Low-leakage high-precision bellows regulating valve
Patent Information
- Application Number
- PCT/CN2026/101116
- Authority / Receiving Office
- WO · WO
- Patent Type
- Applications
- Current Assignee / Owner
- Priority Date
- 2025-08-20
- Filing Date
- 2026-06-03
- Publication Date
- 2026-10-22
Smart Images
Figure CN2026101116_22102026_PF_FP_ABST
Abstract
Description
A low-emission, high-precision bellows regulating valve Technical Field
[0001] This invention relates to the field of control valve technology, and in particular to a low-emission, high-precision bellows control valve. Background Technology
[0002] In modern industrial process automation systems, control valves, as key actuators, achieve precise control of parameters such as flow rate and pressure by changing the cross-sectional area of the fluid passage. Bellows control valves, with their unique sealing structure, achieve zero leakage at the valve stem by replacing traditional stuffing boxes with bellows, making them the preferred equipment for handling toxic, flammable, and corrosive media.
[0003] In existing technologies, bellows, as the core sealing element, are highly susceptible to fatigue failure due to the long-term exposure to medium pressure and mechanical stress generated by the reciprocating motion of the valve stem. To extend its service life, a design approach that increases the axial length of the bellows is typically adopted, reducing fatigue by decreasing the relative compression per unit stroke. However, excessively long bellows require matching extra-long valve stems, resulting in a significant increase in the overall axial dimension of the valve and occupying more installation space. Furthermore, the reduced stiffness of the extra-long valve stem makes it prone to bending deformation under fluid impact and frequent operation, leading to decreased valve positioning accuracy and control deviations. Summary of the Invention
[0004] Therefore, it is necessary to provide a low-emission, high-precision bellows control valve to address the problem of bellows being prone to fatigue failure after long-term use in current bellows control valves.
[0005] The above objectives are achieved through the following technical solutions:
[0006] A low-emission, high-precision bellows regulating valve includes a valve body, a plug, a valve stem, and a sealing mechanism. The valve body has an inlet and an outlet, which are connected within the valve body via a through-hole. The plug is slidably disposed within the valve body and serves to seal the through-hole. One end of the valve stem is connected to the plug, and the other end of the valve stem passes through the valve body and is located outside the valve body, with the valve stem slidably connected to the valve body. The sealing mechanism includes an Ω-shaped bellows, a U-shaped bellows, a connector, and an adjusting assembly. Both the Ω-shaped and U-shaped bellows are sleeved on the valve stem and located within the valve body. Inside the valve body, a connector is mounted on the valve stem and is used to connect the Ω-shaped bellows and the U-shaped bellows. The Ω-shaped bellows, the U-shaped bellows, and the connector together isolate the valve stem portion located inside the valve body from the medium inside the valve body. When the valve stem slides on the valve body, the adjusting component controls the relative position of the connector on the valve stem, so that when the through hole is open, the contraction of each bellows of the Ω-shaped bellows is greater than the contraction of each bellows of the U-shaped bellows; when the through hole is closed, the elongation of each bellows of the Ω-shaped bellows is less than the elongation of each bellows of the U-shaped bellows.
[0007] Preferably, the valve stem and sealing mechanism located within the valve body are both situated in the liquid outlet.
[0008] Preferably, the connector is cylindrical, with a first boss extending outward in its radial direction at one end and a second boss extending inward in its radial direction at the other end. The connector is coaxial with the valve stem. An Ω-shaped bellows is sleeved on the connector, with one end connected to the first boss and the other end connected to the valve body. A U-shaped bellows is located between the connector and the valve stem, with one end connected to the plug and the other end connected to the second boss.
[0009] Preferably, the first protrusion is closer to the block than the second protrusion.
[0010] Preferably, the adjusting assembly includes a rotating cylinder, a first slider, and a second slider. The rotating cylinder is sleeved on the valve stem located inside the valve body and is rotatably connected to the valve stem. The rotating cylinder has a first spiral groove, a second spiral groove, and a third spiral groove arranged sequentially along the axial direction of the valve stem with the same direction of rotation and decreasing pitch in sequence. The second spiral groove and the third spiral groove are connected end to end. The first slider is fixedly disposed in the valve body and slides in the first spiral groove. The pitch of the second spiral groove is greater than half of the pitch of the first spiral groove, and the pitch of the third spiral groove is less than half of the pitch of the first spiral groove. The second slider slides in the second spiral groove or the third spiral groove and is connected to the connecting member.
[0011] Preferably, the second boss is sleeved on the rotating drum and slidably connected to the rotating drum, and the U-shaped bellows is slidably connected to the rotating drum.
[0012] Preferably, when the through hole is opened halfway, the Ω-shaped bellows and the U-shaped bellows are at their natural lengths, while the second slider is located at the junction of the second spiral groove and the third spiral groove.
[0013] Preferably, both the Ω-shaped bellows and the U-shaped bellows are provided with flanges at their ends. The Ω-shaped bellows are connected to the valve body and the first boss respectively through the flanges, and the U-shaped bellows are connected to the plug and the second boss respectively through the flanges.
[0014] Preferably, the connector is provided with multiple guide rods, which are arranged around the circumference of the connector, and the end of each guide rod away from the connector is slidably connected to the valve body.
[0015] Preferably, the low-emission, high-precision bellows control valve also includes a drive mechanism for driving the valve stem to slide along its axial direction.
[0016] The beneficial effects of this invention are as follows: The corrugated shape of the Ω-shaped bellows is close to the letter Ω, and its corrugation depth is relatively shallow. The shallower corrugation shape allows for a relatively large contact area between the corrugations during compression, enabling more uniform pressure distribution. This reduces local stress concentration, lowers the risk of fatigue cracks caused by stress concentration, and improves durability under compression conditions. The U-shaped bellows, on the other hand, has a deeper corrugation shape and a larger radius of curvature. During tension, the openings of the corrugations can better disperse stress, avoiding stress... Concentrating too much at the root of the corrugations reduces the risk of fatigue crack initiation. Through the coordinated design of connectors and adjustment components, when both Ω-shaped and U-shaped corrugated pipes contract, the contraction amount of the Ω-shaped corrugated pipe can be increased while the contraction amount of the U-shaped corrugated pipe is decreased, reducing the stress on the U-shaped corrugated pipe and extending its service life. Simultaneously, when both Ω-shaped and U-shaped corrugated pipes elongate, the elongation amount of the Ω-shaped corrugated pipe can be decreased while the elongation amount of the U-shaped corrugated pipe is increased, reducing the stress on the Ω-shaped corrugated pipe and extending its service life. Attached Figure Description
[0017] Figure 1 is a schematic diagram of a low-emission, high-precision bellows regulating valve provided in an embodiment of the present invention.
[0018] Figure 2 is a cross-sectional view of a low-emission, high-precision bellows regulating valve provided in an embodiment of the present invention;
[0019] Figure 3 is an enlarged view of point A in Figure 2;
[0020] Figure 4 is a structural schematic diagram of a connector for a low-emission, high-precision bellows regulating valve provided in an embodiment of the present invention.
[0021] Figure 5 is a schematic diagram of the rotary cylinder structure of a low-emission, high-precision bellows regulating valve provided in an embodiment of the present invention;
[0022] Figure 6 is a front view of the rotary drum of a low-emission, high-precision bellows regulating valve provided in an embodiment of the present invention.
[0023] in:
[0024] 100. Valve body; 101. Plug; 102. Valve stem; 103. Liquid inlet; 104. Liquid outlet; 105. Ω-shaped bellows; 106. U-shaped bellows; 107. Connector; 108. First boss; 109. Second boss; 110. Rotary drum; 111. First slider; 112. Second slider; 113. First spiral groove; 114. Second spiral groove; 115. Third spiral groove; 116. Guide rod; 117. Mounting bracket; 118. Connecting rod; 119. Rotary wheel; 120. Pneumatic assembly. Detailed Implementation
[0025] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below through embodiments and in conjunction with the accompanying drawings. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention.
[0026] The component designations used in this document, such as "first" and "second," are merely for distinguishing the described objects and do not have any sequential or technical meaning. The terms "connection" and "linkage" used in this invention, unless otherwise specified, include both direct and indirect connections (linkages). It should be understood that the terms "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," "clockwise," and "counterclockwise," indicating orientations or positional relationships, are based on the orientations or positional relationships shown in the accompanying drawings and are used only for the convenience of describing the invention and simplifying the description. They 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 limiting the invention.
[0027] 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.
[0028] As shown in Figures 1 to 6, this embodiment of the invention provides a low-emission, high-precision bellows regulating valve, comprising: a valve body 100, a plug 101, a valve stem 102, and a sealing mechanism. The valve body 100 is provided with an inlet 103 and an outlet 104, which are connected within the valve body 100 through a through hole. The plug 101 is slidably disposed within the valve body 100 and is used to block the through hole. One end of the valve stem 102 is connected to the plug 101, and the other end of the valve stem 102 passes through the valve body 100 and is located outside the valve body 100. The valve stem 102 is slidably connected to the valve body 100. The sealing mechanism includes an Ω-shaped bellows 105, a U-shaped bellows 106, a connector 107, and an adjusting assembly. Both the Ω-shaped bellows 105 and the U-shaped bellows 106 are sleeved on the valve stem 102 and located inside the valve body 100. The connector 107 is disposed on the valve stem 102 and is used to connect the Ω-shaped bellows 105 and the U-shaped bellows 106. The Ω-shaped bellows 105, the U-shaped bellows 106, and the connector 107 together isolate the valve stem 102 portion located inside the valve body 100 from the medium inside the valve body 100. When the valve stem 102 slides on the valve body 100, the adjusting assembly controls the relative position of the connecting piece 107 on the valve stem 102, so that when the through hole is opened, the shrinkage of each corrugation of the Ω-shaped bellows 105 is greater than the shrinkage of each corrugation of the U-shaped bellows 106; when the through hole is closed, the elongation of each corrugation of the Ω-shaped bellows 105 is less than the elongation of each corrugation of the U-shaped bellows 106.
[0029] The Ω-shaped bellows 105 has a bellows shape resembling the letter Ω, with a shallower bellows depth. This shallower bellows shape results in a relatively larger contact area between the bellows during compression, allowing for more even pressure distribution. This reduces localized stress concentration, lowers the risk of fatigue cracks due to stress concentration, and improves durability under compression conditions. The U-shaped bellows 106 has a deeper bellows shape and a larger radius of curvature. During tension, the openings of the bellows better disperse stress, preventing excessive stress concentration at the bellows root, thus reducing the risk of fatigue cracks. Risks may arise; through the coordinated arrangement of connector 107 and adjustment component, when both Ω-shaped corrugated pipe 105 and U-shaped corrugated pipe 106 contract, the contraction amount of Ω-shaped corrugated pipe 105 can be increased and the contraction amount of U-shaped corrugated pipe 106 can be decreased, thereby reducing the stress of U-shaped corrugated pipe 106 and extending its service life; at the same time, when both Ω-shaped corrugated pipe 105 and U-shaped corrugated pipe 106 elongate, the elongation of Ω-shaped corrugated pipe 105 can be decreased and the elongation of U-shaped corrugated pipe 106 can be increased, thereby reducing the stress of Ω-shaped corrugated pipe 105 and extending its service life.
[0030] In this embodiment, the valve stem 102 and the sealing mechanism located in the valve body 100 are both located in the outlet 104. When the through hole is closed, the medium pressure in the outlet 104 is less than the medium pressure in the inlet 103. The Ω-shaped bellows 105 and the U-shaped bellows 106 are subjected to less pressure, which can further extend their service life.
[0031] In this embodiment, the connector 107 is cylindrical, with a first boss 108 extending outward in its radial direction at one end and a second boss 109 extending inward in its radial direction at the other end. The connector 107 is coaxial with the valve stem 102. An Ω-shaped bellows 105 is sleeved on the connector 107, with one end connected to the first boss 108 and the other end connected to the valve body 100. A U-shaped bellows 106 is located between the connector 107 and the valve stem 102, with one end connected to the plug 101 and the other end connected to the second boss 109. The diameter of the Ω-shaped bellows 105 is larger than that of the U-shaped bellows 106. The Ω-shaped bellows 105 and the U-shaped bellows 106 have overlapping portions in the axial direction of the valve stem 102. The longer the connector 107 is in the axial direction, the greater the distance between the first boss 108 and the second boss 109 in the axial direction of the valve stem 102. The more overlapping portions the Ω-shaped bellows 105 and the U-shaped bellows 106 have, the smaller the expansion and contraction of each bellows on the Ω-shaped bellows 105 and the U-shaped bellows 106, and the smaller the stress on each bellows, thus extending the service life of the Ω-shaped bellows 105 and the U-shaped bellows 106.
[0032] In this embodiment, the first boss 108 is closer to the block 101 than the second boss 109. When the low-emission high-precision bellows regulating valve is in use, the valve stem 102 is inclined relative to the horizontal plane and is located above the block 101. When the through hole is closed, the medium pressure in the outlet 104 decreases and is gradually discharged. Since the opening direction of the connector 107 is always downward, the medium stored inside will be discharged under the influence of its own gravity, reducing the residue of the medium.
[0033] In this embodiment, the adjustment assembly includes a rotating cylinder 110, a first slider 111, and a second slider 112. The rotating cylinder 110 is sleeved on the valve stem 102 located inside the valve body 100 and is rotatably connected to the valve stem 102. The rotating cylinder 110 is provided with a first spiral groove 113, a second spiral groove 114, and a third spiral groove 115 arranged in the same direction along the axial direction of the valve stem 102 and with decreasing pitches. The second spiral groove 114 and the third spiral groove 115 are connected end to end. The first slider 111 is fixedly disposed on the valve body 100 and slides in the first spiral groove 113. The pitch of the second spiral groove 114 is greater than half the pitch of the first spiral groove 113, and the pitch of the third spiral groove 115 is less than half the pitch of the first spiral groove 113. The second slider 112 slides within the second spiral groove 114 or the third spiral groove 115 and is connected to the connector 107. When the rotating drum 110 slides along its own axial direction with the valve stem 102, it rotates around its own axis through the cooperation of the first spiral groove 113 and the first slider 111. Through the cooperation of the second slider 112 with the second spiral groove 114 and the third spiral groove 115, the connector 107 moves with the rotating drum 110 while sliding relative to the rotating drum 110. This allows adjustment of the expansion and contraction of the Ω-shaped bellows 105 and the U-shaped bellows 106, so that the elongation of the Ω-shaped bellows 105 is less than the elongation of the U-shaped bellows 106, and the contraction of the Ω-shaped bellows 105 is greater than the contraction of the U-shaped bellows 106. The Ω-shaped bellows 105 and the U-shaped bellows 106 ensure normal expansion and contraction while minimizing the stress on each other, thus extending their service life.
[0034] In this embodiment, the second boss 109 is sleeved on the rotating cylinder 110 and slidably connected to the rotating cylinder 110. The inner diameter of the U-shaped corrugated pipe 106 is slightly larger than the outer diameter of the rotating cylinder 110. The U-shaped corrugated pipe 106 and the rotating cylinder 110 are slidably connected. The connector 107 will not move in the radial direction of the rotating cylinder 110. The Ω-shaped corrugated pipe 105 and the U-shaped corrugated pipe 106 are not easy to bend during the expansion and contraction process. The corrugations on the Ω-shaped corrugated pipe 105 and the U-shaped corrugated pipe 106 are subjected to more uniform stress.
[0035] In this embodiment, when the through hole is half open, the Ω-shaped bellows 105 and the U-shaped bellows 106 are at their natural lengths, and the second slider 112 is located at the junction of the second spiral groove 114 and the third spiral groove 115. At this time, the Ω-shaped bellows 105 and the U-shaped bellows 106 are not subjected to shrinkage stress or tensile stress. When the through hole is fully open or fully closed, the Ω-shaped bellows 105 and the U-shaped bellows 106 are only subjected to half the shrinkage or elongation of the maximum distance that the block 101 moves, which reduces the stress on the Ω-shaped bellows 105 and the U-shaped bellows 106 and effectively extends their service life.
[0036] In this embodiment, flanges are provided at the ends of both the Ω-shaped bellows 105 and the U-shaped bellows 106. The Ω-shaped bellows 105 is connected to the valve body 100 and the first boss 108 respectively through the flanges, and the U-shaped bellows 106 is connected to the plug 101 and the second boss 109 respectively through the flanges. With flanges, the sealing performance of the ends of the Ω-shaped bellows 105 and the U-shaped bellows 106 is better, and the low-emission high-precision bellows regulating valve is less prone to leakage during use.
[0037] In this embodiment, the connector 107 is provided with a plurality of guide rods 116, which are arranged around the circumference of the connector 107. The end of each guide rod 116 away from the connector 107 is slidably connected to the valve body 100. When the rotating drum 110 rotates relative to the connector 107, it will apply a torsional force to the connector 107. The guide rods 116 can counteract the torsional force of the connector 107, so that the Ω-shaped bellows 105 and the U-shaped bellows 106 will not twist, thereby extending the service life of the Ω-shaped bellows 105 and the U-shaped bellows 106.
[0038] In this embodiment, the low-emission, high-precision bellows regulating valve also includes a drive mechanism. The drive mechanism is used to drive the valve stem 102 to slide along its axial direction. The drive mechanism includes a mounting bracket 117, a connecting rod 118, a rotating wheel 119, and a pneumatic assembly 120. The mounting bracket 117 is disposed on the valve body 100, and the connecting rod 118 is disposed on the mounting bracket 117 and threadedly connected to the mounting bracket 117. One end of the connecting rod 118 is rotatably connected to the valve stem 102, and the other end of the connecting rod 118 is connected to the rotating wheel 119. Rotating the rotating wheel 119 causes the connecting rod 118 to slide along its own axial direction on the mounting bracket 117, while simultaneously driving the valve stem 102 to move synchronously. The pneumatic assembly 120 can drive the connecting rod 118 to rotate through gas, thereby achieving automation.
[0039] The working principle of the low-emission, high-precision bellows control valve provided in the above embodiments is as follows:
[0040] First, install the valve body 100 in the appropriate position and allow the medium to flow from the inlet 103 to the outlet 104. To ensure communication between the inlet 103 and outlet 104, rotate the rotating wheel 119, which in turn drives the connecting rod 118 to rotate. The connecting rod 118 rotates along its own axis away from the valve body 100 via a threaded connection to the mounting bracket 117. As the connecting rod 118 rotates relative to the valve stem 102, it simultaneously slides on the mounting bracket 117, causing the valve stem 102 to move synchronously. The movement of the valve stem 102 causes the plug 101 to slide within the through hole and gradually move away from it, opening the through hole and connecting the inlet 103 and outlet 104. The medium in the inlet 103 then enters the outlet 104 through the through hole.
[0041] When the through-hole is fully closed, both the Ω-shaped bellows 105 and the U-shaped bellows 106 are in a stretched state, and the second slider 112 is located in the second spiral groove 114. As the through-hole gradually opens halfway, the portion of the valve stem 102 inside the valve body 100 gradually decreases, and the lengths of the Ω-shaped bellows 105 and the U-shaped bellows 106 between the plug 101 and the valve body 100 also gradually decrease. Simultaneously, the rotating drum 110 begins to rotate through the cooperation of the first slider 111 and the first spiral groove 113. The rotation of the rotating drum 110 causes the second slider 112 to slide in the second spiral groove 114, and the second slider 112 gradually approaches the third spiral groove 115, while the stretched Ω-shaped bellows 105 and U-shaped bellows 106 gradually return to their original positions. When the through-hole is opened halfway, the second slider 112 slides on the rotating drum 110 to the junction of the second spiral groove 114 and the third spiral groove 115. At this time, the rotating wheel 119 continues to rotate, the length of the valve stem 102 inside the valve body 100 continues to decrease, the rotating drum 110 also continues to rotate, the second slider 112 slides into the third spiral groove 115, the second slider 112 moves away from the first spiral groove 113 in the third spiral groove 115, at this time the moving speed of the second slider 112 in the axial direction of the rotating drum 110 is less than the moving speed of the rotating drum 110 in its own axial direction, the moving trend of the connecting piece 107 on the rotating drum 110 is away from the block 101, that is, the shrinkage of the Ω-shaped bellows 105 is greater than the shrinkage of the U-shaped bellows 106, so that the Ω-shaped bellows 105 shrinks more than the U-shaped bellows 106, so that the Ω-shaped bellows 105 plays a greater role and can reduce the stress on the bellows in the U-shaped bellows 106.
[0042] When the through hole is fully open and needs to be closed, the rotating wheel 119 is rotated in the opposite direction, causing the block 101 to gradually approach the through hole. The Ω-shaped bellows 105 and the U-shaped bellows 106 gradually return from their stretched state to their natural state. At this time, the second slider 112 will gradually slide to the junction of the second spiral groove 114 and the third spiral groove 115. Then, the second slider 112 will slide into the second spiral groove 114, and the Ω-shaped bellows 105 and the U-shaped bellows 106 will begin to elongate. With the cooperation of the second slider 112 and the second spiral groove 114, the connector 107 gradually moves away from the block 101. The elongation of the U-shaped bellows 106 is greater than that of the Ω-shaped bellows 105, so that the U-shaped bellows 106 plays a greater role and reduces the stress on the corrugations in the Ω-shaped bellows 105.
[0043] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.
[0044] The embodiments described above are merely illustrative of several implementations of the present invention, and while the descriptions are specific and detailed, they should not be construed as limiting the scope of the invention. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention, and these modifications and improvements all fall within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the appended claims.
Claims
1. A low-emission, high-precision bellows regulating valve, characterized in that, include: The valve body comprises a valve body, a plug, a valve stem, and a sealing mechanism. The valve body has an inlet and an outlet, which are connected within the valve body via a through-hole. The plug is slidably disposed within the valve body and seals the through-hole. One end of the valve stem is connected to the plug, and the other end passes through the valve body and is located outside the valve body, with the valve stem slidably connected to the valve body. The sealing mechanism includes an Ω-shaped bellows, a U-shaped bellows, a connector, and an adjusting assembly. Both the Ω-shaped and U-shaped bellows are fitted onto the valve stem and located inside the valve body. The connector is... Located on the valve stem and used to connect Ω-shaped and U-shaped bellows, the Ω-shaped and U-shaped bellows, together with the connector, isolate the valve stem portion located inside the valve body from the medium inside the valve body. When the valve stem slides on the valve body, the adjusting component controls the relative position of the connector on the valve stem, so that when the through hole is open, the contraction of each bellows of the Ω-shaped bellows is greater than that of each bellows of the U-shaped bellows; when the through hole is closed, the elongation of each bellows of the Ω-shaped bellows is greater than that of each bellows of the U-shaped bellows.
2. The low-emission, high-precision bellows regulating valve according to claim 1, characterized in that, The valve stem and sealing mechanism, both located within the valve body, are situated in the liquid outlet.
3. The low-emission, high-precision bellows regulating valve according to claim 1, characterized in that, The connector is cylindrical, with a first boss extending outward in its radial direction at one end and a second boss extending inward in its radial direction at the other end. The connector is coaxial with the valve stem. An Ω-shaped bellows is sleeved on the outside of the connector, with one end connected to the first boss and the other end connected to the valve body. A U-shaped bellows is located between the connector and the valve stem, with one end connected to the plug and the other end connected to the second boss.
4. The low-emission, high-precision bellows regulating valve according to claim 3, characterized in that, The first protrusion is closer to the block than the second protrusion.
5. A low-emission, high-precision bellows regulating valve according to claim 3, characterized in that, The adjusting assembly includes a rotating cylinder, a first slider, and a second slider. The rotating cylinder is sleeved on the valve stem located inside the valve body and is rotatably connected to the valve stem. The rotating cylinder has a first spiral groove, a second spiral groove, and a third spiral groove arranged sequentially along the axial direction of the valve stem with the same direction of rotation and decreasing pitch. The second spiral groove and the third spiral groove are connected end to end. The first slider is fixedly mounted on the valve body and slides in the first spiral groove. The pitch of the second spiral groove is greater than half the pitch of the first spiral groove, and the pitch of the third spiral groove is less than half the pitch of the first spiral groove. The second slider slides in the second spiral groove or the third spiral groove and is connected to the connecting piece.
6. A low-emission, high-precision bellows regulating valve according to claim 5, characterized in that, The second boss is sleeved on the rotating drum and slidably connected to the rotating drum, and the U-shaped bellows is slidably connected to the rotating drum.
7. A low-emission, high-precision bellows regulating valve according to claim 5, characterized in that, When the through hole is opened halfway, the Ω-shaped bellows and the U-shaped bellows are at their natural lengths, while the second slider is located at the junction of the second and third spiral grooves.
8. A low-emission, high-precision bellows regulating valve according to claim 3, characterized in that, Both the Ω-shaped bellows and the U-shaped bellows are equipped with flanges at their ends. The Ω-shaped bellows are connected to the valve body and the first boss respectively through the flanges, and the U-shaped bellows are connected to the plug and the second boss respectively through the flanges.
9. A low-emission, high-precision bellows regulating valve according to claim 3, characterized in that, The connector is provided with multiple guide rods, which are arranged around the circumference of the connector, and the end of each guide rod away from the connector is slidably connected to the valve body.
10. A low-emission, high-precision bellows regulating valve according to claim 1, characterized in that, It also includes a drive mechanism for driving the valve stem to slide along its axial direction.