Composite membrane and constant pressure valve with same

Abstract

The utility model relates to the technical field of fluid control equipment, in particular to a composite membrane and a constant pressure valve provided with the composite membrane, the composite membrane comprises a disc-shaped membrane body, the membrane body is provided with a core hole convenient for a valve rod to penetrate through, the membrane body comprises an elastic lining piece, a wrapping piece and a protective layer, the elastic lining piece is of a disc-shaped structure, and the wrapping piece is arranged on the elastic lining piece. The wrapping piece wraps the elastic lining piece, and the protective layer is arranged on the outer surface of the wrapping piece; a positioning boss is arranged on the edge of the wrapping piece; the constant pressure valve comprises an upper valve seat, a lower valve seat, a valve rod and a valve element, a composite membrane is arranged in a valve cavity formed after the upper valve seat and the lower valve seat are covered up and down, and the valve rod penetrates through the composite membrane and then is connected with the valve element. The constant pressure valve solves the abnormal problems that the diaphragm falls off and the supporting fan blades are stuck under high-pressure impact when a traditional constant pressure valve is used, is convenient and fast to disassemble, assemble and maintain, and convenient to store and transport, ensures the sealing performance, improves the use safety and prolongs the service life.

Description

Technical Field

[0001] The utility model relates to the technical field of fluid control equipment, in particular to a composite diaphragm and a constant pressure valve provided with the composite diaphragm. Background Art

[0002] A constant pressure valve is a pilot valve (auxiliary valve) that works with the main valve to achieve specific functions in fluid control. Traditional constant pressure valves generally consist of two valve seats that cover each other downward to form a valve cavity. An elastic deformation component is installed in the valve cavity. The elastic deformation component is usually set at the junction of the two valve seats. The valve core passes through the valve cavity and the elastic deformation component at the same time. The two valve seats are respectively provided with interfaces for air and fluid to enter and exit. The in and out process of one end of the valve core at the opening of one of its valve seats controls the in and out of the fluid. Figure 5 、 Figure 6 The figure shows a common structure of a traditional constant pressure valve, which consists of an upper valve seat 11', a lower valve seat 12', a valve core 20', a valve stem 30' and an elastic deformation component, wherein the upper valve seat 11' and the lower valve seat 12' are fastened together in opposite directions to form a valve cavity, and the valve core 20', the valve stem 30' and the elastic deformation component are located in the valve cavity. The upper valve seat 11' is provided with an air source interface 50', and the lower valve seat 12' is provided with a first fluid interface 601' and a second fluid interface 602' (according to actual needs, the fluid inlet and outlet functions of the interface 601' and the interface 602' are interchangeable. Here, the interface 601' is used as the fluid outlet and the interface 602' is used as the fluid inlet). Figure 4 、 Figure 6 As shown, the elastic deformation component is composed of a support fan 401', an inner fixed ring 402', an outer fixed ring 403', an upper diaphragm 404', and a lower diaphragm 405'. The elastic deformation component divides the valve cavity into an upper cavity and a lower cavity. During operation, the interface 50' of the upper valve seat 11' is connected to the air source, and compressed air is introduced into the upper cavity. When the pressure in the upper cavity is greater than the pressure in the lower cavity, the elastic deformation component is pressed downward, thereby driving the valve core 20' to operate, so that it controls the second fluid interface 602' on the lower valve seat 12', thereby controlling the flow at the fluid inlet. This type of elastic deformation component has a complex structure and is composed of many components. It is not only difficult to disassemble and maintain, but also extremely inconvenient to manage and transport the components. When the constant pressure valve is working, the elastic deformation component is likely to cause gaps between parts during the deformation process, which can cause fluid to penetrate and damage the sealing performance. The penetration of fluid can also easily affect its deformation performance and greatly reduce the control effect of the constant pressure valve. In severe cases, it may cause the diaphragm to fall off from the inner and outer fixing rings that clamp it, affecting the fluid control effect and even causing production problems and resulting in large economic losses. Utility Model Content

[0003] The purpose of the utility model is to provide a composite diaphragm and a constant pressure valve provided with the composite diaphragm to solve the above technical problems.

[0004] The technical problem solved by the present invention can be achieved by adopting the following technical solutions:

[0005] On the one hand, the utility model provides a composite diaphragm, comprising a diaphragm body, the diaphragm body being a disc-shaped structure and having a core hole for facilitating the passage of a valve stem, wherein the diaphragm body comprises an elastic lining member, a wrapping member, and a protective layer, the elastic lining member being a disc-shaped structure, the wrapping member being wrapped around the elastic lining member, and the protective layer being disposed on the outer surface of the wrapping member;

[0006] The edge of the wrapping piece is provided with a positioning boss so that when the diaphragm body is installed in the valve cavity, the installation position can be located by the positioning boss, and after the installation is completed, the edge of the diaphragm body can fit more closely with the inner wall of the valve cavity, thereby improving the sealing and ensuring that the two chambers separated by the diaphragm body are independent of each other.

[0007] The utility model integrates the elastic deformation components in the traditional constant pressure valve into an integrated design and manufacturing by providing a wrapping part and an elastic lining part, thereby improving the safety of the structural parts and increasing the service life of the product.

[0008] Preferably, the elastic lining member is made of stainless steel.

[0009] Preferably, the elastic lining member is provided with a through hole corresponding to the core hole, and the thickness of the elastic lining member gradually decreases outward along the through hole.

[0010] Preferably, the wrapping member is made of nitrile rubber.

[0011] Preferably, positioning bosses are provided on both opposite side surfaces of the edge of the wrapping piece.

[0012] Preferably, the protective layer is made of any one of nitrile rubber (NBR), ethylene propylene diene monomer (EPDM) and polytetrafluoroethylene (PTFE).

[0013] Preferably, the protective layer includes an upper protective layer and a lower protective layer, which are respectively arranged on two opposite sides of the packaging piece.

[0014] Preferably, two opposite surfaces of the packaging piece are each provided with a recessed structure, and a protective layer is provided in any of the recessed structures.

[0015] On the other hand, the utility model provides a constant pressure valve provided with the composite diaphragm, which comprises an upper valve seat, a lower valve seat, a valve stem and a valve core. The upper valve seat and the lower valve seat overlap each other to form a valve cavity, and the valve stem passes through the valve cavity and is connected to the valve core.

[0016] The composite diaphragm is provided in the valve cavity, and the valve stem passes through the composite diaphragm and is connected to the valve core.

[0017] Preferably, another protective layer made of PTFE is provided on the composite diaphragm, which is located on the surface of the composite diaphragm in contact with the lower valve seat.

[0018] Beneficial effects: Due to the adoption of the above technical solution, the present invention solves the abnormal problems of the traditional constant pressure valve such as the diaphragm falling off and the support fan blades getting stuck under high-pressure impact. By adjusting the diaphragm assembly of the traditional multi-component structure into an integrated structure, the disassembly and maintenance of the components are convenient and fast, and the storage and transportation of the product after production are also convenient. In addition, since the integrated structure ensures the sealing performance, the safety and service life of the diaphragm body are improved, and the service life and stability of the constant pressure valve product using the diaphragm are also improved. In summary, the present invention has the following advantages:

[0019] 1) Integrated design, compact structure;

[0020] 2) Equipment maintenance (here refers to the installation and replacement of the diaphragm in the constant pressure valve) is convenient and fast;

[0021] 3) Easy to store, manage and transport;

[0022] 4) Good safety, compared with the traditional multi-component structure, its sealing and durability are better;

[0023] 5) Long service life. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 This is a schematic cross-sectional view of the composite diaphragm of the present invention;

[0025] Figure 2 This is a structural schematic diagram of the composite diaphragm of the present utility model;

[0026] Figure 3 This is a schematic cross-sectional view of the constant pressure valve of the present utility model;

[0027] Figure 4 A structural diagram of the elastic deformation component of a traditional constant pressure valve (the upper diaphragm is hidden);

[0028] Figure 5 This is a structural diagram of a traditional constant pressure valve;

[0029] Figure 6 for Figure 5 A schematic diagram of a cross-sectional structure. DETAILED DESCRIPTION

[0030] In order to make the technical means, creative features, purpose and efficacy of the present invention easy to understand, the present invention is further described below in conjunction with specific illustrations. It should be noted that the terms "first", "second", "third", "fourth" and the like (if any) in the specification and claims of the present invention are used to distinguish similar objects, and are not necessarily used to describe a specific order or sequence. It should be understood that the data used in this way can be interchangeable where appropriate, so that the embodiments described herein can be implemented in an order other than that illustrated or described herein. In addition, the terms "including" or "having" and any variations thereof are intended to cover non-exclusive inclusions, for example, a product or device comprising a series of components or units is not necessarily limited to those components or units clearly listed, but may include other components or components that are not clearly listed or that are inherent to these products or devices.

[0031] Reference Figure 1 、 Figure 2 In some embodiments, the present invention provides a composite diaphragm, including a diaphragm body, which has a disc-shaped structure as a whole (it is not limited to a disc-shaped structure here, and the specific appearance structure can be determined according to the actual valve cavity structure. It only needs to ensure that its sheet structure has a certain elasticity and can be deformed under the action of pressure difference to push the valve stem to move). The diaphragm body has a core hole 4001. The setting of the core hole 4001 facilitates the valve stem to pass through and connect to the valve core, wherein,

[0032] The diaphragm body includes an elastic lining 401, a wrapping member 402 and a protective layer 403.

[0033] The elastic lining member 401 is in a disc-shaped structure, the wrapping member 402 is wrapped around the elastic lining member 401, and the protective layer 403 is provided on the outer surface of the wrapping member 402;

[0034] A positioning boss 404 is provided on the edge of the wrapping member 402 so that when the diaphragm body is installed in the valve cavity of the working valve, the installation position can be located by the positioning boss 404, and after the installation is completed, the edge of the diaphragm body can fit more closely with the inner wall of the valve cavity, thereby improving the sealing and ensuring that the two chambers separated by the diaphragm body are independent.

[0035] It should be noted that the elastic lining of the present invention is configured as an elastic metal product to ensure that it has a good service life while having strong deformation and recovery properties.

[0036] In addition, the elastic lining member of the present invention is set as a sheet structure so that it corresponds to the shape of the diaphragm body, and a corresponding opening is also provided at the position of the core hole thereon (the inner wall of the opening is also covered by the wrapping member). After being installed in the valve cavity of the constant pressure valve, the edge of the diaphragm body (that is, the position of the positioning boss of the wrapping member) fits against the inner wall of the inner cavity of the valve body, thereby dividing the valve cavity into two upper and lower chambers, such as Figure 3 As shown, the valve stem connected to the valve core passes through the core hole, so that the upper part of the valve stem is located in the upper chamber and the lower part of the valve stem is located in the lower chamber. When the valve stem moves, the diaphragm moves. Alternatively, when the diaphragm is deformed by the pressure difference between the upper and lower chambers, it drives the valve stem to move, and then the valve core moves accordingly, thereby controlling the flow rate of fluid in and out by blocking the opening in one of its chambers through the valve core. When the diaphragm body of this utility model is set in a constant pressure valve, its typical application is to pass compressed air into one side chamber separated by the diaphragm, so that a pressure difference is formed between the two chambers, thereby causing the diaphragm to deform, driving the valve stem to move, and then synchronously driving the valve core to move.

[0037] In order to enable the diaphragm body to provide better elastic support for the movement of the valve stem / valve core when the constant pressure valve works, the utility model can be arranged according to the following structure: in some embodiments, the elastic lining member is made of stainless steel.

[0038] In some preferred embodiments, the elastic lining is made of 304 stainless steel in a sheet structure so that it has good elastic properties and a good service life.

[0039] In the application scenarios of the present invention, the inner cavity of the constant pressure valve is generally a cylindrical structure. At this time, the elastic lining is provided as a disc-shaped structure corresponding to the cylindrical valve cavity. After the wrapping member is provided on the outside, the whole is a disc-shaped structure that matches the cylindrical valve cavity. That is to say, after the formed diaphragm body is installed in the valve cavity, its edge fits the inner wall of the valve cavity.

[0040] In order to improve the service life of the structure and reduce or even avoid problems such as damage or leakage at the connection between the valve stem and the composite diaphragm, the utility model can be arranged as follows: In some embodiments,

[0041] The elastic lining member is provided with a through hole corresponding to the core hole, and the thickness of the elastic lining member gradually decreases outward along the through hole.

[0042] It should be noted that the inner wall of the through hole is also wrapped by the wrapping piece.

[0043] The present invention sets the thickness of the elastic lining so that the thickness gradually decreases outward along the through hole corresponding to the core hole, so that the elastic lining has a structure with a thick center and a thin outside, which is equivalent to increasing the structural strength of the connection with the valve stem. When the diaphragm body is installed on the constant pressure valve, this structure is not only easier to push the valve stem to move when deformation occurs, but also reduces the loss of the diaphragm body at the through hole position due to deformation, and is less likely to cause the fan blades in the traditional structure to get stuck. It also reduces the leakage problem at the structural connection (here refers to the connection between the valve stem and the diaphragm), and correspondingly improves the service life of the diaphragm body. Since the diaphragm body of the present invention dynamically adjusts the flow control in actual application, its operation frequency is relatively high. According to the above setting, after improving the service life of the diaphragm body, the service life of the constant pressure valve is also correspondingly extended, improving the safety of the equipment.

[0044] In order to further enhance the structural strength of the connection between the diaphragm body and the valve stem (i.e., the structural strength within a certain distance around the through hole), the thickness of the elastic lining member can be further set according to the following structural settings: in some embodiments, the thickness of the elastic lining member remains consistent within a certain distance around the through hole, and then gradually decreases as it continues to extend outward.

[0045] like Figure 1 The structure shown can be regarded as a cross-sectional schematic structure of a diaphragm body formed by an elastic lining part with a circular sheet structure and a wrapping part and a protective layer provided on the outside, wherein the thickness of the elastic lining part remains consistent during the process of extending a certain distance from its through hole to the outside, and then the thickness gradually decreases during the subsequent extension process.

[0046] In some preferred embodiments, the thickness of the elastic lining is set as follows: the elastic lining is set as a circular sheet structure, and the through hole is regarded as the center of the circular sheet structure. In the process of extending outward from the through hole to 1 / 2 of the radius of the circular sheet structure of the elastic lining, the thickness of the elastic lining remains unchanged, and then the thickness gradually decreases during the continued extension process.

[0047] The wrapping member of the present invention is made of nitrile rubber, which wraps the outer periphery of the elastic lining member. The structure is a fully wrapped structure, including the inner wall of the through-hole structure of the lining member at the core hole position, which is also wrapped with nitrile rubber.

[0048] In order to facilitate the installation of the composite diaphragm in the valve cavity, positioning bosses can be provided on both opposite side surfaces of the edge of the wrapping member.

[0049] Specifically, such as Figure 1As shown, at the edge of the wrapping member 402, after positioning bosses 404 are provided on both the upper and lower surfaces thereof, the wrapping member 402 is provided with a structure that is raised upward, downward, and outward at its outer edge (the outward raised structure is actually a boss structure formed by the outer edge of the wrapping member 402 itself relative to the upward and downward positioning bosses). When the diaphragm body is installed in the valve cavity, as shown in FIG. Figure 3 As shown, the joint between the upper and lower valve covers can be configured as a concave structure, into which the edge of the diaphragm body is embedded. In this case, the two positioning bosses on the upper and lower sides of the wrapper respectively contact the inner walls of the two independent chambers separated by the diaphragm body through their outward-facing sides. This ensures that no matter which side of the separated chamber the diaphragm body deforms, the positioning bosses contacting the inner wall of the corresponding chamber will fit more tightly, which effectively enhances the sealing performance of the structural connection (i.e., the sealing performance between the edge of the diaphragm body and the inner wall of the valve chamber is stronger).

[0050] In the present invention, the protective layer 403 is made of any one of nitrile rubber (NBR), ethylene propylene diene monomer (EPDM) and polytetrafluoroethylene (PTFE). Figure 1 As shown, a protective layer 403 made of polytetrafluoroethylene (PTFE) is provided on the lower surface of the packaging member 402.

[0051] It should be noted that in actual implementation, a composite protective layer of NBR, EPDM, and PTFE can be appropriately combined according to actual needs. By providing a PTFE coating as the protective layer in contact with the fluid, the valve equipped with this composite diaphragm can meet sanitary valve standards.

[0052] In some embodiments, the protective layer 403 includes an upper protective layer and a lower protective layer, disposed on opposing surfaces of the wrapping member. That is, the protective layer 403 is provided on both the surface of the wrapping member 402 facing the upper valve cavity and the surface facing the lower valve cavity. With this structural arrangement, the wrapping member 402, after being covered with the elastic lining member 401, has opposing surfaces. After the diaphragm body is installed in the valve cavity, either surface of the wrapping member 402 faces one of the two chambers separated by the diaphragm body.

[0053] like Figure 3As shown, an upper protective layer is provided on the upper surface of the wrapping member, the upper protective layer facing the upper chamber, and a lower protective layer is provided on the lower surface of the wrapping member, the protective layer facing the lower chamber. In the present invention, in some typical applications, the fluid flows through the lower chamber, and the power to drive the deformation of the diaphragm body comes from the compressed air introduced into the upper chamber (here, it means that the power to drive the deformation of the composite diaphragm is actually the pressure difference between the two chambers. The pressure of the upper chamber is controlled by the introduction of compressed air, and the pressure of the lower chamber is generated by the fluid flowing through the chamber. The deformation of the diaphragm can be controlled by dynamically adjusting the amount of compressed air introduced, so that the flow rate in the lower chamber remains constant).

[0054] In order to facilitate the provision of a protective layer on the surface of the wrapping piece and prevent it from falling off during use, the utility model can provide a recessed structure on both opposite sides of the wrapping piece, and a protective layer is provided in each recessed structure.

[0055] In some embodiments, the upper protective layer (the protective layer facing the upper valve cavity, disposed on the upper surface of the wrapping member) is made of nitrile rubber, and the lower protective layer (the protective layer facing the lower valve cavity, disposed on the lower surface of the wrapping member, in contact with the material) is made of PTFE.

[0056] In actual application, the present invention can be configured as follows to meet food grade application standards:

[0057] In some embodiments, the lower protective layer is formed by directly coating the lower surface of the package with PTFE;

[0058] In other embodiments, the lower protective layer is a mixed coating of PTFE + EPDM rubber, which refers to EPDM coated with PTFE, making the surface flat and smooth, eliminating the slight pressure effect caused by small potholes on the surface.

[0059] The utility model also provides a constant pressure valve, such as Figure 3 As shown, it includes an upper valve seat 101, a lower valve seat 102, a valve stem 200 and a valve core 300. A composite diaphragm 400 is provided in the valve cavity formed by the upper valve seat 101 and the lower valve seat 102 covering each other, and the valve stem 200 passes through the composite diaphragm 400 and is connected to the valve core 300.

[0060] Specifically, the top of the upper valve seat 101 has an axial hole so that one end of the valve stem 200 (the top of the second section of the stem 202 in the illustrated structure) passes through, and the upper valve seat 101 is also provided with an air source interface (not shown in the illustrated structure, refer to Figure 5 The interface 50') is convenient for connecting the compressed air source and then passing the compressed air into the upper valve cavity to control the pressure of the cavity;

[0061] The other end of the valve stem 200 (i.e., the bottom end of the second section of the stem 202) passes through the composite diaphragm 400 and is connected to the valve core 300;

[0062] The lower valve seat 102 has two openings, opening 601 and opening 602, which can serve as a fluid inlet and outlet, respectively, depending on the actual situation. The valve core 300 is located at opening 602 and, driven by the valve stem 200, moves in and out of opening 602, thereby controlling the flow of fluid through the opening.

[0063] It should be noted that in order to ensure the sealing of the composite diaphragm and the valve stem at the connection (i.e., the sealing of the position where the valve stem passes through the composite diaphragm), the valve stem can be set to a two-section structure, and any one section of the stem in the two-section valve stem structure can be quickly connected to the other section of the stem (for example, a snap-on connection structure or a threaded connection structure). The composite diaphragm is set at the connection of the two-section structure. Through the squeezing of each segmented stem during connection of the two-section structure, the wrapping of the composite diaphragm is squeezed to form a sealing effect. In comparison, in the traditional structure, structures such as fixing rings and sealing rings need to be set at the position where the valve stem passes through the elastic deformation component. Not only is the installation troublesome, there are many structural parts, and the structural parts are prone to aging. Figure 3 As shown, the valve stem 200 is set to a two-section structure, including a first rod body 201 and a second rod body 202. The second rod body 202 has a boss structure in its middle section. The first rod body 201 is screwed into the second rod body 202 and is restricted by the boss and cannot continue to screw downward. The composite diaphragm 400 is inserted into the stop point (in actual operation, the composite diaphragm 400 is first inserted into the upper section of the boss of the second rod body 202, and then the first rod body 201 is screwed thereon). During the tightening process of the two, the composite diaphragm 400 is squeezed to form a sealing structure at the connection.

[0064] In some embodiments, in order to ensure the sealing of the composite diaphragm and the valve stem during connection, the following structure can be set: Figure 2 As shown, the diaphragm body is provided with a boss structure at the edge of its core hole 4001 (the boss structure is provided on both the upper end face and the lower end face of the core hole). Correspondingly, as shown in FIG. Figure 3 As shown, a recessed structure is provided on the end face of any one section of the two-section valve stem 200 facing the other section of the stem (including the recessed structure on the boss of the second stem 202 and the recessed structure on the downward end face of the first stem 201). When the two sections of the stem are connected, the boss structure of the composite diaphragm 400 located at the core hole is embedded in the corresponding recessed structure. By squeezing the wrapping of the composite diaphragm when the two sections of the stem are connected, the sealing of the connection between the composite diaphragm 400 and the valve stem 200 can be greatly enhanced.

[0065] After the composite diaphragm is installed in the valve cavity of the constant pressure valve, in order to ensure the sealing effect and prevent the fluid from penetrating into the upper chamber, the structure can be arranged as follows: In some embodiments, such as Figure 3 As shown, another protective layer 4002 is provided on the composite diaphragm 400 , which is located on the surface of the composite diaphragm 400 in contact with the lower valve seat 102 . The protective layer 4002 is formed into a protective layer after being coated on the surface with PTFE.

[0066] In the above examples, compressed air is introduced into the upper valve chamber, and the lower valve chamber is a chamber for materials to flow through.

[0067] In summary, the composite diaphragm of the utility model is suitable for valve structures such as constant pressure valves. The upper and lower amplitudes of the valve are controlled at approximately ±9mm. The outer NBR rubber wraps the metal elastic lining to provide flexibility when the valve is actuated. The lining serves as a supporting structure to provide support when the valve moves up and down, preventing the diaphragm from deforming under high pressure, causing local stress concentration and diaphragm tearing. By providing a wrapping member and an elastic lining member, the elastic deformation component in the traditional constant pressure valve is integrated into the design and manufacturing, improving the safety of the structural parts and extending the service life of the product.

[0068] The above shows and describes the basic principles, main features and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited to the above embodiments. The above embodiments and descriptions are merely illustrative of the principles of the present invention. Various changes and improvements may be made to the present invention without departing from the spirit and scope of the present invention. Such changes and improvements are intended to fall within the scope of the present invention. The scope of protection claimed in this invention is defined by the appended claims and their equivalents.

Claims

1. A composite diaphragm, comprising a diaphragm body, wherein the diaphragm body is a disc-shaped structure having a core hole for facilitating passage of a valve stem, characterized in that: The diaphragm body includes an elastic lining, a wrapping member and a protective layer. The elastic lining member is in a disc-shaped structure, the wrapping member is wrapped around the elastic lining member, and the protective layer is provided on the outer surface of the wrapping member; A positioning boss is provided on the edge of the wrapping piece.

2. The composite diaphragm according to claim 1, characterized in that: The elastic lining member is made of stainless steel.

3. The composite diaphragm according to claim 1, characterized in that: The elastic lining member is provided with a through hole corresponding to the core hole, and the thickness of the elastic lining member gradually decreases outward along the through hole.

4. The composite diaphragm according to claim 1, characterized in that The wrapping piece is made of nitrile rubber.

5. The composite diaphragm according to claim 1, characterized in that: Positioning bosses are provided on both opposite side surfaces of the edge of the wrapping piece.

6. The composite diaphragm according to claim 1, characterized in that: The protective layer is made of any one of nitrile rubber, EPDM rubber and polytetrafluoroethylene.

7. The composite diaphragm according to claim 1, characterized in that: The protective layer includes an upper protective layer and a lower protective layer, which are respectively arranged on two opposite sides of the packaging piece.

8. The composite diaphragm according to claim 7, characterized in that: Two opposite surfaces of the wrapping piece are each provided with a recessed structure, and a protective layer is provided in any of the recessed structures.

9. A constant pressure valve, comprising an upper valve seat, a lower valve seat, a valve stem and a valve core, wherein the upper valve seat and the lower valve seat overlap each other to form a valve cavity, and the valve stem passes through the valve cavity and is connected to the valve core, characterized in that: The valve cavity is provided with a composite diaphragm according to any one of claims 1 to 8, and the composite diaphragm divides the valve cavity into two independent upper and lower chambers. The valve stem passes through the composite diaphragm and is connected to the valve core.

10. The constant pressure valve according to claim 9, characterized in that Another protective layer made of PTFE is provided on the composite diaphragm and is located on the surface of the composite diaphragm that contacts the lower valve seat.

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