below the flow hole. There is a gap between the pressure-reducing groove and the interior of the valve body.

[0011] Preferably, the valve core has a circular annular groove on its upper outer side, the groove being located above the throttling groove, and two adjacent sets of throttling grooves being staggered. The throttling groove has a U-shaped cross-section and its upper surface is an inclined surface with rounded corners.

[0012] Preferably, the outer surface of the perforated plate is arc-shaped, and there is a gap between the outer surface of the perforated plate and the inner wall of the valve cage.

[0013] Preferably, a sealing cover is installed on the upper surface of the valve core with a sealing screw. The upper inner diameter of the sealing cover is smaller than the lower inner diameter of the sealing cover, and the lower inner diameter of the sealing cover is larger than the diameter of the mounting hole opened in the middle of the upper part of the valve core. A valve stem is provided through the upper interior of the sealing cover. A sealing ring installed inside the upper interior of the sealing cover is in sealing contact with the outer side of the valve stem. Two vertical rods are symmetrically installed on the inner side wall of the sealing cover. The vertical rods are inserted into the mounting hole opened in the middle of the upper part of the valve core.

[0014] Preferably, a sealing disc is installed at the bottom end of the valve stem, and a sealing gasket installed on the bottom surface of the sealing disc seals and fits in contact with the inner wall of the mounting hole opened in the middle of the upper part of the valve core. Pressure sensors are symmetrically installed on the upper surface of the sealing disc, and there is a gap between the lower end of the vertical rod and the pressure sensor.

[0015] Compared with the prior art, the beneficial effects of the present invention are as follows: This multi-stage pressure reducing regulating valve, with its orifice plate, can not only further reduce the pressure of the fluid, but also reduce the risk of cavitation in local low-pressure areas by dispersing the pressure drop through the orifice plate. Furthermore, it can prevent the high-speed fluid jet from directly impacting the inclined surface above the throttling groove, significantly reducing the impact force and facilitating the protection of the throttling groove, thus preventing damage to the valve core and improving the service life of the entire multi-stage pressure reducing regulating valve. Simultaneously, it can eliminate the pulsation source that excites valve core vibration, reducing noise during operation. The specific details are as follows: (1) By installing a perforated plate inside the throttling groove, when the fluid passes through the perforated plate, the jet cross section generated by each small hole in the perforated plate is small and the flow rate is small. As a result, the perforated plate disperses the concentrated jet of the fluid into multiple small jets. By utilizing mutual interference and energy dissipation, the jet velocity and impact force of the fluid are effectively reduced. This allows the perforated plate to not only further reduce the pressure of the fluid, but also reduce the risk of cavitation in the local low-pressure area by dispersing the pressure drop through the perforated plate. It also prevents the high-speed jet of the fluid from directly impacting the inclined surface above the throttling groove, greatly reducing the impact force and facilitating the protection of the throttling groove. This prevents damage to the valve core and thus improves the service life of the entire multi-stage pressure reducing regulating valve. At the same time, it can eliminate the pulsation source that excites the vibration of the valve core and reduce the noise during operation. (2) The upper and lower surfaces of the pressure reducing tank are designed as inclined surfaces. This not only avoids the problem of slag accumulation in the existing horizontal area, but also disperses the high-speed jet of the fluid after each throttling stage by setting the inclined surface, preventing the jet from directly scouring the next stage valve core, thereby further improving the service life of the valve core. (3) When the valve core is subjected to huge axial force under high pressure differential, causing the pin to fatigue and break, the valve core moves downward by its own weight. The valve core drives the sealing cover and the vertical rod to move downward together. At this time, the sealing cover slides downward on the outside of the valve rod. When the bottom end of the vertical rod descends to contact the pressure sensor on the sealing plate, the vertical rod applies pressure to the pressure sensor. In this way, the sealing plate blocks the vertical rod, so that the maximum stroke of the valve core is only 2mm-5mm, which is far less than the displacement required for the valve core to directly hit the valve seat below. This not only avoids the valve core and valve rod from completely falling off, which would cause a large impact force between the bottom of the valve core and the valve seat below, but also, after the pressure sensor detects the pressure, the pressure sensor transmits the signal to the PLC controller in the regulating valve. The PLC controller controls the alarm installed on the outside of the regulating valve to automatically sound an alarm, which makes it easy to detect the pin damage in time and the staff can discover the alarm in time. Attached Figure Description

[0016] Figure 1 This is a three-dimensional structural diagram of the present invention; Figure 2 This is a schematic diagram of the main cross-sectional structure of the valve body of the present invention; Figure 3 For the present invention Figure 2 Enlarged structural diagram at point A in the middle; Figure 4 This is a schematic diagram of the main cross-sectional structure of the valve cage of the present invention; Figure 5 This is a schematic diagram of the three-dimensional structure of the valve core of the present invention; Figure 6 This is a schematic diagram of the main cross-sectional structure of the valve core of the present invention; Figure 7 This is a schematic diagram of the three-dimensional structure of the valve core in Embodiment 2 of the present invention; Figure 8 This is a schematic diagram of the main cross-sectional structure of the connection between the valve core and the valve stem in Embodiment 2 of the present invention; Figure 9 For the present invention Figure 8 Enlarged structural diagram at point B.

[0017] In the diagram: 1. Valve body; 101. Inlet; 102. Outlet; 2. Valve cover; 3. Packing gland; 4. Stud; 5. Valve stem; 6. Packing assembly; 7. Valve cage; 71. Flow hole; 72. Pressure relief groove; 8. Valve seat; 9. Valve core; 91. Throttling groove; 92. Manifold groove; 93. Y-shaped balance hole; 10. Perforated plate; 11. Support ring; 12. Anti-extrusion ring; 13. Spring-loaded sealing ring; 14. Sealing cover; 141. Vertical rod; 15. Sealing disc; 151. Pressure sensor. Detailed Implementation

[0018] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0019] Please see Figures 1-9 The present invention provides the following technical solution: Example 1: The multi-stage pressure reducing regulating valve in this example avoids the high-speed fluid jet directly impacting the inclined surface above the throttling groove 91, significantly reducing the impact force and facilitating the protection of the throttling groove 91, preventing damage to the valve core 9, thereby improving the service life of the entire multi-stage pressure reducing regulating valve. For the specific structure, please refer to the attached diagram. Figures 1-6 As shown, the valve includes a valve body 1 and a valve cover 2 mounted on top of it. A packing gland 3 is installed on top of the valve cover 2. A valve stem 5 slides through the interior of both the valve cover 2 and the packing gland 3. A valve seat 8 is installed in the middle of the valve body 1. A valve cage 7 is connected above the valve seat 8. A valve core 9 is installed inside the valve cage 7. The lower end of the valve stem 5 is connected to the mounting hole in the middle of the upper part of the valve core 9 by a pin. The top end of the valve stem 5 is connected to an external actuator.

[0020] The specific structure of the above technical solution is shown in the appendix. Figures 1-6 As shown, the top of the valve stem 5 is first connected to the output end of the external actuator through a nut. Then, the actuator automatically controls the valve stem 5 to rise or fall by receiving signals from the control system, thereby achieving precise control of the regulating valve. Since this part is existing technology, it will not be described in detail here, nor is the actuator shown in the attached figure.

[0021] In a preferred embodiment of the present invention, a packing assembly 6 is installed in the space between the valve stem 5 and the valve cover 2.

[0022] In the above technical solution, when the valve stem 5 drives the valve core 9 to move upward, the upper end of the valve stem 5 slides through the valve cover 2 and the packing gland 3 in a sealed manner. The packing assembly 6 in the valve cover 2 can be made of polytetrafluoroethylene packing.

[0023] In a preferred embodiment of the present invention, the valve cage 7 has flow holes 71 evenly spaced on its upper outer side, a pressure reducing groove 72 is provided on the inner side of the valve cage 7, a throttling groove 91 is provided on the outer side of the valve core 9, and an inlet 101 and an outlet 102 are respectively provided on the left and right sides of the valve body 1. The valve body 1 and the valve cover 2, as well as the valve cover 2 and the packing gland 3, are connected by studs 4. Two sets of studs 4 are provided, and nuts are installed on the outer side of the studs 4. The bottom surface of the valve seat 8 is sealed and fixedly connected to the middle inner wall of the valve body 1 by a gasket. The bottom surface of the valve cover 2 is connected to the upper part of the valve cage 7 by a gasket. The bottom surface of the valve cage 7 is connected to the upper surface of the valve seat 8 by a gasket. Three sets of gaskets are provided. The gaskets are made of flexible graphite. The outer side of the bottom surface of the valve core 9 and the inner side wall of the valve seat 8 are connected by a conical hard seal.

[0024] In the above technical solution, when the valve core 9 moves upward, the bottom surface of the valve core 9 separates from the valve seat 8, and the annular confluence groove 92 rises to the position corresponding to the flow hole 71. At this time, the fluid enters the valve body 1 through the inlet 101, and then the fluid in the inlet 101 flows upward through the gap between the hollow valve seat 8 and the valve core 9. Then the fluid flows into the throttling groove 91 opened on the outside of the valve core 9 for throttling.

[0025] In a preferred embodiment of the present invention, a circular annular groove 92 is provided on the upper outer side of the valve core 9. The groove 92 is located above the throttling groove 91. Two adjacent sets of throttling grooves 91 are staggered. The cross-section of the throttling groove 91 is U-shaped, and the upper surface of the throttling groove 91 is an inclined surface with rounded corners.

[0026] In the above technical solution, since the two adjacent sets of throttling grooves 91 are staggered, the fluid in the lower throttling groove 91 is throttled and then flows to the upper throttling groove 91 through the corresponding annular pressure-reducing groove 72 on the outer side. This causes the high-pressure fluid to bend and flow upward along the axial direction of the valve core 9. Therefore, the high-pressure fluid is forced to continuously turn and collide within the flow channel formed between the throttling groove 91 on the outer side of the valve core 9 and the pressure-reducing groove 72 on the inner side of the valve cage 7. This design combines radial and axial flow characteristics. The method causes the high pressure differential of the fluid to continuously decrease along the axial direction of the valve core 9, so that the total pressure drop is distributed in several stages, ensuring that the pressure drop of each stage is below the critical value for cavitation, effectively controlling the pressure drop and flow rate of the fluid, preventing the fluid from flashing and cavitation, and improving the service life of the control valve under harsh operating conditions. Then the fluid flows upward into the annular-shaped manifold groove 92, and then the fluid in the manifold groove 92 flows through the flow hole 71 into the space between the outside of the valve cage 7 and the inside of the valve body 1, and then the fluid is discharged through the outlet 102.

[0027] In a preferred embodiment of the present invention, a perforated plate 10 is fixed inside the throttling groove 91.

[0028] In the above technical solution, simultaneously, when the fluid flows into the throttling groove 91 opened on the outside of the valve core 9 for throttling, when the fluid passes through the perforated plate 10 installed inside the throttling groove 91, because the jet cross-section and flow rate generated by each small hole in the perforated plate 10 are small, the perforated plate 10 disperses the concentrated jet of fluid into multiple small jets. By utilizing mutual interference and energy dissipation, it effectively reduces the jet velocity and impact force of the fluid. This allows the perforated plate 10 to not only further reduce the pressure of the fluid, but also, by dispersing the pressure drop, reduce the local pressure. This reduces the risk of cavitation in the low-pressure area and also prevents high-speed fluid jets from directly impacting the inclined surface above the throttling groove 91, significantly reducing the impact force and facilitating the protection of the throttling groove 91. This prevents damage to the valve core 9, thereby increasing the service life of the entire multi-stage pressure reducing regulating valve. At the same time, it can eliminate the pulsation source that excites the vibration of the valve core 9, reducing operating noise. The key internal components such as the valve core 9, valve cage 7, and perforated plate 10 can be made of stainless steel, which can improve erosion resistance. The perforated plate 10 can be installed inside the throttling groove 91 by welding or screws.

[0029] In a preferred embodiment of the present invention, the outer side of the perforated plate 10 is arc-shaped, and there is a gap between the outer side of the perforated plate 10 and the inner wall of the valve cage 7.

[0030] In the above technical solution, when the valve core 9 moves upward, the outer side of the perforated plate 10 will not contact the inner wall of the valve cage 7, thereby avoiding friction.

[0031] In a preferred embodiment of the present invention, the pressure reducing groove 72 is arranged in a ring shape, and both the upper and lower surfaces of the pressure reducing groove 72 are inclined surfaces. The depth of the pressure reducing groove 72 is less than the wall thickness of the valve cage 7, the depth of the flow hole 71 is equal to the wall thickness of the valve cage 7, and the pressure reducing groove 72 is arranged below the flow hole 71. There is a gap between the pressure reducing groove 72 and the interior of the valve body 1.

[0032] In the above technical solution, when the fluid flows into the pressure reducing tank 72, since the upper and lower surfaces of the pressure reducing tank 72 are both designed as inclined surfaces, this not only avoids the problem of slag accumulation in the existing horizontal area, but also disperses the high-speed jet of the fluid after each stage of throttling by setting the inclined surface, preventing the jet from directly scouring the next stage valve core 9, thereby further improving the service life of the valve core 9.

[0033] In a preferred embodiment of the present invention, a Y-shaped balance hole 93 is provided inside the valve core 9.

[0034] In the above technical solution, when the regulating valve is closed, the upper outer side of the valve core 9 is sealed to the inner wall of the valve cage 7, and the lower outer side of the valve core 9 is sealed to the inner wall of the valve seat 8, so that the fluid cannot flow into the throttling groove 91 and the pressure reducing groove 72. At this time, through the setting of the Y-shaped balance hole 93, the fluid entering the inlet 101 can be evenly entered into the cavity at the top of the valve core 9 through the Y-shaped balance hole 93. Therefore, when the valve stem 5 pushes the valve core 9 downward, the thrust and resistance can be reduced, so that the valve core 9 moves downward stably and avoids excessive pressure at the lower inlet, which would lead to poor sealing.

[0035] In a preferred embodiment of the present invention, a support ring 11 is installed on the upper outer side of the valve core 9, an anti-compression ring 12 is installed below the support ring 11, and a spring-loaded sealing ring 13 is installed below the anti-compression ring 12. The outer side of the spring-loaded sealing ring 13 is in sealing contact with the inner wall of the valve cage 7.

[0036] In the above technical solution, the cooperation of the support ring 11, the anti-compression ring 12, and the spring-loaded sealing ring 13 can ensure the sealing between the upper outer side of the valve core 9 and the inner wall of the valve cage 7 when the valve core 9 is raised and lowered.

[0037] Example 2: The multi-stage pressure reducing regulating valve in this example, based on Example 1, not only prevents the valve core 9 from completely separating from the valve stem 5 when the pin fractures due to fatigue, but also provides timely warning, facilitating timely maintenance by staff. See attached diagram for the specific structure. Figures 7-9 As shown.

[0038] In a preferred embodiment of the present invention, a sealing cover 14 is installed on the upper surface of the valve core 9 by a sealing screw. The upper inner diameter of the sealing cover 14 is smaller than the lower inner diameter of the sealing cover 14, and the lower inner diameter of the sealing cover 14 is larger than the diameter of the mounting hole opened in the middle of the upper part of the valve core 9. A valve stem 5 is provided through the upper interior of the sealing cover 14. A sealing ring installed inside the upper interior of the sealing cover 14 is in sealing contact with the outer side of the valve stem 5. Two vertical rods 141 are symmetrically installed on the inner sidewall of the sealing cover 14. The vertical rods 141 are inserted into the mounting hole opened in the middle of the upper part of the valve core 9. A sealing disc 15 is installed at the bottom end of the valve stem 5. A sealing gasket installed on the bottom surface of the sealing disc 15 is in sealing contact with the inner sidewall of the mounting hole opened in the middle of the upper part of the valve core 9. A pressure sensor 151 is symmetrically installed on the upper surface of the sealing disc 15. There is a gap between the lower end of the vertical rod 141 and the pressure sensor 151.

[0039] In the above technical solution, when the valve core 9 is subjected to a huge axial force under high pressure differential, causing the pin at the connection between the valve core 9 and the valve stem 5 to fatigue and break, the valve core 9 moves downward by its own gravity. The valve core 9 drives the sealing cover 14 and the vertical rod 141 to move downward together. At this time, the sealing cover 14, in conjunction with the sealing ring installed on the inner side above, slides downward to seal the valve stem 5 on the outer side. When the bottom end of the vertical rod 141 descends to contact the pressure sensor 151 on the sealing disc 15, the vertical rod 141 applies pressure to the pressure sensor 151. In this way, the sealing disc 15 applies pressure to the vertical rod 141. The obstruction of 41 ensures that the maximum downward stroke of the valve core 9 is only 2mm-5mm, which is far less than the displacement required for the valve core 9 to directly impact the valve seat 8 below. This not only prevents the valve core 9 from completely detaching from the valve stem 5, thus avoiding a large impact force between the bottom of the valve core 9 and the valve seat 8 below, but also allows the pressure sensor 151 to detect pressure and transmit the signal to the PLC controller inside the regulating valve. The PLC controller then controls the alarm installed on the outside of the regulating valve to automatically sound an alarm, facilitating timely detection of pin damage and allowing staff to promptly discover the alarm.

[0040] Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of the technical features. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A multi-stage pressure reducing regulating valve, comprising a valve body (1) and a valve cover (2) mounted thereon, wherein a packing gland (3) is mounted above the valve cover (2), characterized in that: The valve stem (5) slides through the interior of both the valve cover (2) and the packing gland (3). A valve seat (8) is installed in the middle of the valve body (1). A valve cage (7) is connected above the valve seat (8). A valve core (9) is installed inside the valve cage (7). The lower end of the valve stem (5) is connected to the mounting hole in the middle of the upper part of the valve core (9) by a pin. Flow holes (71) are opened at equal intervals on the upper outer side of the valve cage (7). A pressure reducing groove (72) is opened on the inner side of the valve cage (7). A throttling groove (91) is opened on the outer side of the valve core (9). A perforated plate (10) is fixed inside the throttling groove (91). A sealing cover (14) is installed on the upper surface of the valve core (9) by a sealing screw. The upper interior of the sealing cover (14) is penetrated. A valve stem (5) is provided. The sealing ring installed inside the sealing cover (14) is in sealed contact with the outer side of the valve stem (5). Two vertical rods (141) are symmetrically installed on the inner side wall of the sealing cover (14). The vertical rods (141) are inserted into the mounting hole opened in the middle of the upper part of the valve core (9). A sealing disc (15) is installed at the bottom end of the valve stem (5). The sealing gasket installed on the bottom surface of the sealing disc (15) is in sealed contact with the inner side wall of the mounting hole opened in the middle of the upper part of the valve core (9). A pressure sensor (151) is symmetrically installed on the upper surface of the sealing disc (15). When the bottom end of the vertical rod (141) descends to contact the pressure sensor (151) on the sealing disc (15), the vertical rod (141) applies pressure to the pressure sensor (151).

2. The multi-stage pressure reducing regulating valve according to claim 1, characterized in that: The valve body (1) has an inlet (101) and an outlet (102) on its left and right sides respectively. The valve body (1) and the valve cover (2) are connected by studs (4) as well as the valve cover (2) and the packing gland (3). There are two sets of studs (4), and nuts are installed on the outside of the studs (4).

3. The multi-stage pressure reducing regulating valve according to claim 1, characterized in that: The top of the valve stem (5) is connected to an external actuator, and a packing assembly (6) is installed in the space between the valve stem (5) and the valve cover (2).

4. The multi-stage pressure reducing regulating valve according to claim 1, characterized in that: The bottom surface of the valve seat (8) is sealed and fixedly connected to the middle inner wall of the valve body (1) through a gasket. The bottom surface of the valve cover (2) is connected to the top of the valve cage (7) through a gasket. The bottom surface of the valve cage (7) is connected to the upper surface of the valve seat (8) through a gasket. There are three sets of gaskets. The gaskets are made of flexible graphite. The outer side of the bottom surface of the valve core (9) is connected to the inner side wall of the valve seat (8) by a conical hard seal.

5. A multi-stage pressure reducing regulating valve according to claim 1, characterized in that: The valve core (9) has a Y-shaped balance hole (93) inside. A support ring (11) is installed on the upper outer side of the valve core (9). An anti-compression ring (12) is installed below the support ring (11). A spring-loaded sealing ring (13) is installed below the anti-compression ring (12). The outer side of the spring-loaded sealing ring (13) is in sealed contact with the inner wall of the valve cage (7).

6. A multi-stage pressure reducing regulating valve according to claim 1, characterized in that: The pressure-reducing groove (72) is arranged in a circular shape. Both the upper and lower surfaces of the pressure-reducing groove (72) are inclined. The depth of the pressure-reducing groove (72) is less than the wall thickness of the valve cage (7). The depth of the flow hole (71) is equal to the wall thickness of the valve cage (7). The pressure-reducing groove (72) is arranged below the flow hole (71). There is a gap between the pressure-reducing groove (72) and the interior of the valve body (1).

7. A multi-stage pressure reducing regulating valve according to claim 1, characterized in that: The valve core (9) has a circular annular groove (92) on its upper outer side. The groove (92) is located above the throttling groove (91). The two adjacent throttling grooves (91) are staggered. The cross section of the throttling groove (91) is U-shaped. The upper surface of the throttling groove (91) is an inclined surface with rounded corners.

8. A multi-stage pressure reducing regulating valve according to claim 1, characterized in that: The outer side of the perforated plate (10) is arc-shaped, and there is a gap between the outer side of the perforated plate (10) and the inner wall of the valve cage (7).

9. A multi-stage pressure reducing regulating valve according to claim 1, characterized in that: The upper inner diameter of the sealing cover (14) is smaller than the lower inner diameter of the sealing cover (14), and the lower inner diameter of the sealing cover (14) is larger than the diameter of the mounting hole opened in the upper center of the valve core (9).

10. A multi-stage pressure reducing regulating valve according to claim 9, characterized in that: There is a gap between the lower end of the vertical rod (141) and the pressure sensor (151).

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