Pneumatic diaphragm valve

Abstract

The pneumatic diaphragm valve comprises a valve body, an annular valve seat, a diaphragm and an actuator, the actuator comprises a cylinder shell, a piston rod assembly arranged in the cylinder shell and a spring elastically abutting against the piston rod assembly, and the pneumatic diaphragm valve further comprises a first installation seat arranged in the cylinder shell. The first mounting seat comprises an annular connecting part and an annular inner extending part which is axially arranged at the radial inner end of the annular connecting part in an extending manner; the piston rod assembly comprises a gas channel, a rod body and a piston fixed to the outer wall of the rod body, and the rod body slidably penetrates through the inner side of the annular inner extending part. Due to the arrangement of the annular inner extension part, a guide surface of the first mounting seat to the rod body is added, the rod body can be effectively guided and prevented from inclining, meanwhile, driving gas is easier to enter a larger initial driving surface of a driving gas groove acting piston which always exists, and the pneumatic diaphragm valve has higher response speed and longer service life.

Description

Technical Field

[0001] The utility model relates to the technical field of valve bodies, in particular to a pneumatic diaphragm valve. Background Art

[0002] The modular gas supply system (IGS) is a device used for gas control in the semiconductor industry. As semiconductor manufacturing processes become more advanced, the requirements for gas control equipment are also increasing. The modular gas supply system uses a combination of flow blocks and fluid controllers (stacked blocks) to form at least one pipeline line on the substrate, and adopts a modular design. While reducing the size of the equipment, installation and maintenance become simpler. For example, the existing fluid control device / system includes at least one pipeline line, each pipeline line includes a number of fluid controllers and flow blocks for installing them, where the fluid controller can be a pneumatic diaphragm valve, a manual pneumatic diaphragm valve, etc. Valves in the pipeline line are mainly used to control the on and off of process gases.

[0003] The pneumatic diaphragm valve of the prior art includes a valve body, a valve seat, a diaphragm, and an actuator mounted on the valve body. The actuator includes a housing, a piston rod assembly having a gas flow passage mounted within the housing, and a spring that elastically presses against the piston rod assembly, thereby maintaining the pneumatic diaphragm valve in a normally open or normally closed state. The piston rod assembly includes a rod body and a piston formed on the rod body. A pressure air chamber connected to the gas flow passage is formed on one side of the piston. Air is introduced and exhausted through the pressure air chamber and the gas flow passage to achieve axial sliding of the piston, thereby driving the piston rod assembly to abut or separate from the diaphragm, causing the diaphragm and the valve seat to abut or separate, thereby closing or opening the valve. The pneumatic diaphragm valve also includes a mounting seat disposed within the housing. The mounting seat includes an annular horizontal portion. The rod body slides through the horizontal portion. Therefore, the thickness of the horizontal portion serves to guide the rod body to prevent tilting during the axial sliding of the piston rod assembly. The space between the upper or lower surface of the horizontal portion and the upper or lower surface of the piston constitutes the pressure air chamber, and the axial sliding of the piston can be limited by abutment with the horizontal portion.

[0004] However, the above-mentioned pneumatic diaphragm valve has some defects. On the one hand, the thickness of the horizontal part in the prior art is insufficient, resulting in insufficient axial length of the guide surface, and the piston rod assembly often tilts to a certain extent, which affects the axial sliding of the piston rod assembly and causes other effects; on the other hand, the axial relative surfaces of the piston and the horizontal part are planes that are basically equivalent to the cross-sectional area of ​​the pressure air cavity. If the axial relative surfaces of the piston and the horizontal part are very close or offset, not only will the space of the pressure air cavity be compressed to a very small size, although there will still be a small gap between the two due to unevenness after offsetting each other, it will make it difficult for gas to enter the pressure air cavity / gap between the piston and the horizontal part, and the area of ​​the piston surface used for contact with the gas is greatly reduced, resulting in a reduction in the initial driving surface. This is because the surface of the piston that is offset from the horizontal part cannot contact the gas. Under the premise that the pressure of the incoming gas is constant, this will cause problems for the opening and closing of both normally open valves and normally closed valves.

[0005] For example, for a normally open pneumatic diaphragm valve, the compressed spring needs to lift the piston rod assembly to overcome the deadweight of the piston rod assembly, so that there is a gap between the bottom of the piston rod assembly and the diaphragm pressing piece, and the diaphragm pressing piece will not press down the diaphragm. If the force of the compressed spring is too small, the piston rod assembly cannot be lifted to the appropriate height for a long time, and the piston rod assembly presses down the diaphragm pressing piece, causing the normally open diaphragm valve to fail. If the force of the compressed spring is too large, the piston rod assembly will abut against the axial relative surface of the horizontal part. The abutment area between the two is large, and the pressure air cavity is compressed into a gap, making it difficult for gas to enter the pressure air cavity, and the initial driving surface is reduced, making it impossible to quickly or even directly open the diaphragm. The valve is opened and closed by the piston, and the diaphragm pressing part is pressed downward by the compressed spring and the deadweight of the piston rod assembly, and the diaphragm pressing part presses the diaphragm downward. After long-term use and multiple impacts, the bottom end of the piston rod assembly and the top end of the diaphragm pressing part are worn. The piston rod assembly moves downward under the influence of the compressed spring and the deadweight of the piston. The axial relative surfaces of the piston and the horizontal part are very close to or against each other, and the contact area between the two is large, and the pressure air cavity is compressed into a gap, which makes it difficult for gas to enter the pressure air cavity and the initial driving surface is reduced, making it impossible to respond to opening and closing quickly or even directly.

[0006] Therefore, it is necessary to design a pneumatic diaphragm valve that solves the problems of insufficient guide surface of the piston rod assembly and reduced initial driving surface of the piston. Utility Model Content

[0007] In view of the deficiencies in the prior art, the purpose of the present invention is to provide a pneumatic diaphragm valve that solves the problems of insufficient guide surface of the piston rod assembly and reduced initial driving surface of the piston in the prior art pneumatic diaphragm valve.

[0008] In order to achieve the above purpose, the present invention adopts the following technical solutions:

[0009] A pneumatic diaphragm valve, comprising:

[0010] A valve body having a first fluid passage and a second fluid passage;

[0011] an annular valve seat, disposed on the valve body and surrounding an outer peripheral side of a top end of the first fluid channel, the first fluid channel and the second fluid channel being connected via the annular valve seat;

[0012] a diaphragm, elastically deformable, sealingly disposed on the valve body and located above the annular valve seat;

[0013] an actuator for applying or removing an axial force on the diaphragm so that the diaphragm abuts against or leaves the annular valve seat, thereby closing or opening the diaphragm valve;

[0014] The actuator includes a cylinder housing connected to the top end of the valve body, a piston rod assembly disposed in the cylinder housing, and a spring elastically pressing against the piston rod assembly, wherein the piston rod assembly is axially movable and located above the diaphragm;

[0015] The actuator further includes a first mounting seat provided in the cylinder housing, the first mounting seat including an annular connecting portion and an annular inner extending portion axially extending and provided at a radial inner end of the annular connecting portion;

[0016] The piston rod assembly includes a gas channel, a rod body, and a piston fixed to the outer wall of the rod body, wherein the rod body can slidably pass through the inner side of the annular inner extension;

[0017] A driving air groove is formed between the annular connecting portion and the piston and is located radially outside the annular inner extension portion. The driving air groove is used to communicate with the gas channel. The surface of the piston facing the driving air groove is the driving surface. The driving surface is used to contact with the driving gas to drive the piston rod assembly to move axially up and down. The piston rod assembly can abut against the annular inner extension portion to limit the position.

[0018] The pneumatic diaphragm valve of the present invention has a rod body in the piston rod assembly that passes through the inner side of the axially extending annular inner extension portion. Therefore, when the piston rod assembly slides axially, it is guided by the axial thickness of the annular connection portion and the axial height of the annular inner extension portion. Compared with the prior art, the annular inner extension portion increases the guide surface height / axial length of the first mounting seat to the rod body, which can effectively guide and prevent the rod body from tilting. At the same time, since the annular inner extension portion extends axially to a predetermined height relative to the upper or lower surface of the annular connection portion, the surface area of ​​the annular inner extension portion facing the piston is smaller than the surface area of ​​the annular connection portion facing the piston, and the surface of the annular inner extension portion facing the piston and the surface of the annular connection portion facing the piston have an axial height difference, and the axial movement of the piston rod assembly can be limited by the abutment of the annular inner extension portion. After the two abut, there will always be a gap due to the unevenness of the abutment surface, and there will always be a driving gas groove with a large space in the non-abutment area between the annular connection portion and the piston. Since the gas needs to pass through the annular inner extension portion The gap between the surface of the extension facing the piston and the surface of the piston enters the driving air groove, and the surface of the annular inner extension facing the piston is smaller in area than the surface of the horizontal part (annular connecting part) facing the piston in the prior art. Even if it is limited by the surface of the piston and the abutting surface is smaller, it is easier for more gaps to exist between the abutting surfaces. The gap becomes a connecting channel between the gas channel and the driving air groove, and the radial fluid becomes shorter. The gas exchange response between the gas channel and the driving air groove is faster. Moreover, since the driving air groove always exists, the surface of the piston facing the driving air groove (the surface that the piston does not abut) will always have a large area as the initial driving surface. As long as a small amount of gas directly enters the driving air groove through the gap and acts on the initial driving surface of the piston, it has sufficient capacity to drive the piston rod assembly axially under constant gas pressure, further increasing the gap, and making the upper or lower surface of the piston basically constitute the driving surface, thereby achieving rapid response and service life of the pneumatic diaphragm valve. To sum up, on the one hand, the area of ​​the piston and the annular inner extension surface is reduced and there is always a gap to quickly respond to the connecting gas channel and the driving air groove; on the other hand, the existence of the driving air groove makes the initial driving surface of the piston always larger and capable of driving the piston to slide. The two aspects work together to avoid the problem that the surface of the piston in the prior art directly contacts the surface of the annular connecting part, which results in an excessively large area of ​​the contact surface, resulting in a smaller initial driving surface of the piston and a smaller gap between the two, which makes it impossible to quickly or even directly drive the piston to slide.

[0019] Preferably, the first mounting seat also includes an annular outer extension portion located at the radial outer end of the annular connecting portion, the annular outer extension portion and the annular inner extension portion extend axially in the same direction, the piston is slidingly sealed with the inner wall of the annular outer extension portion, the rod body is slidingly sealed with the inner wall of the annular inner extension portion, and the driving air groove is surrounded by the inner wall of the annular outer extension portion, the surface of the annular connecting portion facing the piston, and the outer wall of the annular inner extension portion.

[0020] With such a configuration, the annular outer extension and the inner wall of the cylinder shell give the actuator a double-wall structure, which on the one hand enhances the structural strength of the actuator, and on the other hand can reduce the size of the piston, and the first mounting seat can be processed separately, making it easier to control its surface roughness, thereby improving the assembly sealing between the piston and the rod body and the mounting seat respectively, while reducing costs. On the other hand, the annular outer extension and the annular outer extension not only respectively realize sliding sealing for the rod body and the piston, but also respectively guide and limit them to cooperate to prevent the piston rod assembly from tilting as a whole during axial sliding.

[0021] Preferably, a first annular sealing groove for accommodating an O-ring is provided on the outer wall of the rod body, and the outer wall of the rod body is slidingly sealed with the inner wall of the annular inner extension through the O-ring. A second annular sealing groove for accommodating an O-ring is provided on the outer wall of the piston, and the outer wall of the piston is slidingly sealed with the inner wall of the annular outer extension through the O-ring.

[0022] In this arrangement, the first annular sealing groove is opened on the outer wall of the rod body to avoid destroying the structural strength of the annular inner extension part. The radial inner side surfaces of the annular inner extension part and the annular connecting part provide a longer sealing surface to meet the longer sliding sealing stroke of the rod body, and the radial width of the annular inner extension part can be made smaller, thereby further reducing the possible abutment area with the piston surface facing the annular inner extension part, making it easier for gas to enter the driving air groove; the second annular sealing groove is opened on the outer wall of the piston to avoid destroying the structural strength of the annular outer extension part, and the annular outer extension part can be made into a thin-walled structure, which on the one hand ensures the space of the driving air groove and the area of ​​the driving surface of the piston, and on the other hand, the inner wall surface of the annular outer extension part provides the piston with a longer sliding sealing stroke.

[0023] Preferably, the axial extension length of the annular inner extension portion is not greater than the axial extension length of the annular outer extension portion, the radial inner side of the annular outer extension portion forms a piston chamber, the driving air groove is at least part of the piston chamber, and at least part of the piston can extend into the driving air groove.

[0024] With such arrangement, the piston chamber serves as a accommodating space for the piston, the annular outer extension portion provides a stroke space for the axial movement of the piston, and at least part of the piston can move to the overlapping area between the annular outer extension portion and the annular inner extension portion, so that the axial movement stroke of the piston is greater than the difference in axial extension length between the annular outer extension portion and the annular inner extension portion. As a result, not only the axial length of the first mounting seat will basically not increase, the height of the entire valve will not increase, the structure will be more compact, and it can also ensure that the piston rod assembly has a large pressing surplus on the diaphragm. Even if the rod body is worn due to long-term collision, the axial movement stroke of the rod body can still ensure that the diaphragm is pressed firmly on the valve seat.

[0025] Preferably, a second mounting seat having the same structure as the first mounting seat is provided on one axial side of the first mounting seat, and the first mounting seat and the second mounting seat are in axial contact with each other;

[0026] The first mounting seat and the second mounting seat are arranged face to face, or the first mounting seat and the second mounting seat are arranged in the same direction.

[0027] In this arrangement, the structure of the second mounting seat is the same as that of the first mounting seat, so that the actuator includes two mounting seats with the same structure, which can save processing costs, and the first mounting seat and the second mounting seat are arranged in a variety of settings in the cylinder shell, corresponding to the switching to form different types of pneumatic diaphragm valves. The first mounting seat has a driving air groove corresponding to one of the pistons, and forms a sliding seal with the piston and the rod body respectively, while the second mounting seat can only play a guiding role for the rod body, and can also have a driving air groove corresponding to the other piston at the same time, with more application scenarios and lower adjustment costs.

[0028] Preferably, the first mounting seat and the second mounting seat both include a positioning groove arranged on the surface away from the annular outer extension portion, and the inner wall of the cylinder shell is provided with a positioning step; the annular outer extension portion of the second mounting seat axially abuts and cooperates with the positioning groove of the first mounting seat, and the annular outer extension portion of the first mounting seat axially abuts and cooperates with the positioning step, thereby achieving coaxiality between the first mounting seat and the second mounting seat, facilitating the rod body to coaxially pass through the first mounting seat and the second mounting seat; or, the positioning groove of the first mounting seat axially abuts and cooperates with the positioning step of the cylinder shell, and the annular outer extension portion of the first mounting seat and the annular outer extension portion of the second mounting seat axially abut and cooperate, so that the limiting between the first mounting seat and the cylinder shell is more stable and the coaxiality is higher, thereby ensuring smooth axial sliding of the rod body in the cylinder shell.

[0029] Preferably, there are two pistons, one piston is arranged between the first mounting seat and the end of the cylinder housing, and the other piston is arranged between the first mounting seat and the second mounting seat, at least a portion of the other piston can be located radially outside the annular inner extension of the second mounting seat, or a portion of the spring is located radially outside the annular inner extension of the second mounting seat.

[0030] In this way, the above structure corresponds to a normally open or normally closed double-piston pneumatic diaphragm valve, so that the driving gas can be used to stably and quickly drive the piston rod assembly to move axially to open and close the pneumatic diaphragm valve, and the response speed is faster. The space radially outside the annular inner extension of the second mounting seat can accommodate a piston or spring, making the overall structure of the diaphragm valve more compact.

[0031] Preferably, the gas passage is formed in the rod body and includes a main passage extending axially and a bypass passage intersecting and communicating with the main passage. The main passage is connected to an external gas source, and the bypass passage is connected to the drive gas groove. This arrangement shortens the gas passage's flow path, allowing gas from the external gas source to quickly reach the drive gas groove through the passage, enabling rapid axial sliding of the piston rod assembly and a faster response speed for the pneumatic diaphragm valve.

[0032] Preferably, the annular inner extension is provided with a guide portion. When the piston abuts the annular inner extension, the bypass channel communicates with the drive air groove via the guide portion. This configuration facilitates easier and faster communication between the drive air groove and the bypass channel, thereby improving the response speed of the pneumatic diaphragm valve.

[0033] Preferably, the rod body includes a first rod and a second rod that can abut each other axially, the end of one of the first rod and the second rod has a connecting groove, and the other is provided with the bypass channel, when the end of the other extends into the connecting groove, the bypass channel is at least partially located in the connecting groove and the two are connected.

[0034] With this arrangement, the first rod and the second rod are of a split structure, which is convenient for processing and installation, and the first rod and the second rod are axially abutted and can move axially synchronously. By setting a connecting groove, the overall length of the rod body can be shortened, thereby reducing the overall height of the pneumatic diaphragm valve and reducing costs; and the connecting groove connects the bypass pipe and the driving air groove. The three are connected and work together to enable the gas to quickly enter the driving air groove, thereby ensuring the response speed of the pneumatic diaphragm valve.

[0035] Preferably, the top end of the valve body has a recessed portion, the annular valve seat and the diaphragm are both located in the recessed portion, and the first fluid channel and the second fluid channel are respectively communicated with the recessed portion.

[0036] With such a configuration, the recess can act as a radial limit for the diaphragm, so that the center of the diaphragm is basically coaxial with the center of the annular valve seat, thereby improving the sealing effect after the diaphragm and the annular valve seat abut against each other; at the same time, the recess can also shorten the overall height of the pneumatic diaphragm valve, making the overall structure of the valve more compact.

[0037] Preferably, the spring elastically abuts against a surface of the piston, and the axial projection area of ​​the driving surface is S0. When the diaphragm abuts and seals against the annular valve seat, the diaphragm has a positive pressure surface corresponding to the annular valve seat and connected to the first fluid channel, and a back pressure surface located on the outer peripheral side of the positive pressure surface and connected to the second fluid channel. The axial projection area of ​​the positive pressure surface is S1, and the axial projection area of ​​the back pressure surface is S2, satisfying the following conditions: S0>1.5S1, S0>1.5S2.

[0038] With this arrangement, the area of ​​the driving surface is set larger, and the contact area between the driving surface and the gas is also larger. The driving pressure is increased while the pressure of the driving gas source remains constant. That is, the axial sliding of the piston rod assembly can be effectively achieved without changing the pressure of the driving gas source, thereby making the pneumatic diaphragm valve respond quickly.

[0039] In summary, compared with the prior art, the present invention has at least the following beneficial effects:

[0040] In the pneumatic diaphragm valve of the present invention, the rod body in the piston rod assembly passes through the inner side of the axially extending annular inner extension part, so the piston rod assembly is guided by the axial thickness of the annular connection part and the axial height of the annular inner extension part when sliding axially. Compared with the prior art, the annular inner extension part increases the guide surface height / axial length of the first mounting seat to the rod body, which can effectively guide to prevent the rod body from tilting. At the same time, since the annular inner extension part extends axially to a predetermined height relative to the upper or lower surface of the annular connection part, the surface of the annular inner extension part facing the piston and the surface of the annular connection part facing the piston have an axial height difference, and the axial movement of the piston rod assembly can abut against the annular inner extension part to limit, so that there is always a large space driving air groove between the annular connection part and the piston. Since the gas needs to pass through the surface of the annular inner extension toward the piston The piston rod assembly can be driven axially by the piston, and the gap can be further increased so that the upper or lower surface of the piston basically constitutes the driving surface, thereby achieving rapid response and long service life of the pneumatic diaphragm valve, and avoiding the problem in the prior art that the initial driving surface is small due to the abutment between the surface of the piston and the surface of the annular connecting part, and the gap between the two is small, and the piston cannot be driven to slide quickly or even directly. BRIEF DESCRIPTION OF THE DRAWINGS

[0041] In order to more clearly illustrate the specific implementation methods of the utility model or the technical solutions in the prior art, the drawings required for use in the specific implementation methods or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are some implementation methods of the utility model. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0042] Figure 1This is a cross-sectional schematic diagram of a pneumatic diaphragm valve (single piston) according to an embodiment of the present invention, wherein the pneumatic diaphragm valve is a normally closed diaphragm valve.

[0043] Figure 2 for Figure 1 A cross-sectional schematic diagram of a normally closed diaphragm valve, wherein the first mounting seat includes an annular outer extension.

[0044] Figure 3 This is a cross-sectional schematic diagram of a pneumatic diaphragm valve (double piston) according to an embodiment of the present invention, wherein the pneumatic diaphragm valve is a normally closed diaphragm valve.

[0045] Figure 4 This is a cross-sectional schematic diagram of a pneumatic diaphragm valve (double piston) according to another embodiment of the present invention, wherein the pneumatic diaphragm valve is a normally open diaphragm valve.

[0046] Figure 5 This is an axonometric view of the first mounting base shown in an embodiment of the present utility model.

[0047] Description of Reference Numerals

[0048] 10. Valve body; 11. First fluid channel; 12. Second fluid channel; 13. Recess;

[0049] 20. Annular valve seat;

[0050] 30. Diaphragm;

[0051] 40. Actuator; 41. Cylinder housing; 411. Positioning step; 42. Piston rod assembly; 421. Piston; 4211. Driving surface; 4212. Second annular sealing groove; 422. Rod body; 4221. First rod; 4222. Second rod; 4223. First annular sealing groove; 4224. Connecting groove; 423. Gas channel; 4231. Main channel; 4232. Bypass channel; 43. Spring; 44. Diaphragm pressing member; 45. First mounting seat; 451. Annular connecting portion; 452. Annular inner extension portion; 453. Annular outer extension portion; 454. Piston chamber; 455. Driving gas groove; 456. Positioning groove; 457. Conducting portion; 46. Second mounting seat. DETAILED DESCRIPTION

[0052] The following is a clear and complete description of the technical solution of the present invention in conjunction with the accompanying drawings. Obviously, the embodiments described are only some of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making any creative efforts are within the scope of protection of the present invention.

[0053] In the description of this utility model, it should be noted that the terms "center," "upper," "lower," "left," "right," "vertical," "horizontal," "inner," and "outer," etc., indicating positions or relationships, are based on the positions or relationships shown in the accompanying drawings and are intended solely to facilitate the description of this utility model and simplify the description. They do not indicate or imply that the devices or components referred to must have a specific orientation, be constructed, or operate in a specific orientation. Therefore, they should not be construed as limitations on this utility model. Furthermore, the terms "first," "second," and "third" are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0054] In the description of this utility model, it should be noted that, unless otherwise expressly specified or limited, the terms "mounted," "connected," and "connected" should be understood in a broad sense. For example, they can refer to fixed connections, detachable connections, or integral connections; mechanical connections, electrical connections; direct connections, indirect connections through an intermediate medium, and internal communication between two components. Those skilled in the art will understand the specific meanings of the above terms in this utility model based on the specific circumstances.

[0055] As attached Figure 1-4 As shown, a pneumatic diaphragm valve according to an embodiment of the present invention includes a valve body 10, an annular valve seat 20, a diaphragm 30, and an actuator 40. The valve body 10 includes a first fluid channel 11 and a second fluid channel 12. The annular valve seat 20 is disposed on the valve body 10 and surrounds the outer circumference of the top end of the first fluid channel 11. The first fluid channel 11 and the second fluid channel 12 are connected via the annular valve seat 20. The first fluid channel 11 can be a fluid inflow channel, and the second fluid channel 12 can be a fluid outflow channel. The fluids are process gases used in semiconductor manufacturing processes.

[0056] The diaphragm 30 is elastically deformable and sealably mounted on the valve body 10 above the annular valve seat 20. Specifically, the outer edge of the diaphragm 30 is pressed and sealed. The actuator 40 is connected to the top of the valve body 10 and also located above the diaphragm 30. It is used to apply or remove axial force to the diaphragm 30, causing it to abut or move away from the annular valve seat 20, thereby closing or opening the diaphragm valve. The diaphragm 30 is made of metal with an appropriate thickness to provide sufficient strength and elasticity, such as nickel-cobalt alloy or stainless steel. The annular valve seat 20 is made of plastic, such as PFA, PTFE, or PTCFE.

[0057] Specifically, the actuator 40 includes a cylinder housing 41 connected to the top of the valve body 10, a piston rod assembly 42 disposed within the cylinder housing 41, and a spring 43 that elastically presses against the piston rod assembly 42. The piston rod assembly 42 is axially movable above the diaphragm 30, and the piston rod assembly 42 can directly or indirectly press against the diaphragm 30. In this embodiment, a diaphragm pressing member 44 is axially movable above the diaphragm 30 and disposed between the piston rod assembly 42 and the diaphragm 30. The piston rod assembly 42 is axially movable above the diaphragm pressing member 44. Intake and exhaust are used to move the piston rod assembly 42 toward or away from the diaphragm pressing member 44, causing the diaphragm pressing member 44 to press against or away from the diaphragm 30, thereby causing the diaphragm 30 to abut or separate from the annular valve seat 20 to close or open the diaphragm valve. Of course, in other embodiments, the diaphragm pressing member 44 may not be provided, and the piston rod assembly 42 moves closer to or farther away from the diaphragm 30 , directly pressing against or leaving the diaphragm 30 , to achieve opening and closing of the diaphragm valve.

[0058] In this embodiment, the top of the valve body 10 has a recessed portion 13 with an upward opening. The annular valve seat 20 and the diaphragm 30 are both accommodated within the recessed portion 13. The first fluid channel 11 and the second fluid channel 12 are respectively connected to the recessed portion 13. The recessed portion 13 can radially limit the diaphragm 30, so that the center of the diaphragm 30 is substantially coaxial with the center of the annular valve seat 20, thereby improving the sealing effect after the diaphragm 30 and the annular valve seat 20 abut. At the same time, the accommodation function of the recessed portion 13 can also shorten the overall height of the pneumatic diaphragm valve, making the overall structure of the valve more compact. Of course, in other embodiments, the top of the valve body 10 may not have the recessed portion 13. Instead, the annular valve seat 20 is directly disposed on the plane of the top surface of the valve body 10. The cylinder housing 41 of the actuator 40 is used to seal the valve body 10 and seal the diaphragm 30. The first fluid channel 11 and the second fluid channel 12 are respectively connected to the annular valve seat 20.

[0059] As attached Figure 1-3As shown, the pneumatic diaphragm valve of the embodiment of the present invention is a normally closed valve, that is, the spring 43 is arranged on the side of the piston rod assembly 42 away from the diaphragm 30. When the driving gas is not passed, the spring 43 pushes the piston rod assembly 42 and the diaphragm pressing member 44 toward the diaphragm 30 due to the compressed rebound force, so that the diaphragm pressing member 44 abuts against the diaphragm 30, the diaphragm 30 is deformed and sealed against the annular valve seat 20, the first fluid channel 11 and the second fluid channel 12 are disconnected, and the diaphragm valve is in a closed state at this time; when the driving gas is passed, the spring 43 pushes the piston rod assembly 42 and the diaphragm pressing member 44 toward the diaphragm 30 due to the compressed rebound force, so that the diaphragm pressing member 44 abuts against the diaphragm 30, the diaphragm 30 is deformed and sealed against the annular valve seat 20, and the first fluid channel 11 and the second fluid channel 12 are disconnected. At this time, the diaphragm valve is in a closed state; when the driving gas is passed, the spring 43 pushes the piston rod assembly 42 and the diaphragm pressing member 44 toward the diaphragm 30. After the driving gas, the driving gas is generally an inert gas. The upward force of the driving gas on the piston rod assembly 42 is greater than the downward force of the spring 43 on the piston rod assembly 42. The piston rod assembly 42 moves axially upward to move away from the diaphragm 30. The piston rod assembly 42 removes the squeezing effect on the diaphragm pressing member 44. The diaphragm 30 recovers under the action of its own restoring force and the force of the process gas between the first fluid channel 11 and the second fluid channel 12, pushing up the diaphragm pressing member 44, and the diaphragm valve is in the open state. It can be understood that the axial direction mentioned herein refers to Figure 1-3 The vertical direction in .

[0060] For a normally closed valve, after long-term use and multiple impacts, the bottom end of the piston rod assembly 42 and the top end of the diaphragm pressing member 44 will be worn. The piston rod assembly will move downward under the action of the compression spring 43 and the weight of the piston rod assembly 42. The axial opposing surfaces of the horizontal part of the piston and the mounting seat are very close or against each other, thereby reducing the area of ​​the initial driving surface of the piston and affecting the opening and closing of the valve by the driving gas.

[0061] As attached Figure 4 As shown, the pneumatic diaphragm valve of the embodiment of the present invention can also be a normally open valve, that is, the spring 43 is arranged on the side of the piston rod assembly 42 close to the diaphragm 30. When there is no ventilation or exhaust, the spring 43 pushes the piston rod assembly 42 and the diaphragm pressing member 44 in the direction away from the diaphragm 30, so that the diaphragm pressing member 44 does not abut against the diaphragm 30, the diaphragm 30 is not deformed, and the first fluid channel 11 and the second fluid channel 12 are connected, and the pneumatic diaphragm valve is in an open valve state; after ventilation, the downward force of the driving gas on the piston rod assembly 42 is greater than the upward force of the spring 43 on the piston rod assembly 42, the piston rod assembly 42 moves axially downward rapidly, abuts against the diaphragm pressing member 44, and then the diaphragm pressing member 44 abuts against the diaphragm 30, the diaphragm 30 is deformed and sealed against the annular valve seat 20, the first fluid channel 11 and the second fluid channel 12 are disconnected, and the pneumatic diaphragm valve is in a closed valve state.

[0062] For a normally open valve, it is necessary to precisely control the force of the spring 43. If the force of the compression spring 43 is too small, the piston rod assembly 42 cannot be lifted to an appropriate height for a long time, and the piston rod assembly 42 presses down the diaphragm pressing member 44, causing the normally open diaphragm valve to fail. If the force of the compression spring 43 is too large, the axially opposing surfaces of the horizontal part of the piston and the mounting seat will offset each other, thereby reducing the area of ​​the initial driving surface of the piston and affecting the opening and closing of the valve by the driving gas.

[0063] Therefore, whether it is a normally closed valve or a normally open valve, the actuator 40 of this embodiment of the present invention also includes a first mounting seat 45 arranged in the cylinder housing 41, and the first mounting seat 45 includes an annular connecting portion 451 and an annular inner extension portion 452 axially extending and arranged at the radial inner end of the annular connecting portion 451. It should be noted that the annular inner extension portion 452 is a portion axially extending and protruding to a predetermined height on the upper or lower surface of the radial inner end of the annular connecting portion 451, and the dividing line between the annular inner extension portion 452 and the annular connecting portion 451 is a virtual dotted line in the figure.

[0064] The piston rod assembly 42 includes a gas channel 423, a rod body 422 and a piston 421 fixed on the outer wall of the rod body 422. The rod body 422 can slide through the inner side of the annular inner extension portion 452. Therefore, the axial height formed by the inner side wall of the annular connecting portion 451 and the annular inner extension portion 452 jointly guides the rod body 422. Therefore, compared with the existing technology, the annular inner extension portion 452 increases the guide surface height of the first mounting portion to the rod body 422, which can effectively guide the rod body 422 to prevent tilting.

[0065] At the same time, due to the axial protrusion of the annular inner extension 452, a driving air groove 455 is formed between the annular connecting portion 451 and the piston 421, which is located radially outside the annular inner extension 452. The driving air groove 455 is used to communicate with the gas channel 423. The surface of the piston 421 facing the driving air groove 455 is the driving surface 4211. The driving surface 4211 refers to the upper or lower surface of the piston 421. For example, in a normally closed diaphragm valve, it refers to the lower surface of the piston 421. Even if a groove is provided on the lower surface of the piston 421, the bottom surface of the groove can also be a part of the driving surface 4211. In short, the driving surface 4211 is the surface in contact with the driving gas. The part of the driving surface 4211 facing the driving air groove 455 is the initial driving surface. The driving surface 4211 is used to contact with the driving gas to drive the piston rod assembly 42 to move axially up and down, and the piston rod assembly 42 can abut against the annular inner extension 452 to limit the position.

[0066] Therefore, there is an axial height difference between the surface of the annular inner extension 452 facing the piston 421 and the surface of the annular connecting portion 451 facing the piston 421. As a result, there is always a driving gas groove 455 between the annular connecting portion 451 and the piston 421, and the gas channel 423 is located inside the rod body 422, and the driving gas groove 455 is located on the radial outside of the annular inner extension 452. Therefore, the gas needs to pass through the surface of the annular inner extension 452 to enter the driving gas groove 455. The upper or lower surface of the annular inner extension 452 is smaller than the upper or lower surface of the horizontal part of the prior art. Even if the opposing surfaces of the piston 421 and the annular inner extension 452 are against each other, the area of ​​the opposing surfaces is smaller, and it is more likely to have a gap. Moreover, due to the driving gas groove 455, the piston 421 and the annular inner extension 452 are not in contact with each other. 55 always exists, so that there is an initial effective driving surface 4211 of a certain size (at least the surface area corresponding to the piston 421 and the driving gas groove 455). As long as a small amount of driving gas directly enters the driving gas groove 455 through the gap and acts on the initial effective driving surface 4211 of the piston 421, the piston rod assembly 42 can be driven axially under constant gas pressure, further increasing the gap between the piston 421 and the annular inner extension 452, and further increasing the surface of the piston 421 facing the annular inner extension 452 to become the effective driving surface 4211, so that the entire surface of the piston 421 facing the first mounting seat 45 is basically the effective driving surface 4211, thereby achieving rapid response and service life of the pneumatic diaphragm valve.

[0067] Based on the use principle of the spring 43 and the gas-driven piston 421, the spring 43 and the driving air groove 455 are respectively located on both axial sides of the piston 421. The area of ​​the initial effective driving surface 4211 on the surface of the piston 421 will affect the response speed and ability of the pneumatic diaphragm valve. Therefore, by axially extending the surface of the annular connecting portion 451 and protruding from the axial extension length of the surface of the annular connecting portion 451, the annular inner extension 452 not only ensures that there is sufficient guide surface to prevent the rod body 422 from tilting, but also can limit the surface of the piston 421 and abut it, so that there is always a driving air groove 455 on the radial outside of the annular inner extension 452, thereby ensuring that the area corresponding to the piston 421 surface and the driving air groove 455 is always a sufficiently large initial effective driving surface 4211. The small abutment surface between the piston 421 and the annular inner extension 452 makes it easy for the driving gas to enter the driving air groove 455 and squeeze the effective driving surface 4211.

[0068] In the attached Figure 1 and attached Figure 2In the two illustrated embodiments, the first mounting seat 45 further includes an annular outer extension 453 located at the radially outer end of the annular connecting portion 451. The piston 421 is in sliding seal with the inner wall of the annular outer extension 453, and the rod 422 is in sliding seal with the inner wall of the annular inner extension 452. The driving air groove 455 is surrounded by the inner wall of the annular outer extension 453, the surface of the annular connecting portion 451, and the outer wall of the annular inner extension 452. In other embodiments, the annular outer extension 453 may not be provided, and the piston 421 may be directly in sliding seal with the cylinder housing 41. The driving air groove 455 may be formed by the annular connecting portion 451, the annular inner extension 452, and the inner wall of the cylinder housing 41. In this case, the inner side surface of the outer end of the annular connecting portion 451 must be sealed with the inner wall of the cylinder housing 41, and the specific sealing connection method is not limited.

[0069] The advantage of providing an annular outer extension 453 is that it allows the actuator 40 to form a double-walled housing, which not only enhances the structural strength of the actuator 40 but also reduces the size of the piston 421. Furthermore, the first mounting seat 45 can be machined separately, making it easier to control its surface roughness, thereby improving the sealing between it and the piston 421 and the rod 422, respectively, while also reducing costs. The first mounting seat 45 can be made of a different material from the cylinder housing 41. For example, if the cylinder housing 41 is made of metal and the first mounting seat 45 is made of resin, it is easier to machine and more cost-effective. Alternatively, the first mounting seat 45 and the cylinder housing 41 can be made of the same material, both metal.

[0070] When the annular outer extension 453 is provided, the piston 421 is slidably sealed with the annular outer extension 453. In order to ensure the space of the driving air groove 455 and the area of ​​the driving surface 4211, and to avoid the diameter of the cylinder housing 41 being too large, thereby increasing costs, the annular outer extension 453 is designed to have a thin-walled structure. Therefore, a second annular sealing groove 4212 for accommodating an O-ring is provided on the outer wall of the piston 421, and the outer wall of the piston 421 is slidably sealed with the inner wall of the annular outer extension 453 through the O-ring. Similarly, while ensuring the structural strength of the annular inner extension 452, the radial width of the annular inner extension 452 is reduced as much as possible to reduce the diameter of the cylinder housing 41, making the structure more compact and the cost lower. It can also further reduce the possible contact area with the surface of the piston 421, making it easier for gas to enter the driving gas groove 455. Therefore, the first annular sealing groove 4223 is opened on the outer wall of the rod body 422, and the outer wall of the rod body 422 is slidably sealed with the inner wall of the annular inner extension 452 through an O-ring. The radial inner side of the annular inner extension 452 and the annular connecting portion 451 provides a longer sealing surface, and the sealing effect and guiding effect are better.

[0071] More preferably, a piston chamber 454 is formed on the radial inner side of the annular outer extension 453 as a receiving space for the piston 421. The annular outer extension 453 provides a stroke space for the axial movement of the piston 421. At least a portion of the piston 421 can extend into the driving air groove 455, that is, into the axial overlapping area between the annular inner extension 452 and the annular outer extension 453. This can be achieved by providing a groove for accommodating the annular inner extension 452 on the surface of the piston 421 facing the annular inner extension 452; the axial extension length of the annular inner extension 452 is not greater than the axial length of the annular outer extension 453. The driving air groove 455 is at least a part of the piston chamber 454, so that the axial movement stroke of the piston 421 is greater than the axial extension length difference between the annular outer extension portion 453 and the annular inner extension portion 452. As a result, not only the axial length of the first mounting seat 45 will not increase basically, the height of the entire valve will not increase, the structure will be more compact, and it can also ensure that the piston rod assembly 42 has a large pressing surplus on the diaphragm. Even if the rod body 422 is worn due to long-term collision, the axial movement stroke of the rod body 422 can still ensure that the diaphragm 30 is pressed firmly on the annular valve seat 20.

[0072] In some embodiments, a second mounting seat 46 having the same structure as the first mounting seat 45 is further provided in the cylinder housing 41. It should be noted that the first mounting seat 45 refers to a mounting seat having a driving gas groove 455 and capable of communicating with the gas channel 423 through the driving gas groove 455; if the driving gas groove 455 of the mounting seat is not connected to the gas channel 423, it is not considered to be the first mounting seat 45; of course, in some implementations, the driving gas groove 455 of the second mounting seat 46 may also be connected to the gas channel 423.

[0073] In the attached Figure 1 In the illustrated embodiment, a second mounting seat 46 is provided axially below the first mounting seat 45. The first and second mounting seats 45, 46 are arranged in the same orientation (both facing upward) and in axial abutment with each other. In this embodiment, there are two pistons 421: one piston 421 is positioned between the first mounting seat 45 and the end of the cylinder housing 41, and the other piston 421 is positioned between the first and second mounting seats 45, 46. The first mounting seat 45 has a driving air groove 455 corresponding to one piston 421, and the second mounting seat 46 also has a driving air groove 455 corresponding to the other piston 421.

[0074] exist Figure 1In the illustrated embodiment of a normally closed diaphragm valve, both the first mounting seat 45 and the second mounting seat 46 include a positioning groove 456 disposed on a surface facing away from the annular outer extension 453, and a positioning step 411 is provided on the inner wall of the cylinder housing 41. The annular outer extension 453 of the second mounting seat 46 axially abuts and cooperates with the positioning groove 456 of the first mounting seat 45, thereby achieving coaxiality between the first mounting seat 45 and the second mounting seat 46, facilitating the rod body 422 to pass through the first and second mounting seats 45, 46. Simultaneously, the annular outer extension 453 of the first mounting seat 45 abuts against the positioning step 411 on the inner wall of the cylinder housing 41, thereby making the positional limitation between the first mounting seat 45 and the cylinder housing 41 more stable and achieving higher coaxiality, thereby ensuring smooth axial sliding of the rod body 422 within the cylinder housing 41.

[0075] like Figure 1 As shown, in this embodiment, one end of the spring 43 elastically abuts against the upper surface of the piston 421, and the other end elastically abuts against the cylinder housing 41. At least a portion of the piston 421 can be located radially outside the annular inner extension 452 of the first mounting seat 45, and at least a portion of the other piston 421 can be located radially outside the annular inner extension 452 of the second mounting seat 46. The double-piston structure enables the pneumatic diaphragm valve to stably drive the piston rod assembly 42 to move axially under the action of the driving gas.

[0076] In the attached Figure 2 In the embodiment shown, a second mounting seat 46 is provided axially below the first mounting seat 45, and the first mounting seat 45 and the second mounting seat 46 are arranged face to face and axially abut. In this embodiment, there are two pistons 421, a piston 421 is arranged between the first mounting seat 45 and the end of the cylinder housing 41, and another piston 421 is arranged between the first mounting seat 45 and the second mounting seat 46. The first mounting seat 45 has a driving air groove 455 corresponding to one piston 421 and forms a sliding seal with the rod body 422. Although the second mounting seat 46 has a driving air groove 455 corresponding to the other piston 421, the driving air groove 455 is not connected to the gas channel 423, and the second mounting seat 46 can only play a guiding role for the rod body 422 and the other piston 421.

[0077] Similarly, the first mounting seat 45 and the second mounting seat 46 both include a positioning groove 456 arranged on the surface away from the annular outer extension 453, and the inner wall of the cylinder shell 41 is provided with a positioning step 411. In this embodiment, the annular outer extension 453 of the first mounting seat 45 and the second mounting seat 46 abut against each other, and the positioning groove 456 of the first mounting seat 45 is axially abutted against the positioning step 411 of the cylinder shell 41, so that the limitation between the first mounting seat 45 and the cylinder shell 41 is more stable and the coaxiality is higher, thereby ensuring that the rod body 422 slides smoothly axially in the cylinder shell 41.

[0078] like Figure 2As shown, in this embodiment, one end of the spring 43 elastically abuts against the lower surface of the piston 421, and the other end abuts against the second mounting seat 46. Furthermore, at least a portion of the piston 421 can be located radially outside the annular inner extension 452 of the first mounting seat 45, and a portion of the spring 43 is located radially outside the annular inner extension 452 of the second mounting seat 46. The annular inner extension 452 of the second mounting seat 46 serves to radially limit the spring 43. At the same time, the dual-piston structure enables the pneumatic diaphragm valve to enable the driving gas to stably drive the piston rod assembly 42 to move axially, and the pneumatic diaphragm valve has a faster response speed.

[0079] As attached Figure 1 and attached Figure 2 In the two embodiments shown, the gas channel 423 is opened in the rod body 422, and the gas channel 423 includes a main channel 4231 extending axially and a bypass channel 4232 intersecting and connected to the main channel 4231. The main channel 4231 is connected to an external gas source, and the bypass channel 4232 is connected to the driving gas groove 455. The flow path of the above-mentioned gas channel 423 is relatively short, and the gas from the external gas source can quickly reach the driving gas groove 455 through the gas channel 423, so that the piston rod assembly 42 slides axially quickly, and the pneumatic diaphragm valve has a faster response speed.

[0080] More preferably, the annular inner extension 452 is provided with a conducting portion 457, which can be a chamfered angle or a rounded angle provided on the inner edge of the annular inner extension 452, further reducing the abutment surface area of ​​the annular inner extension 452 toward the piston 421 to form more gaps. Of course, it can also be a through groove extending radially through the annular inner extension 452. When the piston 421 abuts against the annular inner extension 452, the bypass channel 4232 is connected to the driving air groove 455 via the conducting portion 457, ensuring that the connectivity between the bypass channel 4232 and the driving air groove 455 is not affected by the spring 43 or the rod body 422, thereby ensuring that the response speed of the pneumatic diaphragm valve is always high and the service life is longer.

[0081] As a preferred embodiment, Figure 1 and Figure 2As shown, the rod body 422 includes a first rod 4221 and a second rod 4222 that can axially abut each other, that is, the first rod 4221 and the second rod 4222 are a split structure, the first rod 4221 and the second rod 4222 are axially abutted and can move axially synchronously, such a structure makes the rod body 422 and the piston 421 on its outer periphery easier to process and assemble, and the production cost is lower; and the connecting groove 4224 connects the bypass channel 4232 and the driving gas groove 455, so that the gas can quickly enter the driving gas groove 455, ensuring the response speed of the pneumatic diaphragm valve. At the same time, since one end of the bypass channel 4232 of the first rod 4221 or the second rod 4222 is embedded in the connecting groove 4224 of the other, it plays a role of radial limiting, which not only shortens the axial length of the first rod 4221 and the second rod 4222 after abutting, but also ensures that the main channels 4231 in the first rod 4221 and the second rod 4222 are aligned and connected, so that the gas can be smoothly input and output.

[0082] Based on the above description, for the pneumatic diaphragm valve, adjusting the force of the spring 43 can achieve effective sealing between the diaphragm 30 and the annular valve seat 20, and the sealing will not be lost due to the gas pressure of the first fluid channel 11 and the second fluid channel 12. However, it often makes it difficult for the driving gas to effectively lift the piston 421 and the valve cannot be opened. The factory needs to increase the pressure of the driving gas to increase the driving pressure of the driving gas. However, the driving gas source provided by the factory is a constant pressure, because it not only provides driving gas to the valve, but also provides the system to other parts of the system in which the valve is used. Therefore, an independent gas source needs to be set up to provide the valve with a gas source with increased pressure. This is very troublesome and costly. Even if an independent gas source is added, it is difficult to control the pressure of the gas source so that the driving force of the driving gas is sufficient to overcome the force of the spring 43, which brings a lot of trouble to use.

[0083] Therefore, as a preferred embodiment of the present invention, the projected area of ​​the driving surface 4211 in the axial direction is S0. If it is a single piston or multiple pistons, S0 is the sum of the surfaces of all pistons in contact with the driving gas. Figure 3As shown, the diaphragm 30 has a positive pressure surface corresponding to the annular valve seat 20 and connected to the first fluid channel 11, and a back pressure surface located on the outer peripheral side of the positive pressure surface and connected to the second fluid channel 12. The positive pressure surface and the back pressure surface are distinguished by the sealing point where the diaphragm 30 and the annular valve seat 20 are against each other. The projected area of ​​the positive pressure surface in the axial direction is S1, and the projected area of ​​the back pressure surface in the axial direction is S2. The following conditions are met: S0>1.5S1, S0>1.5S2. Therefore, the area of ​​S0 is set to be larger, and the contact area between the driving surface 4211 and the gas is also larger. When the pressure of the driving gas source remains constant, the driving pressure is increased. In the pneumatic diaphragm valve, the spring 43 provides a large force to press the diaphragm and the valve seat to maintain the valve seal. The pneumatic diaphragm valve of the utility model can adapt to a smaller driving gas source, that is, the piston rod assembly 42 can be effectively axially slid without changing the pressure of the driving gas source, thereby making the pneumatic diaphragm valve respond effectively.

[0084] The above-mentioned embodiments are only preferred embodiments of the present invention and cannot be used to limit the scope of protection of the present invention. Any non-substantial changes and replacements made by technicians in this field on the basis of the present invention fall within the scope of protection required by the present invention.

Claims

1. A pneumatic diaphragm valve, comprising: A valve body having a first fluid passage and a second fluid passage; an annular valve seat, disposed on the valve body and surrounding an outer peripheral side of a top end of the first fluid channel, the first fluid channel and the second fluid channel being connected via the annular valve seat; a diaphragm, elastically deformable, sealingly disposed on the valve body and located above the annular valve seat; an actuator for applying or removing an axial force on the diaphragm so that the diaphragm abuts against or leaves the annular valve seat, thereby closing or opening the diaphragm valve; The actuator comprises a cylinder housing connected to the top end of the valve body, a piston rod assembly disposed in the cylinder housing, and a spring elastically pressing against the piston rod assembly, wherein the piston rod assembly is axially movable and located above the diaphragm; and is characterized in that: The actuator further includes a first mounting seat provided in the cylinder housing, the first mounting seat including an annular connecting portion and an annular inner extending portion axially extending and provided at a radial inner end of the annular connecting portion; The piston rod assembly includes a gas channel, a rod body, and a piston fixed to the outer wall of the rod body, wherein the rod body can slidably pass through the inner side of the annular inner extension; A driving air groove is formed between the annular connecting portion and the piston and is located radially outside the annular inner extension portion. The driving air groove is used to communicate with the gas channel. The surface of the piston facing the driving air groove is the driving surface. The driving surface is used to contact with the driving gas to drive the piston rod assembly to move axially up and down. The piston rod assembly can abut against the annular inner extension portion to limit the position.

2. The pneumatic diaphragm valve according to claim 1, characterized in that: The first mounting seat also includes an annular outer extension portion located at the radial outer end of the annular connecting portion, the annular outer extension portion and the annular inner extension portion extend axially in the same direction, the piston is slidingly sealed against the inner wall of the annular outer extension portion, the rod body is slidingly sealed against the inner wall of the annular inner extension portion, and the driving air groove is surrounded by the inner wall of the annular outer extension portion, the surface of the annular connecting portion facing the piston, and the outer wall of the annular inner extension portion.

3. The pneumatic diaphragm valve according to claim 2, characterized in that: A first annular sealing groove for accommodating an O-ring is provided on the outer wall of the rod body, and the outer wall of the rod body is slidingly sealed with the inner wall of the annular inner extension through the O-ring. A second annular sealing groove for accommodating an O-ring is provided on the outer wall of the piston, and the outer wall of the piston is slidingly sealed with the inner wall of the annular outer extension through the O-ring.

4. The pneumatic diaphragm valve according to claim 2, characterized in that: The axial extension length of the annular inner extension portion is no greater than the axial extension length of the annular outer extension portion, the radial inner side of the annular outer extension portion forms a piston chamber, the driving air groove is located in at least a portion of the piston chamber, and at least a portion of the piston can extend into the driving air groove.

5. The pneumatic diaphragm valve according to claim 2, characterized in that: A second mounting seat having the same structure as the first mounting seat is provided on one axial side of the first mounting seat, and the first mounting seat and the second mounting seat are axially abutted against each other; The first mounting seat and the second mounting seat are arranged face to face, or the first mounting seat and the second mounting seat are arranged in the same direction.

6. The pneumatic diaphragm valve according to claim 5, characterized in that: The first mounting seat and the second mounting seat each include a positioning groove provided on a surface facing away from the annular outer extension portion, and the inner wall of the cylinder housing is provided with a positioning step; The annular outer extension of the second mounting seat is axially abutted against the positioning groove of the first mounting seat, and the annular outer extension of the first mounting seat is axially abutted against the positioning step, or the positioning groove of the first mounting seat is axially abutted against the positioning step of the cylinder shell, and the annular outer extension of the first mounting seat and the annular outer extension of the second mounting seat are axially abutted against each other.

7. The pneumatic diaphragm valve according to claim 5, characterized in that: There are two pistons, one of which is arranged between the first mounting seat and the end of the cylinder housing, and the other of which is arranged between the first mounting seat and the second mounting seat. At least a portion of the other of the pistons can be located radially outside the annular inner extension of the second mounting seat, or a portion of the spring is located radially outside the annular inner extension of the second mounting seat.

8. The pneumatic diaphragm valve according to claim 1 or 2, characterized in that: The gas channel is opened in the rod body, and includes a main channel extending along the axial direction and a bypass channel intersecting and communicating with the main channel. The main channel is communicated with an external gas source, and the bypass channel is communicated with the driving gas groove.

9. The pneumatic diaphragm valve according to claim 8, characterized in that: The annular inner extension portion is provided with a conducting portion. When the piston abuts against the annular inner extension portion, the bypass channel is communicated with the driving air groove via the conducting portion.

10. The pneumatic diaphragm valve according to claim 9, characterized in that: The rod body includes a first rod and a second rod that can abut each other axially, the end of one of the first rod and the second rod has a connecting groove, and the other is provided with the bypass channel. When the end of the other extends into the connecting groove, the bypass channel is at least partially located in the connecting groove and the two are connected.

11. The pneumatic diaphragm valve according to claim 1, wherein: The top end of the valve body has a recessed portion, the annular valve seat and the diaphragm are both located in the recessed portion, and the first fluid channel and the second fluid channel are respectively connected to the recessed portion; And / or, the spring elastically abuts against a surface of the piston, the axial projection area of ​​the driving surface is S0, and when the diaphragm abuts and seals against the annular valve seat, the diaphragm has a positive pressure surface corresponding to the annular valve seat and connected to the first fluid channel, and a back pressure surface located on the outer peripheral side of the positive pressure surface and connected to the second fluid channel, the axial projection area of ​​the positive pressure surface is S1, and the axial projection area of ​​the back pressure surface is S2, satisfying the following conditions: S0>1.5S1, S0>1.5S2.

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