Flow control device and regulation system suitable for high purity piping

Abstract

This invention relates to the field of valve technology and discloses a flow control device suitable for high-purity pipelines. The device includes a valve body, a valve stem seat connected to the valve body, a valve stem axially movable within the valve stem seat, and a handle for driving the valve stem. The valve body has a fluid inlet and a fluid outlet. An independent sleeve is provided within the valve cavity of the valve body, and the sleeve has a throttling orifice at its center. The end of the valve stem has a needle-shaped portion extending into the throttling orifice. The sleeve is supported on the valve body by a sealing ring. This invention achieves clean, particulate-free micro-flow control through a modular design of the independent sleeve and elastic sealing ring. Furthermore, the thermal compensation mechanism ensures stable regulation characteristics over a wide temperature range, avoiding temperature drift. The overall structure is reliably sealed, provides precise regulation, and is easy to maintain. It meets the stringent requirements of high-purity pipelines for flow control, extends equipment lifespan, and reduces overall costs.

Description

Technical Field

[0001] This invention relates to the field of valve technology, specifically to a flow control device and regulating system suitable for high-purity pipelines. Background Technology

[0002] In high-purity pipeline systems, the control of fluid flow, especially the precise and stable regulation of micro-flow rates (such as CV values ​​as low as 0.004), places extremely high demands on the system. This system not only requires valves to possess excellent regulating characteristics, but also necessitates ensuring that no particulate contaminants are generated throughout the regulation process to avoid contaminating high-value production fluids.

[0003] In existing technologies, needle valves are commonly used as key components for micro-flow regulation. Traditional needle valves typically have the critical throttling orifice directly machined onto the valve body, with the needle-shaped portion at the front end of the valve stem engaging with this orifice to adjust the flow area. This integrated structure has the following inherent drawbacks that are difficult to overcome:

[0004] 1. Extremely high processing difficulty and cost: In order to achieve micro-flow control, the size and form and position tolerance requirements of the throttling orifice are very strict. Precision machining of deep and long micro-holes on the valve body is very difficult, and the subsequent online measurement methods are limited, resulting in low part processing yield and high cost.

[0005] 2. Difficulty in ensuring coaxiality and unstable regulation performance: The linearity and repeatability of flow regulation are highly dependent on the precise alignment of the valve stem needle tip and the valve body throttling orifice. Traditional structures require multiple assembly steps such as valve body, valve stem seat, and valve stem to transmit and ensure coaxiality. Accumulated errors can easily lead to problems such as inaccurate zero-point flow, nonlinear flow curve and poor regulation repeatability.

[0006] 3. Wear and tear generates particulate contaminants: During regulation, especially when approaching the zero position, the valve stem needle tip will inevitably come into contact with the edge of the throttling orifice. In a rigid support structure, this contact will lead to friction and wear between metals, continuously generating particulate matter that contaminates the fluid. At the same time, wear will change the key fit dimensions, causing the valve flow characteristics to drift and shortening the product life.

[0007] 4. Poor maintainability and low economy: Once the key throttling orifice directly machined on the valve body fails due to wear or machining defects, it is usually impossible to repair it alone. The entire valve body must be replaced, resulting in high maintenance costs and waste of resources.

[0008] Therefore, there is an urgent need in this field for an innovative flow control device that can fundamentally resolve the contradiction between precision machining, long-term performance stability, and cleanliness assurance in high-purity application scenarios. Summary of the Invention

[0009] The purpose of this invention is to overcome the shortcomings of existing technologies and provide a flow control device suitable for high-purity pipelines. This device, through modular and flexible unloading design, separates the precision throttling function from the valve body, effectively decoupling processing and assembly difficulties, and avoiding hard friction between metals during zero-position adjustment. This simultaneously achieves high-precision micro-flow control, ultra-long lifespan, and extremely high fluid cleanliness.

[0010] This invention proposes a flow control device suitable for high-purity pipelines, comprising a valve body, a valve stem seat connected to the valve body, a valve stem axially movable within the valve stem seat, and a handle for driving the valve stem. The valve body has a fluid inlet and a fluid outlet. An independent sleeve is provided within the valve cavity of the valve body, and a throttling orifice is provided at the center of the sleeve. The end of the valve stem has a needle-shaped portion extending into the throttling orifice. The sleeve is supported on the valve body by a sealing ring, which is configured to elastically deform when the valve stem moves relative to the sleeve to a zero position to buffer the contact between the valve stem and the sleeve.

[0011] The independent sleeve separates the precision throttling orifice from the valve body and can be manufactured using specialized precision machining processes, reducing processing difficulty and cost, and improving the dimensional accuracy and consistency of the throttling orifice. The needle-shaped part cooperates with the throttling orifice to achieve precise micro-flow adjustment. The elastic deformation of the sealing ring forms a buffer at the zero point, avoiding wear and particulate contamination caused by hard contact between metals, ensuring fluid cleanliness. The elastically supported sleeve has self-adaptability, which can compensate for minor coaxiality errors and improve the linearity and repeatability of flow regulation.

[0012] As a further optimization of the present invention, the sealing ring is an annular component made of polytetrafluoroethylene or perfluoroether rubber. Both polytetrafluoroethylene and perfluoroether rubber have low elastic modulus, high temperature resistance, and corrosion resistance, making them suitable for the fluid medium and working environment of high-purity pipelines. The elasticity of the material itself ensures the buffering effect at the zero point position, avoiding wear. It has strong chemical stability, does not react with the fluid, and does not release pollutants, thus ensuring the purity of the fluid.

[0013] As a further optimization of the present invention, the sleeve and the sealing ring are separate structures, and together they form a flow channel module that can be disassembled as a whole. The separate structure facilitates individual processing and assembly, ensuring the precision of each component. The flow channel module that can be disassembled as a whole makes maintenance more convenient. When the throttling orifice is worn or fails, it is not necessary to replace the entire valve body, but only the module needs to be replaced, which greatly reduces maintenance costs and downtime, and improves the economy of the equipment.

[0014] As a further optimization of the present invention, the flow channel module is fixed and sealed at the bottom of the valve cavity of the valve body by means of a valve stem seat and a sealing ring. The valve stem seat and the sealing ring cooperate to firmly fix the flow channel module, so as to avoid the module displacement during operation and affect the adjustment accuracy. The sealing ring ensures the sealing between the module and the valve body, prevents fluid leakage or short circuit, ensures the accuracy of flow control, and avoids contamination.

[0015] As a further optimization of the present invention, the lower end of the sleeve is integrally formed or connected with an extension tube. The channel of the extension tube is coaxially connected with the throttling orifice, which can guide the fluid to flow stably, reduce flow field disturbance, and improve the stability of flow regulation. The extension tube extends the throttling channel, further optimizes the micro-flow control effect, and at the same time plays an auxiliary guiding role for the needle-shaped part, avoiding its deviation and wear.

[0016] As a further optimization of the present invention, it also includes a thermal compensation mechanism disposed in the valve body and located between the valve stem seat and the sleeve. The thermal compensation mechanism responds to temperature changes and drives the sleeve to generate a compensation displacement that is opposite in direction and equal in magnitude to the axial displacement of the valve stem caused by thermal expansion.

[0017] The thermal compensation mechanism counteracts the relative axial displacement between the valve stem and sleeve caused by temperature changes, ensuring that the zero-point flow rate and regulation characteristics remain stable over a wide temperature range, avoiding flow drift caused by temperature fluctuations, meeting the stringent process stability requirements of high-purity pipelines, and expanding the applicable operating conditions of the device.

[0018] As a further optimization of the present invention, the thermal compensation mechanism includes: a first balance ring fixedly connected to the valve body, which is connected to the valve stem via a first threaded pair;

[0019] The second balance ring, which is connected to the sleeve drive, is connected to the valve stem via a second threaded pair, and the direction of rotation of the second threaded pair is opposite to that of the first threaded pair;

[0020] A preload spring is provided between the first balance ring and the second balance ring;

[0021] The second balance ring is constrained to prevent rotation relative to the valve body;

[0022] The screw pairs with opposite rotation and preload springs utilize the thermal expansion differences of the components during temperature changes to trigger compensation action, ensuring precise transmission. The rotational constraint of the second balance ring ensures that the compensation displacement is transmitted axially, achieving precise compensation movement of the sleeve. The structure is compact, requires no additional power source, achieves passive automatic thermal compensation, and has high reliability.

[0023] As a further optimization of the present invention, the pitch of the first threaded pair and the second threaded pair are equal. The equal pitch ensures that the axial displacement generated by the thermal expansion of the valve stem can be accurately converted into the reverse compensation displacement of the sleeve through the threaded pair, ensuring that the compensation amount is equal to the displacement amount, achieving complete compensation. Pitch matching makes the transmission ratio stable, improves the accuracy and consistency of thermal compensation, and ensures stable adjustment characteristics in a wide temperature range.

[0024] As a further optimization of the present invention, the valve body has an axially extending guide groove on the inner wall of the valve cavity, and a guide block that cooperates with the guide groove on the second balance ring. The guide groove and the guide block cooperate to restrict the rotation of the second balance ring, ensuring that it can only move along the axial direction, thus ensuring the normal operation of the thermal compensation mechanism. The guide structure improves the stability and accuracy of the movement of the second balance ring, avoids compensation errors caused by offset, and further enhances the thermal compensation effect.

[0025] A flow regulation system suitable for high-purity pipelines is provided. The system integrates the aforementioned flow control device and has advantages such as high-precision micro-flow control, cleanliness and pollution-free operation, and stable operation over a wide temperature range. It can be directly adapted to the fluid control requirements of high-purity pipelines without additional modifications, thereby improving the overall reliability and practicality of the system. It is suitable for fields such as semiconductors and biomedicine, which have extremely high requirements for fluid purity and flow stability.

[0026] The flow control device and regulating system for high-purity pipelines proposed in this invention have the following beneficial effects:

[0027] (i) This invention transfers the most precise throttling orifice from the valve body to an independent sleeve part. As an independent small part, the sleeve can use better materials and more efficient precision machining (such as wire EDM, micro-hole drilling, etc.) and inspection methods, which greatly reduces the processing difficulty, improves the yield and consistency, and reduces the overall cost.

[0028] (ii) The sealing ring elastic support sleeve made of low elastic modulus material such as PTFE forms a buffer suspension system during zero-position adjustment. When the valve stem approaches the upper end face of the sleeve, the outer circle of the upper end of the needle part contacts the upper end face of the sleeve. Most of the contact stress is absorbed by the elastic deformation of the sealing ring. The actual contact force acting on the mating surface between the needle part and the throttling orifice is very small, which fundamentally avoids the severe friction and scraping between metals and completely eliminates the problem of particulate contaminants caused by wear.

[0029] (iii) The elastic support sleeve has a certain degree of self-adaptability, which can compensate for the small alignment error between the valve stem and the throttling orifice of the sleeve to a certain extent, making the fit between the needle part and the throttling orifice smoother. This effectively improves the linearity and repeatability of flow regulation, and ensures the stability and accuracy of micro-flow control.

[0030] (iv) By setting up a thermal compensation mechanism consisting of threaded pairs with different directions and preload springs, the axial relative displacement caused by temperature changes due to the different thermal expansion coefficients of the valve stem and valve body materials can be actively offset. This design ensures the extreme stability of the valve's zero flow rate and regulation characteristics under wide temperature range conditions, meeting more stringent process requirements.

[0031] (v) As independent vulnerable modules, the sleeve and sealing ring can be replaced or maintained without replacing the expensive valve body, which greatly reduces maintenance costs and time.

[0032] Additional aspects and advantages of the invention will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. Attached Figure Description

[0033] Figure 1 This is a schematic diagram of the overall structure of Embodiment 1 provided by the present invention;

[0034] Figure 2 This is a three-dimensional cross-sectional structural diagram of Embodiment 1 provided by the present invention;

[0035] Figure 3 This is a front cross-sectional view of Embodiment 1 provided by the present invention;

[0036] Figure 4 This is a schematic diagram of the sleeve and sealing ring in Embodiment 1 of the present invention;

[0037] Figure 5 This is a front cross-sectional view of Embodiment 2 provided by the present invention.

[0038] Figure Descriptions: 1. Valve body; 2. Inlet end; 3. Outlet end; 4. Valve stem seat; 5. Handle; 6. Valve stem; 7. Set screw; 8. Sealing ring; 9. Sleeve; 10. Needle-shaped part; 11. Flow hole; 12. Second flow channel; 13. Sealing ring; 14. Sealing ring; 15. Locking screw; 16. Annular groove; 17. Annular sealing groove; 18. Extension tube; 19. First balance ring; 20. Second balance ring; 21. Compression sleeve; 22. Preload spring; 23. Guide groove; 24. Guide block. Detailed Implementation

[0039] Embodiments of the present invention are described in detail below. Examples of these embodiments are illustrated in the accompanying drawings, wherein the same or similar symbols 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 are only used to explain the present invention, and should not be construed as limiting the present invention.

[0040] In this invention, unless otherwise explicitly specified and limited, "above" or "below" the second feature can mean that the first feature is in direct contact with the second feature, or that the first feature is in indirect contact with the second feature through an intermediate medium. Furthermore, "above," "over," and "on top" of the second feature can mean that the first feature is directly above or diagonally above the second feature, or simply that the first feature is at a higher horizontal level than the second feature. "Below," "below," and "under" the second feature can mean that the first feature is directly below or diagonally below the second feature, or simply that the first feature is at a lower horizontal level than the second feature.

[0041] Example 1

[0042] Please see Figures 1-4 The flow control device and regulating system for high-purity pipelines proposed in this invention include a valve body 1, with an inlet end 2 and an outlet end 3 on both sides of the valve body 1. A first flow channel extending vertically downward and communicating with the inlet end 2 is located at the center of the bottom surface of the valve cavity of the valve body 1. A second flow channel 12 located on the side of the first flow channel and communicating with the outlet end 3 is opened on the bottom surface of the valve cavity of the valve body 1. Fluid enters the valve cavity through the inlet end 2 and the first flow channel, and then flows out through the second flow channel 12 and the outlet end 3.

[0043] The valve body 1 has an upward-facing valve cavity opening and is fitted with a valve stem seat 4. A handle 5 is movably fitted onto the upper end of the valve stem seat 4. A valve stem 6 is provided inside the valve stem seat 4. The upper end of the valve stem 6 is threadedly connected to the upper end of the valve stem seat 4 and locked to the handle 5 by a set screw 7. The lower end of the valve stem 6 extends to the lower part of the valve stem seat 4 and has an integrally formed needle-shaped part 10. The needle-shaped part 10 has a 1° needle tip. The needle-shaped part 10 is aligned with the first flow channel and is fitted with a gap.

[0044] Specifically, a sealing ring 8 and a sleeve 9 are installed at the bottom of the valve cavity of the valve body 1. The sleeve 9 is installed inside the sealing ring 8 and its upper end face is flush. Both the sealing ring 8 and the sleeve 9 are provided with coaxially arranged and vertically connected flow holes 11. The upper and lower ends of the flow holes 11 are respectively connected to the valve cavity of the valve body 1 and the upper opening of the second flow channel 12. A throttling orifice is provided at the center of the sleeve 9, which connects the first flow channel and the valve cavity. The throttling orifice is adapted to the inclination of the outer wall of the needle-shaped part 10. The needle-shaped part 10 extends from top to bottom through the throttling orifice and into the first flow channel. There is a gap between the needle-shaped part 10 and the inner wall of the first flow channel to prevent damage.

[0045] In use, by rotating the handle 5, the valve stem 6 drives the needle part 10 to rise and fall, thereby changing the size of the gap between the front cone surface of the needle part 10 and the inner wall of the throttling orifice. The larger the gap, the larger the opening and the more flow; the smaller the gap, the smaller the opening and the less flow, thus realizing the opening and closing of the valve and flow control.

[0046] When the valve stem 6 is adjusted to the zero position, the upper end of the needle-shaped part 10 is in close contact with the inner wall of the upper end of the throttling orifice, but there will be a small flow gap. There is also a gap between the lower end face of the valve stem 6 and the upper end face of the sleeve 9 to prevent damage caused by direct contact. At this time, the sealing pressure ring 8 is deformed to avoid wear between the needle-shaped part 10 and the throttling orifice, which would generate particulate matter.

[0047] Furthermore, an annular sealing groove 17 is provided at the lower end of the valve stem seat 4, and a sealing ring 13 is installed in the annular sealing groove 17. The lower end of the sealing ring 14 forms an annular cavity by pressing the sealing ring 13 against the joint between the sealing pressure ring 8 and the upper end face of the sleeve 9, which can prevent fluid leakage. At the same time, the sealing pressure ring 8 can also prevent internal leakage. The fluid in the needle cavity enters the annular cavity and then flows out through the flow hole 11 and the second flow channel 12.

[0048] Furthermore, the lower end of the valve stem 6 has an annular groove 16 on its outer periphery, and a sealing ring 14 is installed in the annular groove 16. The outer circular surface of the sealing ring 14 is in close contact with the inner wall of the valve stem seat 4 to form a seal and prevent the fluid in the annular cavity from flowing upward.

[0049] Specifically, such as Figure 4 As shown, the sealing ring 8 has an annular wall extending upward on its outer periphery for mounting the sleeve 9. A through hole is provided at the center of the sealing ring 8. An extension tube 18 is installed at the center of the lower end of the sleeve 9, which is aligned with and connected to the throttling orifice. The lower end of the extension tube 18 passes through the through hole and extends to the bottom of the sealing ring 8. The lower end of the needle-shaped part 10 passes through the throttling orifice and the extension tube 18 in sequence.

[0050] The core of this embodiment lies in simultaneously achieving precise flow control and preventing particulate matter contamination, as detailed below:

[0051] Fluid enters from inlet 2, flows upward into the valve cavity through the first flow channel at the bottom of the valve body, flows through the precision throttling orifice in the center of sleeve 9 and the extension tube 18 below it, enters the second flow channel 12, and finally exits from outlet 3. The needle-shaped part 10 and the throttling orifice of sleeve 9 form a precision throttling pair. By rotating the handle 5, the valve stem 6 generates axial displacement, which drives the needle-shaped part 10 to rise and fall within the throttling orifice. When the needle-shaped part 10 descends, the annular flow area between its conical surface and the inner wall of the throttling orifice decreases, the flow resistance increases, and the flow rate decreases until it is close to closing. Conversely, the flow rate increases. This adjustment method based on the cone-throttling orifice gap can achieve extremely precise micro-flow control.

[0052] In traditional needle valves, the tip of the valve needle will rigidly contact and squeeze the valve seat when closed, inevitably leading to wear. However, in actual use, when adjusted to the zero position and close to the closed position, the tip of the needle-shaped part 10 does not contact the throttling orifice. Instead, the lower end face of the valve stem 6 approaches or contacts the upper end face of the sleeve 9. The sealing ring 8 is made of a non-metallic material with a low elastic modulus, such as polytetrafluoroethylene or perfluoroether rubber. It supports the sleeve 9. When adjusted to the zero position, the sealing ring 8 will produce a slight elastic deformation. This deformation process plays a role in buffering and unloading, absorbing contact energy and avoiding hard impact between metals. Most of the contact stress is absorbed by the elastomer. The actual contact force acting on the throttling orifice of the sleeve 9 and the needle-shaped part 10 is very small, thereby greatly suppressing friction and scratching and fundamentally preventing the generation of particulate matter.

[0053] The sealing ring 13 is pressed against the upper end face joint of the sealing ring 8 and the sleeve 9 to ensure that all fluid must flow through the sleeve throttling orifice, preventing fluid from short-circuiting and leaking from the joint. The valve stem sealing ring 14 prevents fluid from leaking upward along the valve stem 6, thus achieving dynamic sealing of the valve stem.

[0054] In summary, this embodiment solves the problems of precision machining and particulate matter contamination through two major designs: independent sleeve and elastic unloading, making it suitable for high-purity environments with stable operating conditions.

[0055] Example 1 can solve the wear and particulate matter problems at room temperature. However, in high-purity processes, the fluid in the pipeline may have different temperatures, or the ambient temperature may change. Due to the different coefficients of thermal expansion of the metal valve stem 6, needle part 10, and valve body 1, and the non-metallic sealing ring 8 and sleeve 9, the elongation of the valve stem 6, needle part 10, and valve body 1 differs when the temperature rises. This causes a slight change in the relative axial position of the needle part 10 and the throttling orifice, even if the rotation position of the handle 5 remains unchanged. This change is sufficient to cause a significant drift in the zero flow rate of micro-flow control, affecting process stability. Moreover, temperature changes may also cause changes in the preload of the sealing ring, affecting its sealing performance and elastic unloading effect. Therefore, Example 2 is proposed, as follows:

[0056] Example 2

[0057] It illustrates yet another embodiment of the invention based on Embodiment 1;

[0058] like Figure 5As shown, the valve stem seat 4 is fixedly installed on the upper end face of the valve body 1 and is coaxially aligned with the valve cavity. The valve cavity of the valve body 1 is provided with a first balance ring 19, a second balance ring 20 and a compression sleeve 21 from top to bottom. The first balance ring 19 and the second balance ring 20 are abutted by a pre-tightening spring 22. The second balance ring 20 is fixedly connected to the compression sleeve 21. The lower end of the compression sleeve 21 presses the sealing ring 13 onto the upper end joint of the sealing ring 8 and the sleeve 9.

[0059] The first balance ring 19 is fixed to the upper opening of the valve body 1 by fasteners. The outer walls of the second balance ring 20 and the clamping sleeve 21 are slidably connected to the inner wall of the valve cavity of the valve body 1. The inner wall of the valve cavity is provided with a plurality of circumferentially distributed and axially extended guide grooves 23. The outer wall of the second balance ring 20 is equipped with a plurality of guide blocks 24 corresponding one-to-one with the number and position of the guide grooves 23. The guide blocks 24 are axially slidably assembled in the guide grooves 23. The inner holes of the first balance ring 19 and the second balance ring 20 are both threaded holes with equal pitch and opposite directions of rotation.

[0060] Both the first balancing ring 19 and the second balancing ring 20 are low-expansion alloys such as Invar alloy rings.

[0061] The thermal compensation process in this embodiment (taking temperature rise as an example) is as follows:

[0062] Step 1: Component Deformation

[0063] When the valve body 1 is heated, it expands. Since its lower end is fixed, the whole body will stretch upward. Because the first balance ring 19 is fixed to the valve body 1, the first balance ring 19 will also move upward by a displacement ΔL1.

[0064] When the valve stem 6 is heated, it expands. Since its upper end is constrained by the valve stem seat 4, the whole will extend downward, causing the needle part 10 to move downward by a displacement ΔL2.

[0065] Step Two: Compensation Mechanism Triggered

[0066] The valve body 1 extends upward, causing the first balance ring 19 fixed at its upper end to move upward by ΔL1. The upward movement of the first balance ring 19 is transmitted to the valve stem 6 through the first threaded pair (left-handed). Since the valve stem 6 is constrained and cannot rotate, this upward movement will force the valve stem 6 to rotate slightly clockwise.

[0067] The clockwise rotation of valve stem 6 is transmitted to the second balance ring 20 through the second threaded pair (right-hand thread). Since the second balance ring 20 is restricted from rotating by the guide groove, according to the characteristics of the right-hand thread, the clockwise rotation of valve stem 6 will drive the second balance ring 20 to move downward.

[0068] Step 3: Displacement Transfer and Cancellation

[0069] The second balance ring 20 moves downward and, through the compression sleeve 21, ultimately transmits the downward displacement ΔL3 to the sealing ring 13 and the entire sleeve 9 assembly;

[0070] Similarly, by designing ΔL3=ΔL2, the downward displacement of the sleeve 9 and the needle-shaped part 10 is consistent, maintaining relative position stability and eliminating zero-position drift.

[0071] In summary, this invention, through its modular design of independent sleeves and elastic sealing rings, solves the pain points of traditional devices, such as difficult processing, easy wear, and high maintenance costs. It achieves clean, particulate-free micro-flow control, and the thermal compensation mechanism ensures stable regulation characteristics over a wide temperature range, avoiding temperature drift. The overall structure is reliably sealed, precisely regulated, and conveniently maintained, meeting the stringent requirements of high-purity pipelines for flow control, extending equipment lifespan, reducing overall costs, and adapting to high-precision fluid control scenarios in multiple fields.

[0072] The above description is only a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any equivalent substitutions or modifications made by those skilled in the art within the scope of the technology disclosed in the present invention, based on the technical solution and inventive concept of the present invention, should be covered within the scope of protection of the present invention.

Claims

1. A flow control device suitable for high-purity pipelines, comprising a valve body (1), a valve stem seat (4) connected to the valve body (1), a valve stem (6) axially movable within the valve stem seat (4), and a handle (5) for driving the valve stem (6), wherein the valve body (1) has a fluid inlet and a fluid outlet, characterized in that: The valve body (1) has an independent sleeve (9) inside its valve cavity, and the sleeve (9) has a throttling orifice at its center. The valve stem (6) has a needle-shaped part (10) at its end that extends into the throttling orifice. The sleeve (9) is supported on the valve body (1) by a sealing ring (8), which is configured to elastically deform when the valve stem (6) moves relative to the sleeve (9) to a zero position to buffer the contact between the valve stem (6) and the sleeve (9). It also includes a thermal compensation mechanism disposed in the valve body (1) and located between the valve stem seat (4) and the sleeve (9). The thermal compensation mechanism responds to temperature changes and drives the sleeve (9) to generate a compensation displacement that is opposite in direction and equal in magnitude to the axial displacement generated by the valve stem (6) due to thermal expansion. The thermal compensation mechanism includes: A first balance ring (19) is fixedly connected to the valve body (1), and is connected to the valve stem (6) via a first threaded pair; The second balance ring (20) is connected to the sleeve (9) via a transmission, and is connected to the valve stem (6) via a second threaded pair, wherein the direction of rotation of the second threaded pair is opposite to that of the first threaded pair; A preload spring (22) is provided between the first balance ring (19) and the second balance ring (20); The second balance ring (20) is constrained from rotating relative to the valve body (1); The first threaded pair and the second threaded pair have the same pitch; The valve body (1) has an axially extending guide groove (23) on the inner wall of the valve cavity, and the second balance ring (20) has a guide block (24) that cooperates with the guide groove (23).

2. The flow control device suitable for high-purity pipelines according to claim 1, characterized in that, The sealing ring (8) is an annular component made of polytetrafluoroethylene or perfluoroether rubber.

3. The flow control device suitable for high-purity pipelines according to claim 1, characterized in that, The sleeve (9) and the sealing ring (8) are separate structures, and together they form a flow channel module that can be disassembled as a whole.

4. A flow control device suitable for high-purity pipelines according to claim 3, characterized in that, The flow channel module is fixed and sealed at the bottom of the valve cavity of the valve body (1) by means of the valve stem seat (4) and the sealing ring (13).

5. A flow control device suitable for high-purity pipelines according to claim 1, characterized in that, The lower end of the sleeve (9) is integrally formed or connected to an extension tube (18), the channel of which is coaxially connected to the throttling orifice.

6. A flow regulation system suitable for high-purity pipelines, characterized in that, The system integrates a flow control device as described in any one of claims 1-5.

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