Multistage pressure reducing cage-type throttle valve

Abstract

This invention discloses a multi-stage pressure-reducing cage-type throttle valve, relating to the field of fluid control valve technology. The throttle valve includes a valve body, a valve stem, and a multi-stage cage assembly coaxially nested from the outside in, with the valve stem extending into the innermost cage. The throttling grooves of the innermost cage are arranged in multiple segments along the axial direction, with adjacent segments axially separated by a solid sidewall of the cage. The lower edge of the upper segment is axially connected to the upper edge of the lower segment, ensuring a constant increase in the effective flow area per unit stroke of the valve stem and achieving linear opening adjustment. The throttling grooves of the first and second stage cages are staggered, and the valve body adopts a split structure with upper and lower positioning seats. This invention significantly improves the structural strength of the cage while eliminating flow plateaus and step fluctuations, achieving high adjustment accuracy, good system stability, and simple processing and maintenance. It is suitable for high-pressure fluid transportation applications in petroleum, chemical, and natural gas industries.

Description

Technical Field

[0001] This invention relates to the field of fluid control valve technology, and in particular to a multi-stage pressure reducing cage-type throttle valve for use in high-pressure fluid transportation systems such as those for petroleum, chemical, and natural gas. Background Technology

[0002] Multi-stage pressure-reducing cage-type throttle valves are core equipment in high-pressure fluid transportation systems for regulating the pressure and flow rate of the medium. Through the progressive throttling effect of multiple cages, they reduce the pressure of the high-pressure medium to the target range while simultaneously achieving precise flow control. However, with the increasing demands for fluid control precision in industrial production, the linear regulation performance deficiencies of existing three-stage pressure-reducing cage-type throttle valves are becoming increasingly prominent.

[0003] In the prior art, Chinese invention patent No. ZL2021108195614 discloses a three-stage pressure-reducing cage-type throttle valve, which includes a valve body, a valve cover, a valve stem, and a handwheel. Between the inlet and outlet flow channels of the valve body, a first-stage cage, a second-stage cage, and a third-stage cage are coaxially nested from the outside in. Each stage of the cage has a first-stage throttling orifice, a second-stage throttling orifice, and a third-stage throttling orifice respectively on its sidewall. The third-stage throttling orifices are arranged in an arithmetic sequence around the axis of the third-stage cage, with the number of orifices in the six rows being 6, 5, 4, 3, 2, and 1 respectively. The first-stage and second-stage throttling orifices at the same height are staggered, achieving high pressure drop regulation through the three-stage throttling structure.

[0004] While this technical solution expands the pressure drop range and improves the uniformity of medium flow velocity to some extent, it still has the following significant drawbacks: 1. Insufficient linear regulation performance: The three-stage throttling orifice uses an arithmetic sequence of circular holes, and the flow area increases in a stepwise manner with the valve stem opening. When the valve stem moves to the solid area between two adjacent rows of circular holes, the flow area stops increasing, forming a significant flow plateau. When the valve stem moves to the next row of circular holes, the flow area jumps again, making it impossible to achieve strict proportional linear regulation. This results in insufficient valve regulation accuracy, large flow fluctuations, and a tendency to cause water hammer, vibration, and noise problems in the pipeline.

[0005] 2. The fundamental contradiction between linearity and strength remains unresolved: To improve the strength of the cage structure, this design uses a circular hole structure instead of a continuous slot structure. However, the circular hole structure has limited effect on improving linearity. If a continuous slot structure is used to further improve linearity, the sidewall of the cage will be cut into multiple independent vertical thin plates. Under high pressure differential conditions, these thin plates are extremely susceptible to radial force, causing outward bulging deformation or even breakage, significantly shortening the valve's service life.

[0006] 3. High processing difficulty and poor batch consistency: The linear adjustment of this solution relies on the differentiated arrangement of different rows of orifices, requiring the processing of multiple rows of throttling orifices with different numbers of orifices on the same cage sleeve. The processing technology is complex and requires high dimensional accuracy. Positional and orifice diameter errors generated during processing will further amplify the linearity deviation, resulting in poor performance consistency of products produced in batches.

[0007] In summary, the existing three-stage pressure-reducing cage-type throttle valve has not fundamentally solved the technical contradiction of "the incompatibility between linear regulation performance and structural strength", and cannot simultaneously meet the strength requirements and high-precision regulation needs under high-pressure conditions. Summary of the Invention

[0008] The purpose of this invention is to overcome the shortcomings of the prior art and provide a multi-stage pressure reducing cage-type throttle valve to solve the technical problems of insufficient linear regulation performance, prominent contradiction between linearity and strength, and high processing difficulty in the prior art, so as to achieve high-precision linear regulation under high pressure conditions, while ensuring that the valve has sufficient structural strength and good manufacturability.

[0009] To achieve the above objectives, the present invention provides a multi-stage pressure reducing cage-type throttle valve, comprising a valve body (1) and a valve stem (2). A multi-stage cage assembly (3) is provided between the medium inlet (101) and the medium outlet (102) of the valve body (1) and is coaxially nested from the outside to the inside. The valve stem (2) extends into the innermost cage of the multi-stage cage assembly (3). The key feature is that the throttling groove of the innermost cage is distributed along the axial direction with an equal flow area increment, so that the increment of the effective flow area remains constant for each unit stroke of the valve core (2) moving axially, thereby realizing the linear opening adjustment of the multi-stage cage assembly (3).

[0010] Furthermore, the multi-stage cage assembly (3) includes a first-stage cage (301), a second-stage cage (302), and a third-stage cage (303) coaxially nested from the outside to the inside, with a first-stage throttling groove (3011), a second-stage throttling groove (3021), and a third-stage throttling groove (3031) respectively opened on the first-stage cage (301), the second-stage cage (302), and the third-stage cage (303).

[0011] Furthermore, both the primary throttling groove (3011) and the secondary throttling groove (3021) are arranged in multiple rows in the circumferential direction, and the primary throttling groove (3011) and the secondary throttling groove (3021) at the same height are arranged in a staggered manner.

[0012] Furthermore, the three-stage throttling groove (3031) is arranged in a multi-layer segmented manner along the axial direction of the three-stage cage (303). Each layer of groove is arranged at equal intervals along the circumferential direction, and adjacent layers of groove are separated by the side wall solid of the three-stage cage (303) along the axial direction. The lower edge of the upper layer groove is connected to the upper edge of the lower layer groove in the axial direction. When the valve stem (2) moves upward, the sum of the effective flow areas of each layer of groove increases linearly in proportion to the valve stem opening.

[0013] Furthermore, the valve body (1) adopts a split structure, including a valve cover (104) and a valve seat (105) that can be detachably connected by a flange (103). The valve cover (104) is provided with an upper positioning seat (106) on the top contour of the multi-stage cage assembly (3), and the valve seat (105) is provided with a lower positioning seat (107) on the bottom contour of the multi-stage cage assembly (3). A medium flow channel is arranged around the outermost cage of the multi-stage cage assembly (3) in the valve cover (104), and a medium inlet (101) is provided tangentially in the medium flow channel. A medium outlet (102) communicating with the inner cavity of the innermost cage is provided at the bottom of the valve cover (105).

[0014] Furthermore, the valve cover (103) is also provided with a packing seat (108) for sealing connection.

[0015] Furthermore, the packing seat (108) is connected to the valve stem (2) via a packing gland (109).

[0016] Furthermore, a valve stem nut (110) is provided on the central tube of the packing gland (109), and the valve stem (2) is screwed into the valve stem nut (110) through the thread on the upper section.

[0017] Furthermore, a thrust bearing (110) is installed in the central tube of the pressure cap (109), and a flange (201) adapted to the opening of the central tube is formed on the valve stem (2). A spring (111) is sleeved on the valve stem (2) of the thrust bearing (110) and the flange (201), and the upper and lower ends of the spring (111) are fixedly connected to the flange (201) and the thrust bearing (110) respectively.

[0018] Furthermore, the upper end of the valve stem (2) receives rotational power through a connecting handwheel (202), and the lower end of the valve stem (2) is rounded.

[0019] Compared with the prior art, the significant advantages of the present invention are: 1. Completely resolves the technical contradiction between linear regulation performance and structural strength: This invention utilizes a multi-layered, segmented arrangement of the innermost cage-like throttling groove, along with a structural design where the upper and lower edges of adjacent groove segments are axially connected. This design retains the continuous solid portion of the cage-like sidewall as a reinforcing structure, significantly improving the structural strength of the cage-like structure, while simultaneously achieving a strictly proportional linear increase in the effective flow area with the valve stem opening. This structure avoids the defects of insufficient strength and easy deformation and fracture under high pressure inherent in continuous groove structures, and eliminates the flow plateau and stepped fluctuations of traditional circular orifice structures, truly achieving a balance between linearity and strength.

[0020] 2. Improved regulation accuracy and system stability: Since the increase in effective flow area remains constant, the valve flow rate changes smoothly with the opening degree, avoiding water hammer, vibration and noise in the pipeline caused by flow fluctuations, and greatly enhancing the stability and safety of the fluid transport system.

[0021] 3. Simple structure and low processing and maintenance costs: All grooves in this invention have the same width, eliminating the need for differentiated layouts. The processing technology is simple, dimensional accuracy is easy to guarantee, and the performance consistency of mass-produced products is good. At the same time, the split valve body structure makes the installation, disassembly, and maintenance of the multi-stage cage assembly extremely convenient, reducing the use and maintenance costs of the valve.

[0022] 4. Wide applicability and long service life: The cage structure of this invention has high strength and can withstand high pressure differentials, making it suitable for various harsh working conditions such as high pressure, high temperature, and strong corrosion. At the same time, its excellent linear regulation characteristics reduce uneven erosion of the internal components of the valve by the medium, effectively extending the valve's service life. Attached Figure Description

[0023] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0024] Figure 1 This is a schematic diagram of the overall structure of the multi-stage pressure reducing cage-type throttle valve in this invention (I); Figure 2 This is a schematic diagram (II) of the overall structure of the multi-stage pressure reducing cage-type throttle valve in this invention; Figure 3 This is a schematic diagram (I) of the internal structure of the multi-stage pressure reducing cage-type throttle valve in this invention; Figure 4 This is a schematic diagram (II) of the internal structure of the multi-stage pressure reducing cage-type throttle valve in this invention. Figure 5 This is a top view of the multi-stage pressure reducing cage-type throttle valve in this invention; Figure 6 yes Figure 5 A cross-sectional view along the AA direction; Figure 7 Figure 1 is a schematic diagram of the assembly structure of the multi-stage pressure reducing cage-type throttle valve in this invention (I). Figure 8 Figure 2 shows a schematic diagram of the assembly structure of the multi-stage pressure reducing cage-type throttle valve in this invention. Figure 9 yes Figure 8 Enlarged view of part B in the middle; In the diagram, the following numbers are used: 1-Valve body; 101-Medium inlet; 102-Medium outlet; 103-Flange; 104-Valve cover; 105-Valve seat; 106-Upper positioning bracket; 107-Lower positioning bracket; 108-Packing seat; 109-Packing gland; 110-Valve stem nut; 111-Thrust bearing; 112-Spring; 2-Valve stem; 201-Flange; 202-Handwheel; 3-Multi-stage cage assembly; 301-First-stage cage; 3011-First-stage throttling groove; 302-Second-stage cage; 3021-Second-stage throttling groove; 303-Third-stage cage; 3031-Third-stage throttling groove. Detailed Implementation

[0025] Embodiments of the present invention are described in detail below, examples of which are illustrated in the accompanying drawings, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and intended to explain the present invention, and should not be construed as limiting the present invention.

[0026] In the description of this invention, it should be understood that the terms "length," "width," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," and "outer," etc., indicating orientation or positional relationships, are based on the orientation or positional relationships shown in the accompanying drawings and are only for the convenience of describing the invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of the invention. Furthermore, in the description of this invention, "a plurality of" means two or more, unless otherwise explicitly specified.

[0027] like Figures 1 to 9 As shown, the multi-stage pressure-reducing cage-type throttle valve disclosed in this embodiment mainly includes three parts: valve body 1, valve stem 2, and multi-stage cage assembly 3. Valve body 1 provides a channel for the flow of the medium and also serves as the mounting base for other components; valve stem 2 is used to receive external power and achieve axial movement to adjust the valve opening; multi-stage cage assembly 3 is used to achieve progressive pressure reduction and flow control of the medium.

[0028] The valve body 1 adopts a split structure, including a valve cover 104 and a valve seat 105, which are detachably connected by a flange 103 (a sealing gasket can be provided between the flanges 103 to ensure sealing performance). This structure facilitates the installation, disassembly, and routine maintenance of the multi-stage cage assembly 3. The valve cover 104 has an upper positioning seat 106 that adapts to the top contour of the multi-stage cage assembly 3, and the valve seat 105 has a lower positioning seat 107 that adapts to the bottom contour of the multi-stage cage assembly 3. A circumferential positioning structure is provided between the upper positioning seat 106 and the upper part of the multi-stage cage assembly 3, and / or between the lower positioning seat 107 and the lower part of the multi-stage cage assembly 3. In some embodiments, the circumferential positioning structure includes a positioning block extending axially and a positioning groove adapted to the positioning block. Specifically, the upper positioning bracket 106 has at least two axial positioning slots corresponding to the first-stage cage sleeve 301, the second-stage cage sleeve 302, and the third-stage cage sleeve 303, respectively. The top walls of the first-stage cage sleeve 301, the second-stage cage sleeve 302, and the third-stage cage sleeve 303 are respectively provided with axial positioning blocks adapted to the positioning slots. Alternatively, the lower positioning bracket 107 has at least two axial positioning slots corresponding to the first-stage cage sleeve 301, the second-stage cage sleeve 302, and the third-stage cage sleeve 303, respectively. The bottom walls of the first-stage cage sleeve 301, the second-stage cage sleeve 302, and the third-stage cage sleeve 303 are respectively provided with axial positioning blocks adapted to the positioning slots. During installation, the positioning blocks of each stage of the cage sleeve are aligned with the positioning slots of the corresponding brackets and engaged to complete the circumferential positioning of each stage of the cage sleeve. This ensures that the throttling grooves of each stage of the cage sleeve always maintain a preset staggered arrangement, preventing circumferential rotational displacement during operation and ensuring the stability of throttling and pressure reduction.

[0029] An annular medium flow channel is arranged around the outermost cage of the multi-stage cage assembly 3 in the valve cover 104, and the medium inlet 101 is tangentially located on this annular flow channel. The tangential inlet design allows the medium to form a uniform swirling flow after entering the valve body, which is evenly distributed around the multi-stage cage assembly 3, avoiding erosion and wear caused by excessively high local flow velocities. The medium outlet 102 is located at the bottom of the valve seat 105 and is directly connected to the inner cavity of the innermost cage of the multi-stage cage assembly 3, allowing the medium after multi-stage pressure reduction to flow smoothly out of the valve.

[0030] The multi-stage cage sleeve assembly 3 consists of a primary cage sleeve 301, a secondary cage sleeve 302, and a tertiary cage sleeve 303, which are coaxially nested from the outside in. The side walls of the primary cage sleeve 301, secondary cage sleeve 302, and tertiary cage sleeve 303 are respectively provided with a primary throttling groove 3011, a secondary throttling groove 3021, and a tertiary throttling groove 3031. After the medium enters the valve body from the medium inlet 101, it sequentially passes through the primary throttling groove 3011, the secondary throttling groove 3021, and the tertiary throttling groove 3031 for progressive throttling and pressure reduction, and finally flows out from the medium outlet 102.

[0031] Both the primary throttling channel 3011 and the secondary throttling channel 3021 are rectangular channels, arranged in multiple rows evenly along the circumference. The primary throttling channels 3011 and 3021 at the same height are staggered; that is, the position of the primary throttling channel 3011 corresponds to the solid part of the secondary cage 302, and the position of the secondary throttling channel 3021 corresponds to the solid part of the primary cage 301. This staggered arrangement design forces the medium to continuously change its flow direction as it flows through the primary and secondary cages, increasing the throttling effect. Simultaneously, it makes the pressure difference borne by each cage stage more uniform, preventing premature damage to any particular cage stage due to excessive pressure difference.

[0032] The three-stage cage sleeve 303, as the innermost cage sleeve, is the core component for achieving linear regulation. The three-stage throttling grooves 3031 are arranged in multiple segments along the axial direction of the three-stage cage sleeve 303; in this embodiment, they are divided into upper and lower groove segments. Each groove segment is arranged in six rows at equal intervals along the circumference. Adjacent groove segments are separated axially by the solid sidewalls of the three-stage cage sleeve 303, forming axial solid partition segments. The lower edge of the upper groove segment and the upper edge of the lower groove segment are axially connected, meaning the lowest point of the upper groove segment and the highest point of the lower groove segment are located on the same axial plane. All groove segments have the same width.

[0033] As valve stem 2 moves axially upward, the lower channel section is exposed first, and the effective flow area increases linearly with the rise of valve stem 2. When valve stem 2 rises to the upper edge of the lower channel section, the upper channel section just begins to be exposed. At this point, the flow area of ​​the lower channel section has reached its maximum value, and the flow area of ​​the upper channel section begins to increase linearly. Therefore, throughout the entire stroke range, the sum of the effective flow areas of each channel section always increases linearly in proportion to the opening degree of valve stem 2, thus achieving strict linear opening adjustment. At the same time, the axial solid partition section between the two channel sections acts as a natural reinforcing structure, significantly improving the structural strength of the three-stage cage sleeve 303, enabling it to withstand the effects of high pressure differential without deformation.

[0034] The valve stem 2 extends into the interior of the three-stage cage sleeve 303, with its lower end being a cylindrical section of uniform diameter, forming a fixed fitting clearance with the inner wall of the three-stage cage sleeve 303. The lower end of the valve stem 2 is rounded to reduce eddies and erosion during media flow, while also preventing the valve stem 2 from scraping against the three-stage cage sleeve 303. The upper end of the valve stem 2 receives rotational power via a connecting handwheel 202. When the handwheel 202 rotates, it drives the valve stem 2 to rotate. The valve stem 2, through an external thread on its upper section, engages with the valve stem nut 110 fixed to the top of the valve cover, converting the rotational motion into axial lifting motion.

[0035] To achieve a seal between the valve stem 2 and the valve cover 104 and prevent media leakage, a packing seat 108 is provided on the upper part of the valve cover 104. The packing seat 108 is filled with sealing packing, which is tightened by a packing gland 109 to achieve a seal. The packing gland 109 is fitted onto the valve stem 2 and fixedly connected to the valve cover 104 by multiple sets of evenly distributed bolts. The degree of packing compression can be controlled by adjusting the preload of the bolts. A valve stem nut 110 is located at the top of the central tube of the packing gland (109).

[0036] A thrust bearing 111 is also installed in the central tube of the packing gland 109 to withstand the axial thrust of the valve stem 2 and to accommodate the rotational movement of the valve stem 2, preventing excessive wear of the spring 112 due to the twisting of the valve stem. A flange 201 adapted to the opening of the central tube is formed on the valve stem 2. A spring 112 is sleeved on the valve stem 2 between the thrust bearing 111 and the flange 201. The upper and lower ends of the spring 112 are fixedly connected to the flange 201 and the thrust bearing 111, respectively. Its function is mainly reflected in the valve closing process: when the valve is opened, the upward movement of the valve stem 2 is relatively effortless due to the upward force of the medium. At this time, the spring 112 is gradually stretched and stores elastic potential energy during the upward movement of the valve stem 2. When the valve is closed, the valve stem 2 needs to move downward to resist the upward resistance of the medium. At this time, the stretched spring 112 releases its elastic potential energy to generate a restoring force, which can offset part of the medium resistance, making the downward movement of the valve stem easier and effectively reducing the operating torque of the valve.

[0037] In a preferred embodiment, an auxiliary thrust bearing may be fixedly mounted on the lower end face of the flange 201, and the upper end of the spring 112 is fixedly connected to the lower end face of the auxiliary thrust bearing 113. Through the design of the upper and lower double thrust bearings, the rotational movement of the valve stem 2 can be completely isolated from the spring 112, thoroughly preventing torsional wear of the spring, further extending the service life of the spring, and making the movement of the valve stem more stable and smooth.

[0038] The working principle of this embodiment is as follows: When the valve opening needs to be adjusted, the handwheel 202 is turned to drive the valve stem 2 to rotate. The valve stem 2 moves upward axially through the threaded engagement with the valve stem nut 110. As the valve stem 2 rises, the effective flow area of ​​the three-stage throttling groove 3031 gradually increases, and the flow rate of the medium also increases linearly. After the medium enters the valve body from the medium inlet 101, it passes through the first-stage throttling groove 3011, the second-stage throttling groove 3021, and the third-stage throttling groove 3031 in sequence for throttling and pressure reduction, and the pressure gradually decreases, finally flowing out from the medium outlet 102. Since the effective flow area of ​​the three-stage throttling groove 3031 increases linearly and directly proportionally with the opening of the valve stem 2, the flow rate of the valve also has a strict linear relationship with the opening, realizing high-precision linear regulation.

[0039] When the valve needs to be closed, the handwheel 202 is rotated in the reverse direction, causing the valve stem 2 to move downwards. The effective flow area of ​​the three-stage throttling groove 3031 gradually decreases until it is completely closed. During the valve closing process, the stretched spring 112 releases its elastic potential energy, assisting the valve stem to move downwards and offsetting some of the upward resistance of the medium, making the valve closing operation easier. Throughout the entire opening and closing process, the axial solid partition section always provides sufficient structural strength for the three-stage cage sleeve 303, ensuring the safe and reliable operation of the valve under high-pressure conditions.

[0040] The above description is merely a preferred embodiment of the present invention and is not intended to limit the scope of protection of the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A multi-stage pressure-reducing cage-type throttle valve, comprising a valve body (1) and a valve stem (2), wherein a multi-stage cage assembly (3) is provided between the medium inlet (101) and the medium outlet (102) of the valve body (1) and is coaxially nested from the outside to the inside, and the valve stem (2) extends into the innermost cage of the multi-stage cage assembly (3), characterized in that: The throttling grooves of the innermost cage are distributed along the axial direction with equal flow area increments, so that the effective flow area increment remains constant for each unit stroke of the valve core (2) moving axially, thereby realizing the linear opening adjustment of the multi-stage cage assembly (3).

2. The multi-stage pressure-reducing cage-type throttle valve according to claim 1, characterized in that: The multi-stage cage assembly (3) includes a first-stage cage (301), a second-stage cage (302), and a third-stage cage (303) coaxially nested from the outside to the inside. A first-stage throttling groove (3011), a second-stage throttling groove (3021), and a third-stage throttling groove (3031) are respectively provided on the first-stage cage (301), the second-stage cage (302), and the third-stage cage (303).

3. The multi-stage pressure-reducing cage-type throttle valve according to claim 2, characterized in that: The primary throttling channel (3011) and the secondary throttling channel (3021) are arranged in multiple rows in the circumferential direction, and the primary throttling channel (3011) and the secondary throttling channel (3021) at the same height are arranged in a staggered manner.

4. The multi-stage pressure-reducing cage-type throttle valve according to claim 3, characterized in that: The three-stage throttling groove (3031) is arranged in a multi-layer segmented manner along the axial direction of the three-stage cage (303). Each layer of groove is arranged at equal intervals along the circumferential direction, and adjacent layers of groove are separated by the side wall solid of the three-stage cage (303) along the axial direction. The lower edge of the upper layer groove is connected to the upper edge of the lower layer groove in the axial direction. When the valve stem (2) moves upward, the sum of the effective flow areas of each layer of groove increases linearly in proportion to the valve stem opening.

5. The multi-stage pressure-reducing cage-type throttle valve according to claims 1-4, characterized in that: The valve body (1) adopts a split structure, including a valve cover (104) and a valve seat (105) that can be detachably connected by a flange (103). The valve cover (104) is provided with an upper positioning seat (106) on the top contour of the multi-stage cage assembly (3), and the valve seat (105) is provided with a lower positioning seat (107) on the bottom contour of the multi-stage cage assembly (3). A medium flow channel is arranged around the outermost cage of the multi-stage cage assembly (3) in the valve cover (104), and a medium inlet (101) is provided tangentially in the medium flow channel. A medium outlet (102) communicating with the inner cavity of the innermost cage is provided at the bottom of the valve cover (105).

6. The multi-stage pressure-reducing cage-type throttle valve according to claim 5, characterized in that: The valve cover (103) is also provided with a packing seat (108) for sealing connection.

7. The multi-stage pressure-reducing cage-type throttle valve according to claim 7, characterized in that: The packing seat (108) is sleeved with the valve stem (2) through the packing gland (109).

8. The multi-stage pressure-reducing cage-type throttle valve according to claim 8, characterized in that: A valve stem nut (110) is provided on the central tube of the packing gland (109), and the valve stem (2) is screwed into the valve stem nut (110) through the thread on the upper section.

9. The multi-stage pressure-reducing cage-type throttle valve according to claim 9, characterized in that: A thrust bearing (110) is installed in the central tube of the pressure cap (109). A flange (201) adapted to the opening of the central tube is formed on the valve stem (2). A spring (111) is sleeved on the valve stem (2) of the thrust bearing (110) and the flange (201). The upper and lower ends of the spring (111) are fixedly connected to the flange (201) and the thrust bearing (110) respectively.

10. The multi-stage pressure-reducing cage-type throttle valve according to claim 1 or 9, characterized in that: The upper end of the valve stem (2) receives rotational power through a connecting handwheel (202), and the lower end of the valve stem (2) is rounded.

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