Pneumatic diaphragm valve

Abstract

The utility model discloses a pneumatic diaphragm valve which comprises a valve body, an annular valve seat, a diaphragm and a pneumatic actuating assembly, the pneumatic actuating assembly comprises a cylinder shell connected to the top end of the valve body, a piston rod arranged in the cylinder shell, a spring elastically abutting against the piston rod and a diaphragm pressing piece arranged above the diaphragm in an axial moving mode, and meanwhile the annular valve seat is arranged on the diaphragm pressing piece. The buffer piece is arranged between the piston rod and the diaphragm pressing piece, in the valve opening and closing process, the piston rod makes contact with the diaphragm pressing piece through the buffer piece, hard collision between the piston rod and the diaphragm pressing piece is avoided, impact force is absorbed, and abrasion of the piston rod and the diaphragm pressing piece is avoided or little. The piston rod moves by a preset distance to drive the diaphragm pressing piece to effectively extrude the diaphragm, so that the diaphragm is in sealed abutting connection with the annular valve seat, and the sealing effect between the diaphragm and the annular valve seat is guaranteed.

Description

Technical Field

[0001] The utility model relates to the technical field of valve bodies, and particularly relates to a pneumatic diaphragm valve. Background Technique

[0002] A modular gas supply system (IGS) is a device used for gas control in the semiconductor industry. As semiconductor manufacturing processes become more and more advanced, the requirements for gas control equipment are also getting higher and higher. The modular gas supply system forms at least one pipeline on a substrate by combining a flow path block and a fluid controller, etc. (like building blocks), and conducts modular design. While reducing the volume of the equipment, the installation and maintenance become simpler instead.

[0003] For example, existing fluid control devices / systems include at least one pipeline, and each pipeline includes several fluid controllers and flow blocks. Among them, the fluid controller can be a pneumatic diaphragm valve, a manual diaphragm valve, etc. The valve is mainly used to control the on / off of process gas in the pipeline.

[0004] The above-mentioned pneumatic diaphragm valve includes a valve body and a pneumatic actuating assembly located on the valve body. The valve body has a fluid inlet passage, a fluid outlet passage, and a recess opening upward. Both the fluid inlet passage and the fluid outlet passage can communicate with the recess. The pneumatic diaphragm valve further includes an annular valve seat disposed on the inner bottom surface of the recess and located on the outer periphery of the fluid inlet passage, and an elastically deformable metal diaphragm covering the recess. The pneumatic actuating assembly includes a piston rod that can move up and down and a diaphragm pressing member. By moving the piston rod up and down, the bottom end of the piston rod abuts against the diaphragm pressing member, and the diaphragm pressing member presses or leaves the diaphragm, so that the diaphragm seals or unseals with the annular valve seat. Specifically: when the piston rod of the pneumatic actuating assembly moves towards the annular valve seat, the diaphragm pressing member squeezes and seals the diaphragm onto the annular valve seat, becoming a closed valve state, and the fluid inlet passage is closed and cannot communicate with the fluid outlet passage; when the piston rod of the pneumatic actuating assembly moves away from the annular valve seat, the diaphragm resumes its original state and separates from the annular valve seat to become an open valve state, then the fluid inlet passage and the fluid outlet passage communicate through the recess.

[0005] The metal diaphragm requires a large force to deform and contact the annular valve seat for sealing. Thus, the piston rod moves up and down under the action of the gas driving component in the pneumatic actuating component, applying a large force to the diaphragm pressing member, which in turn causes the diaphragm pressing member to contact and squeeze the diaphragm. Since both the piston rod and the diaphragm pressing member are made of metal, for example, during the switching process of a normally closed valve from the open valve state to the closed valve state, when the driving gas is quickly removed, the piston rod will suddenly apply a large downward force to the diaphragm pressing member, causing excessive impact between the two. Or, for example, during the switching process of a normally open valve from the closed valve state to the open valve state, after quickly removing the driving gas and removing the downward force of the piston rod on the diaphragm pressing member, the diaphragm rebounds and applies a large upward force to the diaphragm pressing member, causing the diaphragm pressing member to impact the piston rod. In both of the above situations, wear will occur between the piston rod and the diaphragm pressing member. In short, in a pneumatic valve that uses a pneumatic actuating component to drive the up and down movement of the piston rod and the diaphragm pressing member to separate or abut the diaphragm and the annular valve seat to open and close the valve, there will be a problem of impact wear between components, which will further affect the effective long-term sealing between the diaphragm and the annular valve seat. Summary of the Invention

[0006] Aiming at the deficiencies of the prior art, the purpose of the present invention is to provide a pneumatic diaphragm valve, which solves the problem that the existing piston rod is prone to cause impact wear between the piston rod and the diaphragm pressing member.

[0007] In order to achieve the above purpose, the present invention adopts the following technical solutions:

[0008] A pneumatic diaphragm valve, which includes:

[0009] A valve body, including a first fluid passage and a second fluid passage;

[0010] An annular valve seat, which is hermetically arranged on the valve body and is located on the outer peripheral side of the top end of the first fluid passage, and the first fluid passage and the second fluid passage are communicated through the annular valve seat;

[0011] A diaphragm, which is elastically deformable, is arranged above the annular valve seat, and the outer edge of the diaphragm is hermetically fixed to the valve body; it further includes:

[0012] A pneumatic actuating component, including a cylinder housing connected to the top end of the valve body, a piston rod arranged in the cylinder housing, a spring elastically pressing against the piston rod, and a diaphragm pressing member axially movably arranged above the diaphragm. The piston rod is axially movably located above the diaphragm pressing member. By introducing and exhausting gas, the piston rod is made to approach or move away from the diaphragm pressing member, so that the diaphragm abuts against or separates from the annular valve seat to close or open the diaphragm valve;

[0013] A buffer member is provided between the piston rod and the diaphragm pressing member, and the piston rod can axially move to abut the buffer member against the diaphragm pressing member.

[0014] In the pneumatic diaphragm valve of the present utility model, regardless of whether the pneumatic diaphragm valve is a normally open valve or a normally closed valve, a buffer member is provided between the piston rod and the diaphragm pressing member. The buffer member refers to a structure that provides impact protection and vibration protection, reduces the impact and vibration external forces transmitted to the components, and can prevent the piston rod and the diaphragm pressing member from coming into contact and colliding with each other. It can be a buffer structure made of a buffer material, or a structure that realizes the buffer function through the deformation or displacement of the buffer member itself. During the process of opening and closing the valve, when the piston rod and the diaphragm pressing member approach each other under the action of gas, spring force, and diaphragm elasticity, the two will not come into direct contact, but will be indirectly contacted and abutted through the buffer member, which not only avoids the direct hard collision between the piston rod and the diaphragm pressing member, but also the piston rod and the diaphragm pressing member will not or rarely wear. Therefore, when the piston rod moves a preset distance, it can drive the diaphragm pressing member to effectively press the diaphragm, and then make the diaphragm seal and abut against the annular valve seat, ensuring the sealing effect between the diaphragm and the annular valve seat. Especially during the process of switching back from the open state to the original closed state in a normally closed valve, it can also avoid the violent impact between the downward movement of the piston rod and the diaphragm pressing member after suddenly removing the gas. The buffer member itself can absorb excessive impact force without affecting the pressing stroke of the diaphragm pressing member, and avoid the series of impacts of the piston rod on the diaphragm pressing member, the diaphragm, and the annular valve seat.

[0015] Preferably, the piston rod includes a rod body and a piston formed on the rod body. The piston is slidably and sealingly connected to the cylinder housing. One side of the piston abuts against the spring, and a driving air chamber is provided on the other side. A gas flow passage communicating with the driving air chamber is formed on the rod body. A first groove is formed at one end of the rod body facing the diaphragm pressing member, and the buffer member protrudes from the first groove.

[0016] With such a setting, the spring and the driving air chamber are respectively located on the two axial sides of the piston. By the relative position relationship between the spring and the driving air chamber, the diaphragm valve can be configured as a normally closed valve or a normally open valve. For example, if the spring abuts against the upper surface of the piston, the driving air chamber is located on one side of the lower surface of the piston and is configured as a normally closed valve. Or, if the spring abuts against the lower surface of the piston, the driving air chamber is located on one side of the upper surface of the piston and is configured as a normally open valve. Thus, the acting force direction of the spring on the piston is opposite to the acting force direction of the gas in the driving air chamber on the piston. The introduced gas enters the driving air chamber through the gas flow passage, thereby controlling the axial movement direction of the piston and the rod body to open the normally closed valve or close the normally open valve. Based on this, a first groove is formed at one end of the rod body facing the diaphragm pressing member, and the buffer member protrudes into the first groove. When the rod body and the diaphragm pressing member approach each other, the buffer member first contacts and collides with the diaphragm pressing member. And because the buffer member is arranged in the groove and is more tightly connected to the rod body, it prevents the buffer member from moving radially and avoids the buffer member from skewing and shifting when colliding with the diaphragm pressing member.

[0017] Preferably, the buffer member includes a mounting portion and a contact portion fixed to the mounting portion. The mounting portion is inserted into the first groove, and the contact portion is located outside the opening of the first groove.

[0018] With such a setting, the mounting portion is used to insert the buffer member on the rod body, which plays a role in axial and radial position limiting. The contact portion is used to contact and buffer the diaphragm pressing member. It is arranged outside the opening of the first groove, and there is a certain distance in the axial direction between its contact surface with the diaphragm pressing member and the end surface of the rod body. This part of the contact portion serves as a buffer layer isolating the rod body and the diaphragm pressing member, avoiding direct contact between the rod body and the diaphragm pressing member. The buffer member with the above structure is convenient for processing and is also convenient for assembling the buffer member with the rod body.

[0019] Preferably, the contact portion has a first contact surface for contacting the diaphragm pressing member, and the radial width of the first contact surface is greater than the radial width of the opening of the first groove, that is, the first contact surface covers the end surface of the rod body outside the periphery of the opening of the first groove, further reducing the possibility of direct contact between the rod body and the diaphragm pressing member.

[0020] Preferably, a chamfer is provided at the opening edge of the first groove to reduce the stress on the contact portion by the rod body and avoid damage to the contact portion due to force.

[0021] Preferably, the contact part has a second contact surface for contacting the rod body. The ratio of the radial width of the second contact surface to the radial width of the mounting part is 0.35 - 0.5. The contact area between the rod body and the contact part is relatively large, so as to disperse the extrusion pressure acting on the second contact surface and avoid damaging the contact part. Through the combined action of the above ratio and the chamfer design, it not only ensures that the second contact surface is large enough to reduce the pressure, but also ensures that the opening edge of the first groove does not directly act on the contact part, so that the contact part is not easily crushed during the buffering process.

[0022] Preferably, the contact part has an annular part corresponding to the rod body. The ratio of the radial width of the annular part to the radial width of the mounting part is 0.6 - 0.75. The annular part is the area between the end of the rod body and the diaphragm pressing part when the piston rod and the diaphragm pressing part collide with each other, and it receives the maximum extrusion pressure. Therefore, the radial width of the annular part is controlled within the above ratio range, so as to ensure that there is a wide enough annular part between the rod body and the diaphragm pressing part. The annular part itself has strong structural strength, and with the chamfer provided at the junction of the annular part and the mounting part, it can avoid stress concentration and prevent the annular part and the mounting part from breaking at the junction, so as to ensure that the annular part is not damaged during the extrusion process.

[0023] Preferably, the surface of the contact part facing the rod body is in limiting abutment with the bottom end surface of the rod body to axially limit the buffer. There is a gap between the surface of the mounting part facing the rod body and the inner bottom surface of the first groove. Its function is that when the buffer collides with the diaphragm pressing part, the contact part of the buffer is compressed and slightly deformed, and moves towards the bottom surface of the first groove. The gap between the mounting part and the bottom surface of the first groove serves as the space for the mounting part to continue moving. Compared with the mounting part directly abutting against the bottom surface of the first groove, the gap can play a certain buffering role.

[0024] Preferably, a second groove is formed on the top surface of the diaphragm pressing part, and the buffer can extend into the second groove and abut against the inner bottom surface of the second groove.

[0025] With such a setting, the function of the second groove is as follows: on the one hand, the buffer moves up and down in the second groove following the rod body, and the second groove can also play a role in radially limiting the buffer to prevent the buffer from skewing with the rod body during the collision; on the other hand, by setting the second groove, the axial length of the entire pneumatic diaphragm valve can be further shortened, making the structure of the pneumatic diaphragm valve more compact.

[0026] Preferably, a reference plane is preset at the bottom end of the cylinder housing. The maximum protruding length of the bottom surface of the buffer member protruding downward relative to the reference plane is H. The diaphragm pressing member has a pressure-receiving surface facing the buffer member and capable of abutting against the buffer member. When the diaphragm is in the fully open state, the distance from the pressure-receiving surface to the reference plane is h, and the sealing stroke of the diaphragm is L, satisfying the following condition: H - h > L.

[0027] With such a setting, taking the normally closed state as an example, the maximum protruding length of the bottom surface of the buffer member protruding downward relative to the reference plane means that in the state where structures such as the diaphragm pressing member and the valve body are not provided, when the piston rod protrudes downward to the limit under the action of pneumatic or spring force relative to the reference plane, the distance from the bottom surface of the buffer member to the reference plane; and H - h represents the maximum axial movement distance of the diaphragm pressing member under the action of the piston rod and the buffer member. H - h > L means that the maximum protruding length of the piston rod has a surplus amount. These surplus amounts can be partly used to set the buffer gap between the buffer member and the diaphragm pressing member, and can also partly be used to make up for the machining errors of the buffer member, the rod body, and the diaphragm pressing member; in addition, due to the collision deformation of the buffer member during long-term use, its axial length will become shorter. Therefore, it is necessary to limit the axial movement stroke of the piston rod to prevent the piston rod from being unable to push the diaphragm pressing member to a position where the diaphragm is tightly sealed against the annular valve seat after the axial length of the buffer member is shortened, which affects the sealing performance between the diaphragm and the annular valve seat. These surplus amounts can also ensure that after the buffer member is deformed and shortened due to long-term buffering, the piston rod can still squeeze the diaphragm pressing member downward to firmly press the diaphragm against the annular valve seat.

[0028] Preferably, the surface of the diaphragm pressing member facing the diaphragm is a curved surface, which protrudes in the direction facing the diaphragm. A thinning groove is provided in the central area of the curved surface. The thinning groove enables the diaphragm pressing member to avoid the central area of the diaphragm when pressing the diaphragm, preventing the directly point contact between the protruding central area of the diaphragm pressing member and the protruding central area of the diaphragm, which may cause excessive pressure. Therefore, setting the thinning groove can avoid damaging the central area of the diaphragm.

[0029] Preferably, the top end of the valve body has a recess, and both the annular valve seat and the diaphragm are located in the recess. The first fluid passage and the second fluid passage are respectively communicated with the recess. With such a setting, the annular valve seat and the diaphragm are accommodated in the recess, making the overall structure more compact.

[0030] Preferably, the piston rod includes a first piston rod and a second piston rod which are separately arranged. The first piston rod is located above the second piston rod, and the bottom end of the second piston rod and the diaphragm pressing member clamp the buffer member.

[0031] With such a setting, when the pneumatic diaphragm valve of the present utility model adopts a double-piston driving mode, the second piston rod located below contacts and collides with the diaphragm pressing member through a buffer member, avoiding direct contact between the second piston rod and the diaphragm pressing member, which may cause unnecessary wear and affect the sealing performance between the diaphragm and the annular valve seat.

[0032] Preferably, the buffer member is made of plastic material, which has good buffering performance, can deform appropriately to reduce the impact force, and does not affect the strokes of the piston rod and the diaphragm pressing member; both the piston rod and the diaphragm pressing member are made of metal material; they have high mechanical strength and long service life.

[0033] Preferably, the diaphragm is made of metal material to provide sufficient strength and elastic deformation ability, and the annular valve seat is made of plastic material to deform to form a good sealing connection when being squeezed by the diaphragm.

[0034] Preferably, the cylinder housing includes a cylinder body and a support seat threadedly connected to the inner bottom end of the cylinder housing. The support seat is threadedly connected to the top end of the valve body through a connecting seat to connect the pneumatic actuator assembly and the valve body into one body, so that the piston rod and the valve body are coaxially arranged, and the piston rod and the diaphragm pressing member are aligned with the central area of the diaphragm, so that the central area of the diaphragm is aligned and sealed with the annular valve seat under the action of the pneumatic actuator assembly; an annular pressing engagement member is provided in the recess, the pressing engagement member supports the connecting seat and seals and presses the outer edge of the diaphragm, and the diaphragm pressing member is located inside the pressing engagement member; the function of the pressing engagement member is, on the one hand, to seal the outer edge of the diaphragm to prevent the gas flowing between the first fluid passage and the second fluid passage from leaking from the outer edge of the diaphragm; on the other hand, to play a role of radial limit on the diaphragm pressing member to prevent the diaphragm pressing member from skewing when being acted on by the piston rod and the buffer member and being unable to align with the central area of the diaphragm, affecting the normal deformation stroke of the diaphragm and resulting in the diaphragm being unable to be in sealing contact with the annular valve seat.

[0035] In summary, compared with the prior art, the present utility model at least has the following beneficial effects:

[0036] In the pneumatic diaphragm valve of the present utility model, a buffer member is provided between the piston rod and the diaphragm pressing member. During the process of opening and closing the valve, when the piston rod and the diaphragm pressing member approach each other under the action of gas, spring force, and diaphragm elasticity, the two do not come into direct contact, but contact and abut through the buffer member. This not only avoids hard collision between the piston rod and the diaphragm pressing member, and the piston rod and the diaphragm pressing member will not or rarely wear. Therefore, when the piston rod moves a preset distance, it can drive the diaphragm pressing member to effectively extrude the diaphragm, and then make the diaphragm seal and abut against the annular valve seat, ensuring the sealing effect between the diaphragm and the annular valve seat. It can also avoid the violent impact between the piston rod and the diaphragm pressing member after suddenly removing the gas. The buffer member itself can absorb excessive impact force without affecting the pressing stroke of the diaphragm pressing member, and avoid the chain impact of the piston rod on the diaphragm pressing member, the diaphragm, and the annular valve seat. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] In order to more clearly illustrate the specific embodiments of the present utility model or the technical solutions in the prior art, the following will briefly introduce the drawings required for use in the description of the specific embodiments or the prior art. Obviously, the drawings in the following description are some embodiments of the present utility model. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained based on these drawings.

[0038] Figure 1 It is a schematic cross-sectional view of the pneumatic diaphragm valve according to an embodiment of the present utility model, wherein the pneumatic diaphragm valve is in a fully open state.

[0039] Figure 2 It is a schematic cross-sectional view of the pneumatic diaphragm valve according to an embodiment of the present utility model from another angle, wherein the pneumatic diaphragm valve is in a closed state.

[0040] Figure 3 is Figure 2 the enlarged view of part A in

[0041] Figure 4 It is a schematic structural view of the diaphragm pressing member according to an embodiment of the present utility model.

[0042] Figure 5 is Figure 4 the schematic structural view of the diaphragm pressing member from another angle of

[0043] Figure 6 It is a schematic cross-sectional view of the pneumatic actuating assembly according to an embodiment of the present utility model, which shows the maximum extended length of the piston rod.

[0044] Figure 7 It is a schematic cross-sectional view of the pneumatic diaphragm valve according to another embodiment of the present utility model, which is a double-piston normally-closed valve.

[0045] Figure 8 The sectional view of the pneumatic diaphragm valve according to another embodiment of the present utility model, which is a double-piston normally open valve.

[0046] Description of the reference numerals

[0047] 10. Valve body; 11. First fluid passage; 12. Second fluid passage; 13. Recess; 14. Diaphragm; 15. Annular valve seat;

[0048] 20. Pneumatic actuating assembly; 21. Cylinder housing; 211. Cylinder body; 212. Support seat; 22. Piston rod; 221. Rod body; 222. Piston; 223. First groove; 224. Driving air chamber; 225. Gas flow passage; 23. Spring; 24. Diaphragm pressing member; 241. Second groove; 242. Thinning groove; 25. Buffer member; 251. Mounting portion; 252. Contact portion; 253. First contact surface; 254. Gap; 255. Second contact surface; 256. Annular portion;

[0049] 30. Pressing engagement member;

[0050] 40. Connecting seat. Detailed implementation manners

[0051] Next, the technical solutions of the present utility model will be clearly and completely described in conjunction with the accompanying drawings. Obviously, the described embodiments are some, but not all, of the embodiments of the present utility model. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present utility model without making creative efforts shall fall within the protection scope of the present utility model.

[0052] In the description of the present utility model, it should be noted that the orientation or positional relationship indicated by the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer", etc. is based on the orientation or positional relationship shown in the accompanying drawings, and is only for the convenience of describing the present utility model and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of the present utility model. In addition, the terms "first", "second", and "third" are only used for descriptive purposes and cannot be construed as indicating or implying relative importance.

[0053] In the description of the present utility model, it should be noted that unless otherwise clearly specified and defined, the terms "installation", "connection", and "coupling" should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be directly connected or indirectly connected through an intermediate medium, and it can be the communication inside two components. For those of ordinary skill in the art, the specific meanings of the above terms in the present utility model can be understood according to specific circumstances.

[0054] Reference appendix Figure 1-8 , such as Figure 1 and Figure 2 As shown, the pneumatic diaphragm valve includes a valve body 10, an annular valve seat 15, a diaphragm 14, and a pneumatic actuation assembly 20. The valve body 10 includes a first fluid passage 11 and a second fluid passage 12. The top of the valve body 10 has a recess 13. The first fluid passage 11 and the second fluid passage 12 are respectively in communication with the recess 13. The annular valve seat 15 is provided on the valve body 10, specifically in the recess 13 and surrounding the outer peripheral side of the top of the first fluid passage 11; in some other embodiments, the top of the valve body 10 may not have a recess 13, and the annular valve seat 15 is directly sealed and fixed on the top surface of the valve body 10, and then the diaphragm 14 is installed and the first fluid passage 11 and the second fluid passage 12 are communicated through other connectable means. In this embodiment, the first fluid passage 11 is a fluid inflow passage, and the second fluid passage 12 is a fluid outflow passage, where the fluid is a process gas in a semiconductor manufacturing process.

[0055] The diaphragm 14 of this embodiment can be elastically deformed, is arranged in the recess 13 and above the annular valve seat 15, and the pneumatic actuation assembly 20 is connected to the top of the valve body 10 and also above the diaphragm 14, and its function is to drive the diaphragm 14 to abut against or separate from the annular valve seat 15 to block or open the diaphragm valve. Specifically, the pneumatic actuation assembly 20 includes a cylinder housing 21 connected to the top of the valve body 10, a piston rod 22 arranged in the cylinder housing 21, a spring 23 elastically pressing against the piston rod 22, and a diaphragm pressing member 24 movably arranged axially above the diaphragm 14. The piston rod 22 is movably arranged axially above the diaphragm pressing member 24. By introducing and exhausting air, the piston rod 22 is made to approach or move away from the diaphragm pressing member 24, so that the diaphragm 14 abuts against or separates from the annular valve seat 15 to close or open the diaphragm valve. In this embodiment, both the piston rod 22 and the diaphragm pressing member 24 are made of a metal material, with high mechanical strength and long service life; the diaphragm 14 is also made of a metal material, such as made of a nickel-cobalt alloy or stainless steel, providing sufficient strength and the ability of elastic deformation and recovery.

[0056] As shown in appendix Figure 1 and appendix Figure 2As shown, the pneumatic diaphragm valve of the present invention can be a single piston normally closed valve, that is, the spring 23 is arranged on the side of the single piston rod 22 away from the diaphragm 14. Figure 2 When the driving gas is not passed, the spring 23 pushes the piston rod 22 and the diaphragm pressing member 24 toward the diaphragm 14 due to the compressed rebound force, so that the diaphragm pressing member 24 abuts against the diaphragm 14, the diaphragm 14 deforms and seals against the annular valve seat 15, the first fluid channel 11 and the second fluid channel 12 are disconnected, and the diaphragm valve is in a closed state. Figure 1 After the driving gas is introduced, the driving gas is generally an inert gas. The upward force of the driving gas on the piston rod 22 is greater than the downward force of the spring 23 on the piston rod 22. The piston rod 22 moves axially upward to move away from the diaphragm 14. The piston rod 22 removes the squeezing effect on the diaphragm pressing piece 24. The diaphragm 14 recovers under the action of its own restoring force and the process gas force between the first fluid channel 11 and the second fluid channel 12, and the diaphragm pressing piece 24 is lifted. The diaphragm valve is in an open state.

[0057] However, during the valve opening process, the diaphragm pressing piece 24 is lifted up at a relatively fast speed and may hit the end of the piston rod 22, causing certain wear. Or when the valve needs to be closed again, the driving gas is suddenly removed, and the piston rod 22 suddenly moves downward under the action of the spring 23, close to the diaphragm pressing piece 24. The force of the spring 23 is relatively large, causing the end of the piston rod 22 to suddenly hit the diaphragm pressing piece 24, which may cause excessive impact force on the annular valve seat 15 and affect the sealing. In order to ensure the mechanical strength of the diaphragm pressing piece 24 and the piston rod 22, both are generally made of metal. Therefore, during the frequent opening and closing of the valve, the two frequently collide, which can easily cause unnecessary blockage and wear on the opposing surfaces of the two. Even if the wear of the two is small, the impact force is large, which in turn affects the sealing of the diaphragm pressing piece 24 on the diaphragm 14 and the annular valve seat 15.

[0058] by Figure 1 and Figure 2Taking the normally closed pneumatic diaphragm valve as an example, since there is a gas flow passage 225 on the piston rod 22, after the driving gas is introduced into the gas flow passage 225, the driving gas acts on the lower surface of the piston rod 22, overcoming the elastic force of the spring 23 to make the piston rod 22 rise. In order to ensure good sealing effect between the diaphragm 14 and the annular valve seat 15 in the normally closed state, that is, the diaphragm pressing member 24 presses against the diaphragm 14 to prevent the process gas from being conducted in the normally closed state. Therefore, the elastic force of the spring 23 is set to be relatively large, and the resilience of the spring 23 after being compressed and installed is large enough, about 200N, to be able to press tightly the diaphragm pressing member 24 and the annular valve seat 15. Therefore, when opening the normally closed valve, the driving gas has to overcome a force of about 200N to make the piston rod 22 move upward to open the valve; and after the piston rod 22 rises, the diaphragm 14 is restored and pushes up the diaphragm pressing member 24 under the action of its own restoring force and the process gas acting force between the first fluid passage 11 and the second fluid passage 12. The lifting speed of the diaphragm pressing member 24 is relatively fast and it is easy to hit the end of the piston rod 22. When removing the driving gas to close the normally closed diaphragm valve again, the piston rod 22 suddenly moves downward under the action of the force of about 200N of the spring 23, and its end will also hit the diaphragm pressing member 24; after multiple impacts, not only unnecessary blockage and wear will occur on the opposite surfaces of the diaphragm pressing member 24 and the piston rod 22, but the initial distance between the opposite surfaces becomes larger, resulting in that the piston rod 22 cannot press tightly the diaphragm pressing member 24 according to the established pushing stroke, the diaphragm pressing member 24 cannot make the diaphragm 14 deform to be in complete sealing contact with the annular valve seat 15, and moreover, the impact force between the two is very large, causing excessive deformation of the plastic annular valve seat 15, and the sealing effect between the diaphragm 14 and the annular valve seat 15 is weakened, and the pneumatic diaphragm valve cannot maintain the closed state.

[0059] Therefore, a buffer member 25 is provided between the piston rod 22 and the diaphragm pressing member 24 in this embodiment, and the piston rod 22 can axially move to abut the buffer member 25 against the diaphragm pressing member 24. The function of the buffer member 25 is, on the one hand, to prevent the piston rod 22 and the diaphragm pressing member 24 from directly contacting, so that the piston rod 22 and the diaphragm pressing member 24 will not or rarely wear. The piston rod 22 moves a preset distance to drive the diaphragm pressing member 24 to effectively squeeze the diaphragm 14, so as to make the diaphragm 14 in sealing contact with the annular valve seat 15, ensuring the sealing effect between the diaphragm 14 and the annular valve seat 15; on the other hand, it can absorb excessive impact force without affecting the pressing stroke of the diaphragm pressing member 24, and prevent the piston rod 22 from causing a series of impacts on the diaphragm pressing member 24, the diaphragm 14 and the annular valve seat 15. Among them, the buffer member 25 can be a structure made of buffer material, or other structures that are slightly deformed under force to buffer the piston rod 22 and the diaphragm pressing member 24, or structures that change the stroke to achieve the buffer function, or other buffer structures suitable for being clamped between the piston rod 22 and the diaphragm pressing member 24. For example, the buffer member 25 can be a plastic part or a damping spring, etc.

[0060] As shown in the attached Figure 1 embodiment, a normally closed pneumatic diaphragm valve; the piston rod 22 includes a rod body 221 and a piston 222 formed on the rod body 221. The piston 222 is formed on the outer periphery of the rod body 221 and is slidably and sealingly connected to the inner wall of the cylinder housing 21. A gas flow passage 225 communicating with the driving air chamber 224 is formed on the rod body 221. The spring 23 abuts against the upper surface of the piston 222. A driving air chamber 224 is provided on the lower surface of the piston 222. Here, it can either refer to forming the driving air chamber 224 by opening a groove on the lower surface of the piston 222 or refer to the space on one side (lower side) of the lower surface of the piston 222 to form the driving air chamber 224. The driving air chamber 224 is communicated with the gas flow passage 225, and driving gas can be introduced to apply an axially upward acting force to the lower surface of the piston 222; the rod body 221 and the piston 222 are fixedly connected. One end of the rod body 221 facing the diaphragm pressing member 24 is provided with a first groove 223, and the buffer member 25 protrudes into the first groove 223; when the rod body 221 and the diaphragm pressing member 24 approach each other, the buffer member 25 first contacts and collides with the diaphragm pressing member 24 to absorb the impact force. Since the buffer member 25 is arranged in the first groove 223, it is more tightly connected to the rod body 221, preventing the buffer member 25 from moving radially and avoiding the buffer member 25 from skewing and shifting when colliding with the diaphragm pressing member 24.

[0061] In other embodiments, as shown in the attached Figure 8 figure, the pneumatic diaphragm valve is a normally open valve. The structures of the rod body 221 and the piston 222 remain unchanged. The spring 23 abuts against the lower surface of the piston 222. The driving air chamber 224 is communicated with the upper surface of the piston 222 and is also communicated with the gas flow passage 225. Driving gas can be introduced to apply an axially downward acting force to the upper surface of the piston 222. The connection of the buffer member 25 to the rod body 221 has the same effect and will not be elaborated here. In addition, the setting or formation of the driving air chamber 224 in the normally open valve refers to the above-mentioned normally closed valve.

[0062] In this embodiment, as shown in the attached Figure 1 figure, there is only one piston rod 22 provided, the number of pistons 222 on the rod body 221 is one, and correspondingly there is one gas flow passage 225. And in other embodiments, as shown in the attached Figure 7 and the attached Figure 8As shown in the figure, the piston rod includes a first piston rod and a second piston rod which are separately arranged. The first piston rod is located above the second piston rod. The first piston rod and the second piston rod may respectively include a rod body 221 and a piston 222, which is a double-piston structure. A driving air chamber 224 is correspondingly provided on one side of each piston 222, and the gas flow channel 225 is communicated with each driving air chamber 224. The setting method of the spring can refer to the above-mentioned embodiment. Based on the double-piston structure, the force of the gas on the piston is greater, and the piston responds more promptly. However, the impact force on the diaphragm pressing member is also greater. Therefore, it is more necessary to provide a buffer member. The bottom end of the second piston rod and the diaphragm pressing member 24 clamp the buffer member 25. The buffer member can be fixedly connected to the bottom end of the second piston rod. The specific connection method can refer to the above-mentioned embodiment. The second piston rod located below contacts and collides with the diaphragm pressing member 24 through the buffer member 25, avoiding the direct contact between the second piston rod and the diaphragm pressing member 24, which may cause unnecessary wear and affect the sealing performance between the diaphragm 14 and the annular valve seat 15.

[0063] In addition, in addition to the setting method of this embodiment, the buffer member 25 can also be inserted into a groove formed in the diaphragm pressing member 24. In addition, there are various setting methods for the buffer member 25. For example, the buffer member 25 is fixed to the end surface of the rod body 221 facing the diaphragm pressing member 24 by welding or bonding. Or, the buffer member 25 is a coating structure made of a buffer material and is attached to the end surface of the rod body 221 facing the diaphragm pressing member 24.

[0064] As shown in the attached Figure 3 figure, the buffer member 25 includes a mounting portion 251 and a contact portion 252 fixed to the mounting portion 251, and has a relatively large axial length, and can buffer the impact force through appropriate compression deformation. Specifically, as shown in the attached Figure 3 figure, the mounting portion 251 is inserted into the first groove 223. The first groove 223 plays a role of axial and radial limiting for the buffer member 25. The contact portion 252 is located outside the opening of the first groove 223. The first contact surface 253 for contacting and buffering with the diaphragm pressing member 24 and the end surface of the rod body 221 have a certain distance in the axial direction. This part of the contact portion 252 serves as a buffer layer and can absorb part of the impact force. The buffer member 25 of this embodiment is convenient for processing and is also convenient for the assembly of the buffer member 25 and the rod body 221. The mounting portion 251 can be in interference fit with the first groove 223, ensuring the stable connection between the buffer member 25 and the rod portion.

[0065] Furthermore, the radial width of the first contact surface 253 is greater than the radial width of the opening of the first groove 223. The advantages are as follows. On the one hand, the first contact surface 253 covers the end face of the rod body 221 outside the opening of the first groove 223, further reducing the possibility of direct contact between the rod body 221 and the diaphragm pressing member 24. On the other hand, when the buffer member 25 is subjected to a large impact, due to the relatively wide first contact surface 253, the pressure received by the buffer member 25 is small, and even if some deformation occurs, the buffer member 25 as a whole will not be squeezed into the first groove 223, and the position of the buffer member 25 on the rod body 221 will not change greatly, ensuring the effective extrusion stroke of the piston rod 22. The radial width of the first contact surface 253 can be equal to the radial width of the rod body 221 or greater than the radial width of the rod body 221. In this embodiment, as shown in the appendix Figure 3 As shown, the radial width of the first contact surface 253 can be equal to the radial width of the rod body 221.

[0066] As shown in the appendix Figure 3 As shown, a chamfer is provided at the opening edge of the first groove 223. The chamfer can be an inclined chamfer or a rounded corner. In this embodiment, that is, the inner edge at the bottom end of the rod body 221 has a rounded corner to reduce the stress of the rod body 221 on the contact portion 252 and avoid damage to the contact portion 252 due to force. The contact portion 252 has a second contact surface 255 for contacting the rod body 221, and the contact portion 252 has an annular portion 256 corresponding to the rod body 221. Therefore, the radial width of the second contact surface 255 is smaller than the radial width of the annular portion 256 of the contact portion 252, defined as b1, the radial width of the mounting portion is defined as b2, and the radial width of the annular portion 256 is defined as b3.

[0067] In some embodiments, b1 is the area outside the opening chamfer of the first groove 223. Design b1 and b2 such that b1:b2 = 0.35 - 0.5, preferably b1:b2 = 0.43. Together with the design of the chamfer, while ensuring a certain strength of the buffer member 25, b1 is increased. Under the same pressure, the pressure of the rod body 221 on the annular portion 256 is reduced, thereby avoiding the annular portion 256 being crushed and damaged during the buffer extrusion process.

[0068] In other embodiments, design b3 and b2 such that b3:b2 = 0.6 - 0.75, preferably b3:b2 = 0.66. Together with a chamfer (not shown) provided at the junction of the annular portion 256 and the mounting portion 251, stress concentration is avoided, and the annular portion 256 and the mounting portion 251 are prevented from breaking at the junction. At the same time, the structural strength of the annular portion 256 itself is relatively strong, and the annular portion 256 can be prevented from being crushed and damaged during the buffer extrusion process.

[0069] In this embodiment, the buffer member 25 is made of plastic material, which can be PCTFE, PFA or PTFE. It has good buffering performance, can deform appropriately to reduce the impact force, and basically does not affect the strokes of the piston rod 22 and the diaphragm pressing member 24.

[0070] As shown in the attached Figure 1 figure, the surface of the contact portion 252 facing the rod body 221 is in limiting abutment with the bottom end surface of the rod body 221 to axially limit the buffer member 25. There is a gap 254 between the surface of the mounting portion 251 facing the rod body 221 and the surface of the first groove 223. In other words, there is a gap 254 located in the first groove 223 between the mounting portion 251 and the rod body 221. Its function is that when the buffer member 25 collides with the diaphragm pressing member 24, the contact portion 252 of the buffer member 25 is pressed to generate slight deformation and moves towards the bottom surface of the first groove 223. The gap 254 between the mounting portion 251 and the bottom surface of the first groove 223 serves as the space for the mounting portion 251 to continue moving. Compared with the mounting portion 251 directly abutting against the bottom surface of the first groove 223, the gap 254 can play a certain buffering role. Of course, in other embodiments with smaller impact forces, the surface of the mounting portion 251 facing the rod body 221 can be in abutment with the bottom surface of the first groove 223.

[0071] As shown in the attached Figure 1 、 2 、Figure 4, a second groove 241 is formed on the top surface of the diaphragm pressing member 24. The inner diameter of the second groove 241 is larger than the outer diameters of the buffer member 25 and the rod body 221, so that the buffer member 25 and the rod body 221 can axially move in the second groove 241. The buffer member 25 can extend into the second groove 241 and abut against the inner bottom surface of the second groove 241, thereby pushing the diaphragm pressing member 24 towards the diaphragm 14. The inner diameter of the second groove 241 should not be too large, because the second groove 241 needs to play a role in radially limiting the buffer member 25 to prevent the buffer member 25 and the rod body 221 from skewing during collision. In addition, if a structure such as the buffer member 25 being clamped between two planes or between a groove and a plane is adopted, due to the cumulative machining errors of multiple parts, the axial movement strokes of the piston rod 22 and the diaphragm pressing member 24 deviate from the preset values. Therefore, in this embodiment, the first groove 223, the buffer member 25 and the second groove 241 are cooperated with each other, which can avoid the cumulative manufacturing errors of the internal parts, make the axial movement strokes of the piston rod 22 and the diaphragm pressing member 24 more accurately controllable, and further ensure that the upper surface of the diaphragm is almost not stressed and in a fully open state when the pneumatic diaphragm valve is in the open valve state. Moreover, by providing the second groove 241, the axial length of the entire pneumatic diaphragm valve can be further shortened, making the structure of the pneumatic diaphragm valve more compact.

[0072] As shown in the attached Figure 1 、 2As shown in FIGS. 5 and 6, a reference plane is preset at the bottom end of the cylinder housing 21. The maximum extension length H of the bottom surface of the buffer member 25 at the bottom end of the piston rod 22 extending downward relative to the reference plane means that: when the structures such as the diaphragm pressing member 24 and the valve body 10 are not provided, the piston rod 22 extends downward to the limit under the action of pneumatic force or the spring 23 relative to the reference plane, and the distance from the bottom surface of the buffer member 25 to the reference plane; the diaphragm pressing member 24 has a pressure-receiving surface facing the buffer member 25 and capable of abutting against the buffer member 25. When the diaphragm 14 is in the fully open state, which means that the upper surface of the diaphragm 14 is basically not stressed, the distance from the pressure-receiving surface to the reference plane is h. Thus, H - h represents the maximum axial movement distance of the diaphragm pressing member 24 under the action of the piston rod 22. The sealing stroke of the diaphragm 14 means that when the pneumatic diaphragm valve is in the fully open state, the distance from the position of the diaphragm 14 corresponding to the diaphragm pressing member 24 to the reference plane is L1. When the pneumatic diaphragm valve is in the closed valve state, the diaphragm 14 is in sealing abutment with the annular valve seat 15, and its position to the reference plane is L2. L = L2 - L1, that is, the deformation length of the position of the diaphragm 14 corresponding to the diaphragm pressing member 24 in the axial direction.

[0073] It should be emphasized that the above parameters satisfy the following conditions: H - h > L, which means that the maximum axial movement stroke of the diaphragm pressing member 24 is greater than the sealing stroke of the diaphragm 14, that is, the maximum extension length of the piston rod 22 can ensure that the diaphragm 14 is in sealing abutment with the annular valve seat 15 and there is a surplus. These surpluses can be partly used to set the buffer gap between the buffer member 25 and the diaphragm pressing member 24, and can also be partly used to compensate for the machining errors of the buffer member 25, the rod body 221, and the diaphragm pressing member 24. At the same time, due to the collision deformation of the buffer member 25 during long-term use, its axial length will become shorter. Therefore, it is necessary to limit the axial movement stroke of the piston rod 22 to avoid that after the axial length of the buffer member 25 is shortened, the piston rod 22 cannot push the diaphragm pressing member 24 to the position where the diaphragm 14 is in sealing abutment with the annular valve seat 15, which affects the sealing performance between the diaphragm 14 and the annular valve seat 15. These surpluses can also ensure that after the buffer member 25 is deformed and shortened due to long-term buffering, the piston rod 22 can still push down the diaphragm pressing member 24 to firmly press the diaphragm 14 against the annular valve seat 15 in a sealed manner.

[0074] Preferably, as Figure 5 shown, the surface of the diaphragm pressing member 24 facing the diaphragm 14 is a curved surface, which protrudes in the direction of the diaphragm 14. A thinning groove 242 is provided in the central area of the curved surface, and the edge of the thinning groove 242 is a rounded corner structure. The thinning groove 242 enables the diaphragm pressing member 24 to avoid the central area of the diaphragm 14 when pressing the diaphragm 14, preventing the direct point contact between the protruding central area of the diaphragm pressing member 24 and the protruding central area of the diaphragm 14, which may cause excessive pressure. Therefore, the setting of the thinning groove 242 can avoid damaging the central area of the diaphragm 14.

[0075] In this embodiment, the cylinder housing 21 includes a cylinder block 211 and a support seat 212 threadedly connected to the inner bottom end of the cylinder housing 21. The support seat 212 is threadedly connected to the top end of the valve body 10 through a connecting seat 40 to connect the pneumatic actuating assembly 20 and the valve body 10 into an integral body, so that the piston rod 22 and the valve body 10 are coaxially arranged, and the piston rod 22 and the diaphragm pressing member 24 are aligned with the central region of the diaphragm 14, so that the central region of the diaphragm 14 is aligned and sealed with the annular valve seat 15 under the action of the pneumatic actuating assembly 20; an annular pressing engagement member 30 is provided in the recess 13, the pressing engagement member 30 supports the connecting seat 40 and tightly presses and seals the outer edge of the diaphragm 14, and the diaphragm pressing member 24 is located inside the pressing engagement member 30; the function of the pressing engagement member 30 is, on the one hand, to seal the outer edge of the diaphragm 14 to prevent the gas flowing between the first fluid passage 11 and the second fluid passage 12 from leaking from the outer edge of the diaphragm 14; on the other hand, to radially limit the diaphragm pressing member 24 to prevent the diaphragm pressing member 24 from tilting when being acted on by the piston rod 22 and the buffer member 25 and being unable to be aligned with the central region of the diaphragm 14, affecting the normal deformation stroke of the diaphragm 14 and resulting in the diaphragm 14 being unable to be in sealing contact with the annular valve seat 15.

[0076] The above embodiments are only the preferred embodiments of the present invention, and the scope of protection of the present invention cannot be limited thereby. Any non-substantial changes and substitutions made by those skilled in the art based on the present invention belong to the scope of protection required by the present invention.

Claims

1. A pneumatic diaphragm valve, comprising: A valve body, including a first fluid passage and a second fluid passage; An annular valve seat, sealingly disposed on the valve body and located on the outer peripheral side of the top end of the first fluid passage, and the first fluid passage and the second fluid passage communicate via the annular valve seat; A diaphragm, which is elastically deformable, disposed above the annular valve seat, and the outer edge of the diaphragm is sealingly fixed to the valve body; characterized in that it further includes: A pneumatic actuating assembly, including a cylinder housing connected to the top end of the valve body, a piston rod disposed in the cylinder housing, a spring elastically pressing against the piston rod, and a diaphragm pressing member axially movably disposed above the diaphragm, the piston rod is axially movably located above the diaphragm pressing member, and by introducing and exhausting air, the piston rod approaches or moves away from the diaphragm pressing member, so that the diaphragm abuts against or separates from the annular valve seat to close or open the diaphragm valve; A buffer member is provided between the piston rod and the diaphragm pressing member, and the piston rod can axially move to abut the buffer member against the diaphragm pressing member.

2. The pneumatic diaphragm valve according to claim 1, characterized in that, The piston rod includes a rod body and a piston formed on the rod body, the piston is slidably and sealingly connected to the cylinder housing, one side of the piston abuts against the spring, and a driving air chamber is provided on the other side, a gas flow passage communicating with the driving air chamber is formed on the rod body, a first groove is formed at one end of the rod body facing the diaphragm pressing member, and the buffer member protrudes into the first groove.

3. The pneumatic diaphragm valve according to claim 2, wherein The buffer member includes a mounting portion and a contact portion fixed to the mounting portion, the mounting portion is inserted into the first groove, and the contact portion is located outside the opening of the first groove.

4. The pneumatic diaphragm valve according to claim 3, wherein The contact portion has a first contact surface for contacting the diaphragm pressing member, and the radial width of the first contact surface is greater than the radial width of the opening of the first groove; Alternatively, a chamfer is provided at the opening edge of the first groove, the contact portion has a second contact surface for contacting the rod body, and the ratio of the radial width of the second contact surface to the radial width of the mounting portion is 0.35 - 0.5; Alternatively, the contact portion has an annular portion corresponding to the rod body, the ratio of the radial width of the annular portion to the radial width of the mounting portion is 0.6 - 0.75, and a chamfer is provided at the junction of the annular portion and the mounting portion.

5. The pneumatic diaphragm valve according to claim 3, characterized in that, The surface of the contact portion facing the rod body is in limiting abutment with the bottom end surface of the rod body, and there is a gap between the surface of the mounting portion facing the rod body and the inner bottom surface of the first groove.

6. The pneumatic diaphragm valve according to claim 1 or 2, characterized in that, A second groove is formed on the top surface of the diaphragm pressing member, and the buffer member can extend into the second groove and abut against the inner bottom surface of the second groove.

7. The pneumatic diaphragm valve according to any one of claims 1 to 3, characterized in that, A reference plane is preset at the bottom end of the cylinder housing, the maximum extension length of the bottom surface of the buffer member extending downward relative to the reference plane is H, the diaphragm pressing member has a pressure-receiving surface facing the buffer member and capable of abutting against the buffer member, when the diaphragm is in the fully open state, the distance from the pressure-receiving surface to the reference plane is h, and the sealing stroke of the diaphragm is L, satisfying the following condition: H - h > L.

8. The pneumatic diaphragm valve according to claim 1, characterized in that, The surface of the diaphragm pressing member facing the diaphragm is a curved surface, which protrudes in the direction facing the diaphragm, and a thinning groove is provided in the central region of the curved surface.

9. The pneumatic diaphragm valve according to claim 1, wherein The top end of the valve body has a recess, the annular valve seat and the diaphragm are both located in the recess, and the first fluid passage and the second fluid passage are respectively communicated with the recess; alternatively, the buffer member is made of plastic material, and the piston rod and the diaphragm pressing member are both made of metal material; Alternatively, the diaphragm is made of metal material, and the annular valve seat is made of plastic material.

10. The pneumatic diaphragm valve according to claim 9, characterized in that, The piston rod includes a first piston rod and a second piston rod which are separately arranged. The first piston rod is located above the second piston rod, and the bottom end of the second piston rod and the diaphragm pressing member clamp the buffer member; Alternatively, the cylinder housing includes a cylinder body and a support seat threadedly connected to the inner bottom end of the cylinder housing. The support seat is threadedly connected to the top end of the valve body through a connecting seat. An annular pressing engagement member is provided in the recess. The pressing engagement member supports the connecting seat and seals and presses the outer edge of the diaphragm, and the diaphragm pressing member is located inside the pressing engagement member.

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