A pressure reducing control valve

Abstract

The present invention discloses a pressure reducing regulating valve, comprising: a valve body, a main valve seat, a valve core assembly and a stuffing box; the valve body is a three-way structure with a hollow interior; the main valve seat is installed at the bottom of the valve body, and the stuffing box is installed at the top of the valve body; the valve core assembly is installed through the internal cavity of the stuffing box and the internal cavity of the main valve seat; wherein, the internal cavity of the main valve seat serves as the main valve passage. The present invention can be applied to the pressure / flow regulation of high-pressure differential liquid media, and is particularly suitable for occasions requiring a large adjustable ratio at the same time.

Description

Technical Field

[0001] The present invention belongs to the technical field of valves, and in particular relates to a pressure reducing regulating valve. Background Art

[0002] Under large pressure differentials, when a regulating valve uses a single-seat throttling mechanism, as the medium flows through the throat, the flow area decreases dramatically and the medium flow rate increases rapidly. According to the law of conservation of energy, the static pressure decreases due to the conversion into kinetic energy. When the static pressure drops below the saturated vapor pressure at the current temperature of the medium, the liquid medium is converted into bubbles. This process is called flash evaporation. After the medium flows through the throat, the flow rate gradually decreases due to the increase in the flow area, and the static pressure recovers. When the static pressure returns to above the saturated vapor pressure, the bubbles burst. This process is called cavitation. Flash evaporation and cavitation can cause serious damage to valve internals. At the same time, due to the flash evaporation of the medium, a gas-liquid two-phase flow is formed. The expansion and interaction of the two-phase flow causes noise. After the medium pressure in the pipeline behind the valve recovers, the bursting of the bubbles exacerbates the noise and causes severe vibration.

[0003] Furthermore, with the development of industry, there are more and more occasions requiring large adjustable ratios under large pressure differentials. However, due to factors such as machining accuracy, valve sealing capability, and control system sensitivity at low flow rates, achieving large adjustable ratios with a single valve is difficult.

[0004] To solve the above problems, some people use a combination of multi-stage sleeves / labyrinths and pilot structures, trying to use the multi-stage sleeves / labyrinths to solve flash evaporation and cavitation, and use the pilot structure to provide a large adjustable ratio. However, this method has the following disadvantages:

[0005] 1) The processing of sleeves and mazes is relatively complicated;

[0006] 2) The flow channel size is small and the medium is easy to block the flow channel;

[0007] 3) The pilot structure itself does not have a multi-stage pressure reducing function and is easily damaged when the opening is small.

[0008] There is also a double control method, that is, two pressure reducing valves are connected in parallel, one valve is used when the flow is small, and the other valve is used when the flow is large, which invisibly increases the cost of use.

[0009] Therefore, there is an urgent need to develop more suitable valve types to cope with situations that require large pressure difference regulation and large adjustable ratio. Summary of the Invention

[0010] The technical problem solved by the present invention is to overcome the deficiencies of the prior art and provide a pressure reducing regulating valve which can be used for pressure / flow regulation of high pressure differential liquid media, and is particularly suitable for occasions requiring a large adjustable ratio.

[0011] To solve the above technical problems, the present invention discloses a pressure reducing regulating valve, comprising: a valve body, a main valve seat, a valve core assembly and a stuffing box;

[0012] The valve body is a three-way structure with a hollow interior;

[0013] The main valve seat is installed at the bottom of the valve body, and the stuffing box is installed at the top of the valve body; wherein, the main valve seat and the stuffing box are coaxial;

[0014] The valve core assembly is installed through the internal cavity of the stuffing box and the internal cavity of the main valve seat; wherein, the internal cavity of the main valve seat serves as the main valve passage.

[0015] In the above pressure reducing regulating valve, it further comprises: a middle flange, a packing assembly, a packing gland, middle flange bolts and nuts, packing gland bolts and nuts, valve seat set screws, stuffing box spiral wound gaskets and seat pressing spiral wound gaskets;

[0016] The stuffing box is sleeved on the top of the valve body and is pressed by the middle flange, and the middle flange is fastened to the valve body by middle flange bolts and nuts; a stuffing box spiral wound gasket is arranged between the contact surface of the stuffing box and the valve body;

[0017] The main valve seat is sleeved on the bottom of the valve body and is connected and fixed to the valve body by valve seat set screws; a seat pressing spiral wound gasket is arranged between the contact surface of the main valve seat and the valve body.

[0018] The packing assembly is arranged between the valve core assembly and the internal cavity of the stuffing box, the top of the packing assembly is connected to the packing gland, and the packing gland is connected to the top of the stuffing box by packing gland bolts and nuts.

[0019] In the above pressure reducing regulating valve, the inner cavity structure of the main valve seat includes: not less than three evenly distributed guiding ribs, not less than two throttling cavities with different flow areas, arranged in series, and having a connecting shape of a cylinder and a frustum of a cone, a valve seat throttling surface and a valve seat sealing surface.

[0020] In the above pressure reducing regulating valve, the valve core assembly includes: a main valve core, a pilot valve core, a spring gland and an elastic component;

[0021] The elastic component, the spring gland and the main valve core are installed in sequence from top to bottom;

[0022] The main valve core is installed in the internal cavity of the main valve seat to form a main valve flow path for regulating the flow area of the main valve passage;

[0023] The pilot valve core is installed in the main valve core to form a pilot valve flow path;

[0024] The spring gland is fixed to the main valve core by bolts.

[0025] In the above pressure reducing regulating valve, the main valve core includes: a pilot valve seat sealing surface, a throttle core, a main valve core sealing surface, a main valve core head, a valve core throttle surface, and an internal flow passage of the main valve core;

[0026] The pilot valve seat sealing surface and the main valve core sealing surface are respectively located at two end faces of the main valve core;

[0027] The number of throttle cores is not less than two, and they are axially distributed on the outside of the main valve core;

[0028] The main valve core head is located at the top of the main valve core; among them, the main valve core head is always located within the uniformly distributed guiding ribs to ensure the stability of the valve stem under the working condition of medium scouring;

[0029] The valve core throttle surface is located on the side of the main valve core;

[0030] The hollow inner cavity of the main valve core forms the internal flow passage of the main valve core, and the pilot valve core is installed in the internal flow passage of the main valve core and can move up and down in the internal flow passage of the main valve core.

[0031] In the above pressure reducing regulating valve,

[0032] When the main valve flow path is closed, the valve core throttle surface corresponds and fits with the valve seat throttle surface of the same level, and the main valve core sealing surface and the valve seat sealing surface form a sealing pair to cut off the main valve flow path;

[0033] When the pilot valve flow path and the main valve flow path are both closed, the pilot valve seat sealing surface and the pilot valve core sealing surface of the pilot valve core are sealed and fitted, and the valve is sealed.

[0034] In the above pressure reducing regulating valve, the pilot valve core includes: a pilot valve core end flow passage window, a pilot valve core sealing surface, a pilot valve balance hole, a valve stem, a pilot valve core limit block, and an opening and closing guiding ring;

[0035] One end of the valve stem is connected to an external actuator, and the other end is connected to the opening and closing guiding ring; among them, the valve stem drives the valve core assembly to move axially up and down by the force provided by the external actuator to realize the opening, closing, and adjustment of the valve;

[0036] The opening and closing guiding ring and the pilot valve core limit block are connected by an elastic component;

[0037] The pilot valve balance hole is arranged on the pilot valve core limit block;

[0038] The pilot valve core sealing surface is arranged between the pilot valve core end flow passage window and the pilot valve core limit block and is used to seal the internal flow passage of the main valve core.

[0039] In the above pressure reducing regulating valve,

[0040] Under the control of the valve stem, the pilot valve core adjusts the opening or closing of the pilot valve core end flow passage window;

[0041] When the pilot valve core moves away from the internal flow passage of the main valve core, the main valve core is driven to move in the same direction through the spring gland and the pilot valve core limiting block to open the main valve passage.

[0042] In the above pressure reducing regulating valve, a bottom flow passage window of the stuffing box is provided; wherein, the bottom flow passage window of the stuffing box is axially symmetric in shape and proportionally increased or decreased in size with the end flow passage window of the pilot valve core; during the movement of the pilot valve core, the medium flow area of the bottom flow passage window 51 of the stuffing box and the end flow passage window of the pilot valve core is proportionally increased or decreased;

[0043] The bottom flow passage window of the stuffing box is the medium flow inlet of the pilot valve flow path, and is opened or closed under the control of the opening and closing guide ring on the valve stem.

[0044] In the above pressure reducing regulating valve, the elastic component is a compression spring or a disc spring.

[0045] The present invention has the following advantages:

[0046] (1) The present invention discloses a pressure reducing regulating valve, which can not only ensure that the medium does not cavitate under high pressure difference, but also realize a valve with a large adjustable ratio. The valve type has a simple structure and is easy to process; both the main valve and the pilot valve have a multi-stage pressure reducing function; and the flow diameter is large, and the medium will not block the flow passage.

[0047] (2) The present invention discloses a pressure reducing regulating valve, which has two flow paths of a pilot valve and a main valve. Compared with the flow area of the main valve, the flow passage area of the pilot valve is one order of magnitude smaller, which can greatly reduce the minimum flow rate through the pilot valve, thereby improving the adjustable ratio of the valve. Description of the Drawings

[0048] Figure 1 is the structural schematic diagram of a pressure reducing regulating valve in an embodiment of the present invention;

[0049] Figure 2 [[ID=2B]]is the structural schematic diagram of a main valve seat in an embodiment of the present invention;

[0050] Figure 3 is the schematic diagram of the natural state and the compressed state (the pilot valve is closed) of a valve core assembly in an embodiment of the present invention;

[0051] Figure 4 is the structural schematic diagram of an integral valve stem and a pilot valve core in an embodiment of the present invention;

[0052] Figure 5 is the partial schematic diagram of the flow passage of the stuffing box in an embodiment of the present invention;

[0053] Figure 6 is the partial enlarged schematic diagram of the bottom flow passage window of the stuffing box and the end flow passage window of the pilot valve core in an embodiment of the present invention;

[0054] Figure 7 It is a schematic diagram of the flow of the medium when the valve of the pressure reducing regulating valve is at a small opening in the embodiment of the present invention;

[0055] Figure 8 It is a schematic diagram of the flow of the medium when the valve of the pressure reducing regulating valve is at a large opening in the embodiment of the present invention. Specific Embodiments

[0056] To make the objectives, technical solutions and advantages of the present invention clearer, the following will further describe in detail the disclosed embodiments of the present invention with reference to the accompanying drawings.

[0057] The present invention provides a pressure reducing regulating valve, which includes a valve body, a main valve seat and a stuffing box. Among them, a valve stem controlled by an external power is installed in the stuffing box; and there is a stuffing box bottom flow channel window on the stuffing box as the medium flow inlet of the pilot valve flow path; the stuffing box bottom flow channel window is controlled by an opening and closing guide ring on the valve stem to open or close. The spool assembly: includes a main spool with a main spool internal flow path and a pilot spool, which are used to form the main valve flow path and the pilot valve flow path; the main spool is installed in the internal cavity of the main valve seat to form the main valve flow path for adjusting the flow area of the main valve channel; the pilot spool is installed inside the main spool, and the pilot spool is controlled by the valve stem to adjust the opening or closing of the flow channel window at the end of the pilot spool; and when the pilot spool moves away from the main spool internal flow path, it will drive the main spool to move in the same direction through the limiting structure of the main spool and the pilot spool to open the main valve channel.

[0058] As Figure 1 , in this embodiment, the pressure reducing regulating valve includes: a valve body 1, a main valve seat 2, a spool assembly 3 and a stuffing box 5.

[0059] The valve body 1 serves as the shell structure of the pressure reducing regulating valve and is a three-way structure with a hollow interior. The main valve seat 2 is installed at the bottom of the valve body 1, the stuffing box 5 is installed at the top of the valve body 1, and the main valve seat 2 and the stuffing box 5 are coaxial. The spool assembly 3 is installed through the internal cavities of the stuffing box 5 and the main valve seat 2; among them, the internal cavity of the main valve seat 2 serves as the main valve channel.

[0060] In this embodiment, the pressure reducing regulating valve may further include fastening and sealing components; among them, the fastening and sealing components are used to fasten and seal the valve body 1, the main valve seat 2 and the stuffing box 5, and specifically may include: a middle flange 6, a packing assembly 10, a packing pressing plate 11, middle flange bolts and nuts 12, packing pressing plate bolts and nuts 13, valve seat set screws 14, a stuffing box spiral wound gasket 15 and a pressing valve seat spiral wound gasket 16.

[0061] Preferably, the stuffing box 5 is sleeved on the top of the valve body 1 and is pressed tightly by the middle flange 6. The middle flange 6 is fastened to the valve body 1 through the middle flange bolts and nuts 12. And a stuffing box spiral gasket 15 is arranged between the contact surfaces of the stuffing box 5 and the valve body 1, ensuring that the medium will not leak from the gap between the valve body 1 and the stuffing box 5.

[0062] Preferably, the main valve seat 2 is sleeved on the bottom of the valve body 1 and is connected and fixed to the valve body 1 through the valve seat set screws 14. And a pressing valve seat spiral gasket 16 is arranged between the contact surfaces of the main valve seat 2 and the valve body 1, ensuring that the medium will not leak from the gap between the valve body 1 and the valve seat 2.

[0063] Preferably, the packing assembly 10 is arranged between the internal cavities of the valve core assembly 3 and the stuffing box 5. The top of the packing assembly 10 is connected to the packing pressing plate 11, and the packing pressing plate 11 is connected to the top of the stuffing box 5 through the packing pressing plate bolts and nuts 13. During the process of tightening the packing pressing plate bolts and nuts 13, the packing pressing plate 11 transmits the force to the packing assembly 10, compressing the packing assembly 10 so that the packing assembly 10 is closely attached to the valve stem 324 and the inner wall of the stuffing box 5 respectively, ensuring that the medium will not leak from the gaps among the three.

[0064] In the embodiment of the present invention, as Figure 2 , the inner cavity structure of the main valve seat 2 may specifically include: no less than three evenly distributed guiding ribs 21, no less than two throttling cavities 22 with different flow areas, arranged in series, and having a connecting shape of a cylinder and a frustum of a cone, a valve seat throttling surface 23 and a valve seat sealing surface 24.

[0065] In the embodiment of the present invention, as Figure 3 and Figure 4 , the valve core assembly 3 may specifically include: a main valve core 31, a pilot valve core 32, a spring gland 33 and an elastic member 34. Among them, the elastic member 34, the spring gland 33 and the main valve core 31 are installed in sequence from top to bottom; the main valve core 31 is installed in the internal cavity of the main valve seat 2 to form a main valve flow path for adjusting the flow area of the main valve channel; the pilot valve core 32 is installed in the main valve core 31 to form a pilot valve flow path; the spring gland 33 is fixed to the main valve core 31 through bolts; the elastic member 34 is installed between the opening and closing guiding ring 326 and the spring gland 33, and the elastic member 34 is used to maintain the relative position of the pilot valve core 32 and the main valve core 31 stable during the movement process, and make the main valve core 31 tend to move towards the main valve seat 2 when the main valve is not opened.

[0066] In the embodiment of the present invention, the main valve core 31 may specifically include: a pilot valve seat sealing surface 311, a throttling core 312, a main valve core sealing surface 313, a main valve core head 314, a valve core throttling surface 315 and a main valve core internal flow path 316.

[0067] The pilot valve seat sealing surface 311 and the main spool sealing surface 313 are respectively located at two end faces of the main spool 31; the number of throttle cores 312 is not less than two and is axially distributed on the outside of the main spool 31; the main spool head 314 is located at the top of the main spool 31, and the main spool head 314 is always located within the evenly distributed guiding ribs 21 to ensure the stability of the valve stem 324 under the condition of medium erosion; the spool throttle surface 315 is located on the side of the main spool 31; the hollow inner cavity of the main spool 31 forms the main spool internal flow channel 316, and the pilot spool 32 is installed in the main spool internal flow channel 316 and can move up and down within the main spool internal flow channel 316.

[0068] Preferably, when the main valve flow path is closed, the spool throttle surface 315 fits corresponding to the valve seat throttle surface 23 of the same level, and the main spool sealing surface 313 and the valve seat sealing surface 24 form a sealing pair to cut off the main valve flow path; when the pilot valve flow path and the main valve flow path are both closed, the pilot valve seat sealing surface 311 and the pilot spool sealing surface 322 of the pilot spool 32 are hermetically fitted, and the valve is sealed.

[0069] In the embodiment of the present invention, the pilot spool 32 may specifically include: a pilot spool end flow channel window 321, a pilot spool sealing surface 322, a pilot valve balance hole 323, a valve stem 324, a pilot spool limit block 325, and an opening and closing guiding ring 326.

[0070] One end of the valve stem 324 is connected to an external actuator, and the other end is connected to the opening and closing guiding ring 326; wherein, the valve stem 324 drives the spool assembly 3 to move axially up and down by the force provided by the external actuator to realize the opening, closing, and adjustment of the valve. The pilot valve balance hole 323 is arranged on the pilot spool limit block 325; the pilot spool sealing surface 322 is arranged between the pilot spool end flow channel window 321 and the pilot spool limit block 325 for closing the main spool internal flow channel 316. The opening and closing guiding ring 326 and the pilot spool limit block 325 are connected by an elastic member 34.

[0071] As described above, the pilot spool 32 can slide up and down within the main spool internal flow channel 316, up to contact with the spring gland 33, and down to make the pilot spool sealing surface 322 fit with the pilot valve seat sealing surface 311; correspondingly, the elastic member 34 is gradually compressed during the upward movement of the pilot spool 32, and the compression amount becomes smaller during the downward movement, and the spring gland 33 guides the movement of the elastic member 34. Among them, the elastic member 34 can adopt a cylindrical compression spring or a disc spring.

[0072] Preferably, under the control of the valve stem 324, the pilot spool 32 adjusts the opening or closing of the pilot spool end flow channel window 321; when the pilot spool 32 moves in a direction away from the main spool internal flow channel 316, it drives the main spool 31 to move in the same direction through the spring gland 33 and the pilot spool limit block 325 to open the main valve passage.

[0073] In this embodiment, as Figure 5 shown, a stuffing box bottom flow channel window 51 is provided on the stuffing box 5. The stuffing box bottom flow channel window 51 is the medium flow inlet of the pilot valve flow path, and is controlled by the opening and closing guide ring 326 on the valve stem 324 to be opened or closed. Among them, the stuffing box bottom flow channel window 51 and the pilot valve core end flow channel window 321 are axially symmetric in shape and increase or decrease in proportion in size; during the movement of the pilot valve core 32, the medium flow area of the stuffing box bottom flow channel window 51 and the pilot valve core end flow channel window 321 increases or decreases in proportion. For example, during the upward movement of the valve stem 324, the stuffing box bottom flow channel window 51 is exposed from bottom to top, while the pilot valve core end flow channel window 321 is exposed from top to bottom, and the exposed area always maintains a certain ratio, as Figure 6 shown. When the pilot valve is closed, the opening and closing guide ring 326 blocks the stuffing box bottom flow channel window 51 driven by the valve stem 324, and the pilot valve core sealing surface 322 and the pilot valve seat sealing surface 311 are fitted to form a seal; when the pilot valve is opened, the stuffing box bottom flow channel window 51 is gradually exposed, and is connected to the simultaneously exposed pilot valve core end flow channel window 321. The pilot valve core sealing surface 322 and the pilot valve seat sealing surface 311 are separated, and the medium flows in from the stuffing box bottom flow channel 51 window, passes through the valve stem balance hole 323, the pilot valve core end flow channel window 321, and the main valve core internal flow channel and then flows out from 316. By changing the shapes of the stuffing box bottom flow channel window 51 and the pilot valve core end flow channel window 321, the flow characteristics of the valve can be changed. The common flow characteristics include linear, equal percentage, quick opening, etc.

[0074] In the embodiment of the present invention, in combination with Figures 1 to 8 it can be seen that the main valve flow path is formed by the cooperation of the main valve seat 2 and the main valve core 31. The inner cavity of the main valve seat 2 has at least two throttling cavities 22 with different flow areas and a group of at least three uniformly distributed guide ribs 21. The throttling cavities 22 are cylindrical and frustum-shaped, and at least two throttling cavities 22 with different flow areas are arranged in series axially. Corresponding to the main valve seat 2, there are at least two frustum-shaped throttling cores 312 on the outside of the main valve core 31. The at least two frustum-shaped throttling cores 312 can axially move inside the throttling cavity 22, and at the same time change the flow area of each stage of the main flow path, so as to realize the regulation and decompression of the main flow path. When the main valve flow path is closed, the valve core throttling surface 315 is correspondingly fitted with the same-level valve seat throttling surface 23, and the end sealing surface 313 of the main valve core 31 can form a sealing pair with the sealing surface 24 of the main valve seat 2 to cut off the main valve flow path, as Figure 7 shown.

[0075] When the valve is closed, the pilot valve flow path and the main valve flow path are closed at the same time. The pilot valve core sealing surface 322 is in contact with the pilot valve seat sealing surface 311, and the main valve core sealing surface 313 is in contact with the valve seat sealing surface 24, and the valve is sealed. When the valve is adjusted to a small flow rate (from the time when the pilot valve core sealing surface 322 and the pilot valve seat sealing surface 311 are separated to the time when the upper surface of the limit block 325 does not touch the lower surface of the spring pressure cover 33), as shown in FIG. Figure 7 As shown, due to the force of the elastic component 34, the main valve core sealing surface 313 and the valve seat sealing surface 24 are still in contact, the main valve flow path is still closed, and the valve stem 324 drives the pilot valve core 32 to slide in the main valve core 31, only changing the flow area of the pilot valve flow path to adjust the flow rate. The flow channel window 51 at the bottom of the stuffing box and the flow channel window 321 at the end of the pilot valve core form multi-stage pressure reduction due to the proportional change of the flow area; when the valve flow rate is further increased to the maximum opening (after the upper surface of the limit block 325 touches the lower surface of the spring cover 33), as shown in FIG. Figure 8 As shown, the pilot valve flow path has been fully opened, the valve stem 324 continues to move upward, the limit block 325 drives the spring pressure cover 33 and the main valve core 31 fixed together to move upward, the main valve core sealing surface 313 is separated from the main valve seat sealing surface 24, and the main valve flow path is opened. At this time, the medium will pass through the multi-stage channel 4 formed by the main valve core and the main valve seat; similarly, with the axial movement of the valve stem, the flow area of the multi-stage channel 4 increases or decreases proportionally, reducing the possibility of cavitation. During the upward movement of the valve core assembly 3, the main valve core head position 314 is always inside the uniformly distributed guide rib 21, which can ensure the stability of the valve stem under medium flushing conditions. Conversely, when the flow rate decreases, the main valve opening will first decrease with the flow rate until it is closed (the pilot valve is still open at this time). As the flow rate further decreases, the pilot valve opening gradually decreases until it is closed.

[0076] When the valve core assembly 3 moves to a certain opening, different parts of the throttling chamber 22 and the throttling surface 315 of the valve core at the same level form throttling rings with different flow areas, which determine the valve's flow capacity at that opening. By changing the opening, the valve's flow resistance coefficient is adjusted, thereby regulating the valve's pressure / flow. The medium enters the multi-stage flow channel 4 formed by the valve core assembly 3 and the main valve seat 2. The flow capacity of the multi-stage flow channel 4 is a dynamic variable. When the valve core assembly 3 moves upward, the flow capacity increases; when the valve core assembly 3 moves downward, the flow capacity decreases. At any opening of the valve core assembly 3, the expansion channel 41 within the multi-stage flow channel 4 decelerates the medium, while the contraction channel 42 redirects and accelerates the medium. The pressure differential is distributed across multiple stages during this continuous process of deceleration, direction change, and acceleration. Compared with single-seat throttling, the pressure difference borne by each stage is smaller, and the static pressure can be maintained more stably above the saturated steam pressure, thereby effectively preventing the generation of cavitation and cavitation, thereby eliminating the noise and vibration of the pipeline after the valve; at the same time, the flow rate of the medium is low, and the erosion of the valve trim is not great, thereby extending the service life of the valve trim.

[0077] When the main spool 31 operates, since the pilot spool 32 has been opened, the pressure on the upper surface of the main spool can be partially discharged from the pilot valve flow passage 43, reducing the pressure difference between the upper and lower surfaces of the main valve, decreasing the unbalanced force of the valve opening and closing, and the actuator can be reduced; when the valve is closed, since the pilot valve has been closed, the medium force acts entirely on the upper surface of the main valve, increasing the sealing specific pressure of the valve and improving the valve sealing level.

[0078] Among them, it should be noted that in this embodiment, the number of stages of the main spool flow passage can be set according to the actual working conditions to ensure that the medium does not flash; at the same time, a large flow area is reserved to ensure that the valve operation is not stuck.

[0079] Although the present invention has been disclosed above with preferred embodiments, it is not used to limit the present invention. Any person skilled in the art can make possible changes and modifications to the technical solution of the present invention by using the methods and technical contents disclosed above without departing from the spirit and scope of the present invention. Therefore, any simple modification, equivalent change and modification made to the above embodiments based on the technical essence of the present invention without departing from the technical solution of the present invention shall fall within the protection scope of the technical solution of the present invention.

[0080] The content not detailedly described in the specification of the present invention belongs to the well-known technology of those skilled in the art.

Claims

1. A pressure reducing control valve, characterized in that, Comprising: Valve body (1), main valve seat (2), spool assembly (3) and stuffing box (5); The valve body (1) is a three-way structure with a hollow interior; The main valve seat (2) is installed at the bottom of the valve body (1), and the stuffing box (5) is installed at the top of the valve body (1); wherein, the main valve seat (2) is coaxial with the stuffing box (5); The spool assembly (3) is installed through the internal cavity of the stuffing box (5) and the internal cavity of the main valve seat (2); wherein, the internal cavity of the main valve seat (2) serves as the main valve passage; The spool assembly (3) includes: main spool (31), pilot spool (32), spring gland (33) and elastic component (34); wherein, the elastic component (34), spring gland (33) and main spool (31) are installed in sequence from top to bottom; the main spool (31) is installed in the internal cavity of the main valve seat (2) to form the main valve flow path for adjusting the flow area of the main valve passage; the pilot spool (32) is installed inside the main spool (31) to form the pilot valve flow path; the spring gland (33) is fixed to the main spool (31) by bolts; the elastic component (34) is a compression spring or a disc spring; The stuffing box (5) is provided with a stuffing box bottom flow channel window (51); wherein, the stuffing box bottom flow channel window (51) is axially symmetric in shape and proportionally increased or decreased in size with the pilot spool end flow channel window (321) of the pilot spool (32); during the movement of the pilot spool (32), the medium flow area of the stuffing box bottom flow channel window 51 and the pilot spool end flow channel window (321) is increased or decreased proportionally; the stuffing box bottom flow channel window (51) is the medium flow inlet of the pilot valve flow path and is controlled by the opening and closing guide ring (326) on the valve stem (324) of the pilot spool (32) to achieve opening or closing.

2. The pressure reducing regulating valve according to claim 1, wherein, Also comprising: Intermediate flange (6), packing assembly (10), packing gland (11), intermediate flange bolts and nuts (12), packing gland bolts and nuts (13), valve seat set screws (14), stuffing box spiral wound gasket (15) and pressing valve seat spiral wound gasket (16); The stuffing box (5) is sleeved on the top of the valve body (1) and is pressed by the intermediate flange (6), and the intermediate flange (6) is fastened to the valve body (1) by the intermediate flange bolts and nuts (12); a stuffing box spiral wound gasket (15) is provided between the contact surfaces of the stuffing box (5) and the valve body (1); The main valve seat (2) is sleeved on the bottom of the valve body (1) and is connected and fixed to the valve body (1) by the valve seat set screws (14); a pressing valve seat spiral wound gasket (16) is provided between the contact surfaces of the main valve seat (2) and the valve body (1); The packing assembly (10) is arranged between the spool assembly (3) and the internal cavity of the stuffing box (5), the top of the packing assembly (10) is connected to the packing gland (11), and the packing gland (11) is connected to the top of the stuffing box (5) by the packing gland bolts and nuts (13).

3. The pressure reducing control valve according to claim 1, characterized in that The inner cavity structure of the main valve seat (2) includes: no less than three uniformly distributed guide ribs (21), no less than two throttling cavities (22) with different flow areas, arranged in series, and with the connection shape of a cylinder and a frustum of a cone, a valve seat throttling surface (23) and a valve seat sealing surface (24).

4. The pressure reducing regulating valve according to claim 3, wherein The main spool (31) includes: a pilot valve seat sealing surface (311), a throttle core (312), a main spool sealing surface (313), a main spool head (314), a spool throttle surface (315), and a main spool internal flow passage (316); The pilot valve seat sealing surface (311) and the main spool sealing surface (313) are respectively located at two end faces of the main spool (31); The number of throttle cores (312) is not less than two, and they are axially distributed on the outer side of the main spool (31); The main spool head (314) is located at the top of the main spool (31); wherein, the main spool head (314) is always located within the uniformly distributed guiding ribs (21) to ensure the stability of the valve stem (324) under the condition of medium scouring; The spool throttle surface (315) is located on the side of the main spool (31); The hollow inner cavity of the main spool (31) forms the main spool internal flow passage (316), and the pilot spool (32) is installed in the main spool internal flow passage (316) and can move up and down within the main spool internal flow passage (316).

5. The pressure reducing regulating valve according to claim 4, wherein When the main valve flow path is closed, the spool throttle surface (315) corresponds to and fits with the valve seat throttle surface (23) of the same level, and the main spool sealing surface (313) and the valve seat sealing surface (24) form a sealing pair to cut off the main valve flow path; When the pilot valve flow path and the main valve flow path are both closed, the pilot valve seat sealing surface (311) and the pilot spool sealing surface (322) of the pilot spool (32) are hermetically fitted, and the valve is sealed.

6. The pressure reducing regulating valve according to claim 4, characterized in that, The pilot spool (32) includes: a pilot spool end flow passage window (321), a pilot spool sealing surface (322), a pilot valve balance hole (323), a valve stem (324), a pilot spool limit block (325), and an opening and closing guiding ring (326); One end of the valve stem (324) is connected to an external actuator, and the other end is connected to the opening and closing guiding ring (326); wherein, the valve stem (324) drives the spool assembly (3) to move axially up and down through the force provided by the external actuator to realize the opening, closing, and adjustment of the valve; The opening and closing guiding ring (326) and the pilot spool limit block (325) are connected by an elastic member (34); The pilot valve balance hole (323) is provided on the pilot spool limit block (325); The pilot spool sealing surface (322) is arranged between the pilot spool end flow passage window (321) and the pilot spool limit block (325) for closing the main spool internal flow passage (316).

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