Automatic vacuum sampling valve

Abstract

The utility model discloses an automatic vacuum sampling valve which comprises a main valve body, a stroke sleeve and a valve rod. One end of the stroke sleeve is fixedly connected to the second end of the main valve body, and the other end is closed; air inlet holes communicated with the inner cavity of the stroke sleeve are respectively formed in the outer wall of the stroke sleeve close to two ends; the valve rod is arranged in an inner cavity of the stroke sleeve, the head end of the valve rod faces the main valve body, and a gap is formed between the valve rod and the inner wall face of the stroke sleeve. A first air seal is arranged in an inner cavity of the stroke sleeve close to the main valve body; a second air seal and a third air seal are arranged on the surface, close to the tail end, of the valve rod; a first sealing cavity is defined by the valve rod, the inner wall of the stroke sleeve, the first air seal and the second air seal, and a second sealing cavity is defined by the third air seal and an inner cavity of the stroke sleeve. According to the automatic vacuum sampling valve disclosed by the utility model, sampling can be realized by controlling the movement of the valve rod in a pneumatic manner, and automatic sampling can also be realized by matching with a control program; in addition, the sampling valve can also be used as a blanking valve for blanking.

Description

Technical Field

[0001] This utility model relates to the field of sampling device technology, specifically to an automatic vacuum sampling valve. Background Technology

[0002] Sampling valves are devices used to obtain samples of media from pipelines or equipment and perform compositional analysis. In many situations requiring frequent chemical analysis of media samples, specialized sampling valves are often used and are now widely applied in the food, chemical, and pharmaceutical industries. During the operation of large chemical equipment, sampling valves are required for real-time sampling, which is then sent to a testing center for analysis.

[0003] Currently, existing sampling valves are generally manual sampling valves, which are moved within the valve chamber by pushing a push rod or turning a handwheel to achieve sampling. However, manual sampling not only consumes a lot of manpower, but the pushing or turning process is also difficult to control the force, making it hard to ensure the accuracy of movement, resulting in many inconveniences of the manual function of this sampling valve. Utility Model Content

[0004] The technical problem to be solved by this utility model is to provide an automatic vacuum sampling valve, which can achieve sampling by pneumatically controlling the movement of the valve stem; compared with manual operation, the control of the valve stem is more precise, saving time and effort; in addition, the sampling valve can achieve automatic sampling when used with a control program.

[0005] To solve the above-mentioned technical problems, this utility model provides the following technical solution:

[0006] This utility model provides an automatic vacuum sampling valve, comprising:

[0007] The main valve body has a first end and a second end that are arranged opposite to each other; the first end is used to connect to the main equipment, and the second end is provided with a sampling tube that communicates with the valve cavity of the main valve body; a branch tube is connected to the sampling tube, and the outlet end of the sampling tube is used to connect to a sampling bottle.

[0008] A travel sleeve, one end of which is fixedly connected to the second end of the main valve body, and the other end is closed; the outer wall of the travel sleeve has an air inlet near each end, communicating with its inner cavity, and the air inlet is used to connect to an external pneumatic device; and

[0009] A valve stem is arranged in the inner cavity of the stroke sleeve, and a first end of the valve stem faces the main valve body, and a gap is formed between the valve stem and the inner wall of the stroke sleeve for gas flow; a first gas seal is arranged on the inner wall of the stroke sleeve close to the main valve body, and a second gas seal and a third gas seal are arranged on the surface of the valve stem close to the second end; a first sealing cavity is formed between the valve stem, the inner wall of the stroke sleeve, the first gas seal and the second gas seal, and a second sealing cavity is formed between the third gas seal and the inner cavity of the stroke sleeve;

[0010] When sampling, the first sealing cavity or the second sealing cavity is supplied with gas through the pneumatic device and the gas inlet hole, and the gas flow drives the valve stem to move in the inner cavity of the stroke sleeve to achieve sampling.

[0011] Further, an installation flange is arranged on the outer wall of the main valve body, and the installation flange is located between the first end and the second end, and is used for installing the first end on the host device.

[0012] Further, a first air soft plug is arranged on the valve stem, and the first air soft plug is located between the first gas seal and the second gas seal; the outer circumferential surface of the first air soft plug abuts against the inner wall of the stroke sleeve, and a plurality of air inlets are formed in the circumferential surface of the first air soft plug.

[0013] Further, the surface of the first air soft plug towards the first gas seal outwardly protrudes to form a limiting ring sleeve which is sleeved on the valve stem, and a gap is formed between the surface of the limiting ring sleeve and the inner wall of the stroke sleeve for gas flow;

[0014] When the limiting ring sleeve abuts against the first gas seal, the gas inlet on the side of the stroke sleeve close to the main valve body is opposite to the limiting ring sleeve.

[0015] Further, a second air soft plug is arranged on the valve stem, and the second air soft plug is located between the third gas seal and the second end of the valve stem; the outer circumferential surface of the second air soft plug abuts against the inner wall of the stroke sleeve, and a plurality of air inlets are formed in the circumferential surface of the second air soft plug.

[0016] Further, the surface of the valve stem is provided with a ring groove, and the second gas seal and the third gas seal are sleeved in the ring groove.

[0017] Further, the surface of the valve stem outwardly protrudes to form three convex rings, and the ring groove is formed between adjacent two convex rings; the first air soft plug and the second air soft plug abut against the convex rings.

[0018] Further, a buffer sleeve is arranged on the second end of the valve stem.

[0019] Further, the first venting soft plug, the second venting soft plug and the buffer sleeve are all made of polytetrafluoroethylene.

[0020] Further, a boss is formed in the valve cavity of the main valve body near the stroke sleeve, and an oil seal is installed at the boss; one end of the first gas seal abuts against the oil seal, and the other end is limited by the boss in the inner cavity of the stroke sleeve.

[0021] Compared with the prior art, the automatic vacuum sampling valve has the advantages that:

[0022] 1. The automatic vacuum sampling valve can control the movement of the valve rod in a pneumatic manner, so as to realize sampling or discharging; compared with manual operation, the control of the valve rod is more accurate, time-saving and labor-saving; in addition, when the sampling valve is used in cooperation with a control program, automatic sampling can be realized.

[0023] 2. The automatic vacuum sampling valve has a simple structure, and all components are detachable and convenient to clean, so that the maintenance cost is reduced, and the maintenance work in the later period is facilitated.

[0024] 3. The automatic vacuum sampling valve can introduce nitrogen into the pipeline through the branch pipe to temporarily destroy the vacuum when sampling, so that the sample in the equipment flows out, has wide applicability, and can be applied to sampling of liquid, powder, particles and crystalline substances, and can meet the technical requirements.

[0025] 4. The automatic vacuum sampling valve is not only suitable for sampling, but also can be used as a discharging valve to discharge. BRIEF DESCRIPTION OF DRAWINGS

[0026] Figure 1 is a cross-sectional view of the automatic vacuum sampling valve of an embodiment of the utility model;

[0027] Figure 2 is a side view of the first venting soft plug;

[0028] Figure 3 is a cross-sectional view of the first venting soft plug;

[0029] 100, main valve body; 110, first end; 120, second end; 130, mounting flange; 140, oil seal;

[0030] 200, sampling pipe; 210, branch pipe; 220, sampling pipe joint; 230, sampling bottle; 240, limiting cylinder; 250, quick release valve;

[0031] 300, stroke sleeve; 310, first gas inlet hole; 320, second gas inlet hole; 330, first gas seal;

[0032] 400, valve stem; 410, first air-soft plug; 411, air vent; 420, limiting ring; 430, convex ring; 440, second air seal; 450, third air seal; 460, second air-soft plug; 470, buffer sleeve. DETAILED DESCRIPTION

[0033] The technical solutions in the embodiments of the present application will be clearly and completely described with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor fall within the scope of protection of the present application.

[0034] In the drawings, components with the same structure are denoted by the same reference numerals, and components with similar structures or functions are denoted by similar reference numerals. The directions mentioned in the present application, such as up, down, front, back, left, right, inside, outside, upper surface, lower surface, side surface, top surface, bottom, front end, rear end, terminal end, etc., are only directions in the drawings, and are used to explain and describe the present application, but are not used to limit the protection scope of the present application.

[0035] In the drawings, components with the same structure are denoted by the same reference numerals. When a component is described as "on" another component, the component can be directly placed on the other component; or there can be an intermediate component, and the component is placed on the intermediate component, and the intermediate component is placed on the other component. When a component is described as "mounted to" or "connected to" another component, it can be understood as being directly "mounted" or "connected", or the component is indirectly "mounted to" or "connected to" the other component through an intermediate component.

[0036] As Figure 1 shown, an embodiment of the present application provides an automatic vacuum sampling valve. The vacuum sampling valve can control the movement of the valve stem 400 in a pneumatic manner to realize sampling or discharging, which is time-saving and labor-saving compared with manual operation. The automatic vacuum sampling valve can be used in various chemical equipment and drying equipment, and can be used for sampling various substances such as liquid, powder and crystalline substances.

[0037] Specifically, the automatic vacuum sampling valve specifically includes a main valve body 100, a stroke sleeve 300 and a valve stem 400.

[0038] Please refer to Figure 1The main valve body 100 is a pipe with a valve cavity inside. The main valve body 100 has a first end 110 and a second end 120 arranged oppositely, wherein the first end 110 is used to connect to a main equipment (such as a chemical equipment, a drying equipment, etc.). Preferably, an installation flange 130 is arranged on the outer wall of the main valve body 100, which is located between the first end 110 and the second end 120, so that the first end 110 of the main valve body 100 can be installed to the main equipment through the installation flange 130.

[0039] Please refer to Figure 1 A sampling pipe 200 is arranged on the second end 120 of the main valve body 100 and communicates with the valve cavity of the main valve body 100. The sampling pipe 200 can be integrally formed with the main valve body 100 or welded to the main valve body 100. The sampling pipe 200 is preferably arranged obliquely on the second end 120 of the main valve body 100 and extends away from the first end 110, so as to facilitate the outflow of the sample. A branch pipe 210 is further arranged on the sampling pipe 200 and is used to introduce nitrogen into the main valve body 100 to temporarily destroy the vacuum environment, so as to make the sample in the equipment flow out. Preferably, a nitrogen valve is arranged on the branch pipe 210, and the introduction of nitrogen can be controlled by opening and closing the nitrogen valve.

[0040] An outlet end of the sampling pipe 200 is connected with a sampling bottle 230 for receiving the sample flowing out of the sampling pipe 200. In some embodiments, the sampling bottle 230 is connected to the outlet end of the sampling pipe 200 through a sampling pipe joint 220. Specifically, please refer to Figure 2 One end of the sampling pipe joint 220 is inserted into the outlet end of the sampling pipe 200 and locked to the sampling pipe 200 through a quick release valve 250. The bottle opening of the sampling bottle 230 is sealingly inserted into the other end of the sampling pipe joint 220. The other end of the sampling pipe joint 220 is provided with external threads, and the sampling bottle 230 is provided with a limiting cylinder 240 with internal threads, which is screwed to the sampling pipe joint 220, so as to fix the sampling bottle 230 to the sampling pipe joint 220. Preferably, further, a plurality of observation holes are formed in the outer circumferential surface of the limiting cylinder 240, so that the observation holes can be used to observe whether the sample enters the sampling bottle 230 at any time.

[0041] The valve cavity of the main valve body 100 is provided with a seal at the position on both sides of the sampling pipe. For example, a seal groove can be formed in the inner wall surface of the main valve body 100 at the corresponding position, and a sealing ring is embedded in the seal groove. In this embodiment, a seal groove is formed at the first end of the valve rod 400, and a sealing ring is embedded therein. In addition, a boss is arranged near the travel sleeve 300 in the valve cavity of the main valve body 100, and an oil seal 140 is arranged on the boss, and the other end of the oil seal 140 is limited by the end surface of the travel sleeve 300. In this way, the sealing effect can also be achieved by the sealing ring on the valve rod 400 and the oil seal 140 in the main valve body 100.

[0042] Please refer to Figure 1 The stroke sleeve 300 is also a pipe-shaped component, and one end face of the stroke sleeve 300 is provided with a mounting flange 130; the end face of the second end 120 of the main valve body 100 is also provided with a mounting flange 130, so that the stroke sleeve 300 is fixedly connected to the second end 120 of the main valve body 100 through the pair of flanges.

[0043] The other end of the stroke sleeve 300 is closed, that is, the end of the stroke sleeve 300 is sealed. In some embodiments, an end cover can be sealingly mounted on the end of the stroke sleeve 300, or the end cover can be welded to the end of the stroke sleeve 300 to achieve sealing. The outer wall of the stroke sleeve 300 is provided with an air inlet hole near each end in communication with the inner cavity of the stroke sleeve 300, which is defined as a first air inlet hole 310 near the side of the main valve body 100 and a second air inlet hole 320 away from the side of the main valve body 100. The first air inlet hole 310 and the second air inlet hole 320 are used to communicate with external pneumatic devices, such as various devices with air charging functions, for example, air pumps, preferably air pumps with flow control functions, so that the air inlet amount can be accurately controlled.

[0044] The valve stem 400 is arranged in the inner cavity of the stroke sleeve 300, and the first end of the valve stem 400 faces the main valve body 100. The valve stem 400 can enter the valve cavity of the main valve body 100 and block the valve cavity. The valve stem 400 is made of metal material, preferably 304 stainless steel. The outer diameter of the valve stem 400 is smaller than the diameter of the inner cavity of the stroke sleeve 300, that is, there is a gap between the valve stem 400 and the inner wall of the stroke sleeve 300; in this way, during use of the sampling valve, it is ensured that the valve stem 400 does not rub against the inner wall of the stroke sleeve 300, the wear of the surface of the valve stem 400 is reduced, and the service life of the valve stem 400 is prolonged. In addition, the gap between the valve stem 400 and the inner wall of the stroke sleeve 300 can ensure the flow of gas, thereby achieving the movement of the valve stem 400.

[0045] The inner cavity of the stroke sleeve 300 is provided with a first air seal 320 fixed to the inner wall of the stroke sleeve 300 near the main valve body 100, one end of the first air seal 320 abuts against the oil seal 140, and the other end is limited by the boss formed in the inner cavity of the stroke sleeve 300. The surface of the tail end of the valve stem 400 is fixedly provided with a second air seal 440 and a third air seal 450. Among them, the valve stem 400, the inner wall of the stroke sleeve 300, the first air seal 320 and the second air seal 440 surround to form a first sealing cavity, and the third air seal 450 and the inner cavity of the stroke sleeve 300 surround to form a second sealing cavity. The first air inlet hole 310 is opposite to the first sealing cavity, and the second air inlet hole 320 is opposite to the second sealing cavity.

[0046] When sampling, the first sealed cavity is supplied with air through the external pneumatic device and the first air inlet hole 310. Since the first air seal 320 is fixed to the inner wall surface of the stroke sleeve 300 and the second air seal 440 is fixed to the valve rod 400, as the amount of air supply increases, the air flow will push the second air seal 440, thereby driving the valve rod 400 to move away from the main valve body 100, so that the leading end of the valve rod 400 is withdrawn from the valve cavity of the main valve body 100, until the tube opening of the sampling tube 200 is exposed in the valve cavity of the main valve body 100; then, the sample can enter the sampling bottle 230 through the sampling tube 200, and the sampling is completed.

[0047] Then, the second sealed cavity is supplied with air through the external pneumatic device and the second air inlet hole 320. Since the other end of the stroke sleeve 300 is closed and the third air seal 450 is fixed to the valve rod 400. Therefore, as the amount of air supply increases, the air flow will push the third air seal 450, thereby driving the valve rod 400 to move towards the main valve body 100, so that the leading end of the valve rod 400 enters the valve cavity of the main valve body 100, until the tube opening of the sampling tube is blocked.

[0048] In some embodiments of the present application, the valve rod 400 is further sleeved with a first air-vent soft plug 410, and the first air-vent soft plug 410 is located between the first air seal 320 and the second air seal 440. As shown in Figures 2-3 The first air-vent soft plug 410 is a circular ring component, and its outer peripheral surface abuts against the inner wall surface of the stroke sleeve 300. Therefore, the first air-vent soft plug 410 can play a guiding role, so that the valve rod 400 can move along the axis of the inner cavity of the stroke sleeve 300. The first air-vent soft plug 410 is made of soft material, and is preferably made of polytetrafluoroethylene material. During the movement of the valve rod 400, the first air-vent soft plug 410 made of soft material is beneficial to reducing the abrasion between the inner wall surface of the stroke sleeve 300. A plurality of air-vent holes 411 are formed on the circumference of the first air-vent soft plug 410, which provides a flow channel for the air flow, so that the air flow can flow to the second air seal 440 and drive the valve rod 400 to move. Preferably, the number of air-vent holes 411 is four, which are uniformly distributed on the circumference of the first air-vent soft plug 410.

[0049] As shown in Figures 2-3 In some embodiments of the present application, the surface of the first air-vent soft plug 410 towards the first air seal 320 protrudes outward to form a limiting ring sleeve 420 which is sleeved on the valve rod 400. The outer diameter of the limiting ring sleeve 420 is smaller than that of the first air-vent soft plug 410, so that there is a gap between the surface of the limiting ring sleeve 420 and the inner wall surface of the stroke sleeve 300 for the air flow to pass through; and it can be understood that the limiting ring sleeve 420 should not block the air-vent holes 411. Preferably, the limiting ring sleeve 420 is integrally formed with the first air-vent soft plug 410.

[0050] The limiting ring sleeve 420 moves together with the valve rod 400, and when the limiting ring sleeve 420 abuts against the first gas seal 320, the valve rod 400 moves to its limit position, that is, the valve rod 400 enters the valve cavity of the main valve body 100 and blocks the pipe opening of the sampling pipe. It can be understood that the limiting ring sleeve 420 limits the movement of the valve rod 400 at this time. Moreover, it is necessary to ensure that the limiting ring sleeve 420 has sufficient length (that is, the length in the axial direction of the valve rod 400) so that the first gas inlet on the stroke sleeve 300 is opposite to the limiting ring sleeve 420 when the limiting ring sleeve 420 abuts against the first gas seal 320.

[0051] In some embodiments of the utility model, the second air soft plug 460 is further sleeved on the valve rod 400, and the second air soft plug 460 is located between the third gas seal 450 and the tail end of the valve rod 400. The second air soft plug 460 is similar in shape to the first air soft plug 410 and is also a circular ring component, and the outer circumferential surface thereof abuts against the inner wall surface of the stroke sleeve 300. Similarly, the second air soft plug 460 can play a guiding role, and in cooperation with the first air soft plug 410, the valve rod 400 can move better along the axis of the inner cavity of the stroke sleeve 300, and deviation can be avoided. The second air soft plug 460 is made of soft material, and is preferably made of polytetrafluoroethylene material. During the movement of the valve rod 400, the second air soft plug 460 made of soft material is beneficial to reducing the wear between the inner wall surface of the stroke sleeve 300. A plurality of air inlets 411 are formed in the circumferential ring of the second air soft plug 460, which provides a flow channel for the gas flow, so that the gas flow can flow to the third gas seal 450 and push the valve rod 400 to move. Preferably, the number of air inlets 411 is four, which are uniformly distributed on the circumferential ring of the second air soft plug 460.

[0052] In the utility model, the surface of the valve rod 400 is provided with a ring groove, and the second gas seal 440 and the third gas seal 450 are sleeved in the ring groove, so as to be fixedly installed on the valve rod 400. Figure 1 As shown in the preferred embodiment, the outer circumferential surface of the valve rod 400 outwardly protrudes to form three convex rings 430 arranged in sequence, and the ring groove is formed between the adjacent two convex rings 430 for installing the second gas seal 440 and the third gas seal 450. In order to avoid that the convex ring 430 blocks the air inlets 411 on the first air soft plug 410 and the second air soft plug 460, the convex ring 430 preferably comprises a plurality of protruding portions and is distributed in the circumferential direction. At this time, one end of the first air soft plug 410 and the second air soft plug 460 respectively abuts against the convex ring 430, so as to realize the limiting of the valve rod 400. In addition, the other end of the third gas seal 450 can be limited by the shaft ring.

[0053] In some embodiments of the utility model, the tail end of valve rod 400 is also sleeved with buffer sleeve 470, buffer sleeve 470 is circular ring part, and the gap for airflow passing between the outer circumferential surface of buffer sleeve 470 and the inner wall surface of stroke sleeve 300. The tail end of buffer sleeve 470 protrudes from the tail end of valve rod 400, which can play the role of buffering impact. In the process of valve rod 400 movement, buffer sleeve 470 can avoid valve rod 400 directly impacting the closed end of stroke sleeve 300, thereby being favorable for reducing vibration and prolonging the service life of valve rod 400. Buffer sleeve 470 is also prepared from soft material, preferably polytetrafluoroethylene material. Buffer sleeve 470 can be combined and limited by the boss formed on valve rod 400 and the shaft ring.

[0054] In addition, in some embodiments, the inner wall of main valve body 100, the inner wall of sampling pipe and the surface of valve rod 400 all have corrosion-resistant coating, so that the sampling valve has good corrosion resistance, can resist strong acid and strong alkali, effectively avoids the corrosion of sample on the sampling valve and prolongs the service life of the sampling valve.

[0055] In summary, the automatic vacuum sampling valve provided by the utility model can realize sampling by controlling the movement of valve rod through gas, and can also realize automatic sampling when used with control program. In addition, in addition to being used as a sampling valve, it can also be used as a blanking valve for blanking operation.

[0056] The above-mentioned embodiments are only preferred embodiments for fully illustrating the utility model, and the protection scope of the utility model is not limited thereto. The equivalent replacement or transformation of the technical personnel in the technical field on the basis of the utility model is within the protection scope of the utility model. The protection scope of the utility model is subject to the claims.

Claims

1. An automatic vacuum sampling valve characterized by, The utility model provides a valve for sampling, comprising: a main valve body having a first end and a second end arranged oppositely, the first end being used for connecting a host device, the second end being provided with a sampling tube communicating with a valve cavity of the main valve body, the sampling tube being connected with a branch tube, and an outlet end of the sampling tube being used for connecting a sampling bottle; a stroke sleeve being fixedly connected to the second end of the main valve body at one end and being closed at the other end, the outer wall of the stroke sleeve being provided with an air inlet hole communicating with the inner cavity of the stroke sleeve at each end, the air inlet hole being used for communicating with an external pneumatic device; and a valve rod being arranged in the inner cavity of the stroke sleeve, the first end of the valve rod facing the main valve body, and the valve rod and the inner wall of the stroke sleeve having a gap for air flow, the inner cavity of the stroke sleeve being provided with a first air seal fixed to the inner wall of the stroke sleeve near the main valve body, the surface of the valve rod near the tail end being provided with a second air seal and a third air seal, the valve rod, the inner wall of the stroke sleeve, the first air seal and the second air seal surrounding to form a first sealed cavity, and the third air seal and the inner cavity of the stroke sleeve surrounding to form a second sealed cavity; wherein, when sampling, air is introduced into the first sealed cavity or the second sealed cavity through the pneumatic device and the air inlet hole, and the air flow drives the valve rod to move in the inner cavity of the stroke sleeve to achieve sampling.

2. An automatic vacuum sampling valve according to claim 1, wherein, The outer wall of the main valve body is further provided with a mounting flange between the first end and the second end, which is used for mounting the first end to the host device.

3. An automatic vacuum sampling valve according to claim 1, wherein The valve rod is further sleeved with a first air soft plug between the first air seal and the second air seal, the outer peripheral surface of the first air soft plug abutting against the inner wall of the stroke sleeve, and a plurality of air vents are formed on the circumference of the first air soft plug.

4. An automatic vacuum sampling valve according to claim 3, wherein, The surface of the first air soft plug facing the first air seal outwardly protrudes to form a limiting ring sleeve sleeved on the valve rod, and the surface of the limiting ring sleeve and the inner wall of the stroke sleeve have a gap for air flow; When the limiting ring sleeve abuts against the first air seal, the air inlet on the side of the stroke sleeve near the main valve body is opposite to the limiting ring sleeve.

5. An automatic vacuum sampling valve according to claim 3, wherein, The valve rod is further sleeved with a second air soft plug between the third air seal and the tail end of the valve rod, the outer peripheral surface of the second air soft plug abutting against the inner wall of the stroke sleeve, and a plurality of air vents are formed on the circumference of the second air soft plug.

6. An automatic vacuum sampling valve according to claim 5, wherein, The surface of the valve rod is provided with a ring groove, and the second air seal and the third air seal are sleeved in the ring groove.

7. An automatic vacuum sampling valve according to claim 6, wherein, The surface of the valve rod outwardly protrudes to form three convex rings, and the ring groove is formed between adjacent two convex rings; the first air soft plug and the second air soft plug abut against the convex rings.

8. An automatic vacuum sampling valve according to claim 5, wherein, A buffer sleeve is sleeved on the tail end of the valve rod.

9. An automatic vacuum sampling valve according to claim 8, wherein, The first air soft plug, the second air soft plug and the buffer sleeve are all made of polytetrafluoroethylene.

10. An automatic vacuum sampling valve according to claim 1, wherein, A boss is formed in the valve cavity of the main valve body near the stroke sleeve, an oil seal is mounted on the boss, one end of the first air seal abuts against the oil seal, and the other end is limited by the boss in the inner cavity of the stroke sleeve.

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