A back pressure valve

Abstract

The present application relates to a back pressure valve, which includes a valve body with a split structure. An inflow channel and an outflow channel are provided inside the valve body. A piston mounting hole is provided at the connection of the inflow channel and the outflow channel. A piston that can connect or cut off the inflow channel and the outflow channel is installed in the piston mounting hole in a guiding and moving manner. The outer wall of the piston is in sealing cooperation with the cavity wall of the piston mounting hole. An elastic member mounting hole is also provided inside the valve body. An elastic member is provided in the elastic member mounting hole. One end of the elastic member presses against the piston, and the other end of the elastic member presses against the cavity wall of the elastic member mounting hole. The elastic member provides an elastic force for driving the piston to cut off the inflow channel and the outflow channel, and the inflow liquid entering the valve body from the inflow channel provides a liquid pressure for driving the piston to connect the inflow channel and the outflow channel. The back pressure valve of the present application cuts off or opens the connection of the inflow channel and the outflow channel through the movement of the piston, and the piston is not easily damaged during use, thereby prolonging the service life of the back pressure valve.

Description

Technical Field

[0001] This application relates to the field of valves, and particularly to a back pressure valve. Background Art

[0002] The term "back pressure valve" comes from "Back Pressure Valve". It means that a certain pressure is formed due to the function of the valve, and the pressure can generally be adjusted. It can be used to control the flow of various types of fluids such as air, water, steam, various corrosive media, mud, oil products, liquid metals, and radioactive media.

[0003] Refer to Figure 1 , in the related art, a back pressure valve is disclosed, which includes an upper valve cover 91 and a lower valve cover 92. An inlet passage 93 and an outlet passage 94 are provided in the lower valve cover 92. A diaphragm 95 that can cut off or connect the inlet passage 93 and the outlet passage 94 by deformation is provided at the connection of the inlet passage 93 and the outlet passage 94. The periphery of the diaphragm 95 is clamped between the upper valve cover 91 and the lower valve cover 92. A spring member 96 for pressing the middle part of the diaphragm 95 is provided in the upper valve cover 91. The back pressure valve realizes the movement of the diaphragm 95 through the interaction of the elastic force of the built-in spring member 96 and the system pressure: when the system pressure is smaller than the set pressure, the diaphragm 95 cuts off the inlet passage 93 and the outlet passage 94 under the action of the elastic force of the spring member 96; when the system pressure is larger than the set pressure, the diaphragm 95 deforms under the action of the system pressure, the middle part bulges towards the spring member 96, and at the same time the spring member 96 is compressed, the inlet passage 93 and the outlet passage 94 are connected, and the liquid passes through the back pressure valve.

[0004] The defect in the above-mentioned related art is that during the use of the back pressure valve, the liquid impacts the diaphragm 95 for a long time, and the repeated deformation of the diaphragm 95 easily causes the diaphragm 95 to be damaged, thereby shortening the service life of the back pressure valve. Summary of the Invention

[0005] In order to improve the technical problem of the short service life of the above-mentioned back pressure valve, this application provides a back pressure valve.

[0006] The back pressure valve provided by this application adopts the following technical solutions:

[0007] A backpressure valve includes a valve body with a split structure. An inflow channel and an outflow channel are provided in the valve body. A piston mounting hole is provided at the connection of the inflow channel and the outflow channel. A piston that can connect or cut off the inflow channel and the outflow channel is installed in the piston mounting hole in a guiding and moving manner. The outer wall of the piston is in sealing cooperation with the cavity wall of the piston mounting hole. An elastic member mounting hole is also provided in the valve body. An elastic member is provided in the elastic member mounting hole. One end of the elastic member presses against the piston, and the other end of the elastic member presses against the cavity wall of the elastic member mounting hole. The elastic member provides an elastic force to drive the piston to cut off the inflow channel and the outflow channel, and the inflow liquid entering the valve body from the inflow channel provides a liquid pressure to drive the piston to connect the inflow channel and the outflow channel.

[0008] By adopting the above technical solution, when the backpressure valve of the present application is in use, a piston mounting hole is provided at the connection of the inflow channel and the outflow channel, and a piston is provided in the piston mounting hole. When the pressure of the inflow liquid entering the valve body from the inflow channel acting on the piston is less than the initial elastic force of the elastic member, the piston cuts off the inflow channel and the outflow channel; when the pressure of the inflow liquid entering the valve body from the inflow channel acting on the piston is greater than the elastic force of the elastic member, the piston moves, so that the inflow channel and the outflow channel are connected. The backpressure valve of the present application cuts off or opens the connection of the inflow channel and the outflow channel through the movement of the piston. The piston is not easily damaged during use, thereby prolonging the service life of the backpressure valve.

[0009] Preferably, a positive pressure groove is further provided on the side of the piston mounting hole away from the elastic member. The positive pressure groove is communicated with the inflow channel. The inlet of the outflow channel is communicated with the bottom wall of the positive pressure groove, and the inlet of the outflow channel protrudes upward from the bottom wall of the positive pressure groove. The end surface of the piston away from the elastic member is used to press against the inlet edge or away from the inlet edge to realize the cutting off or connection of the inflow channel and the outflow channel, and the projected area of the end surface of the piston away from the elastic member in the moving direction of the piston is greater than the area enclosed by the projected outer edge of the inlet edge in the moving direction of the piston.

[0010] Preferably, the piston includes a moving member and a guiding and limiting member. A guiding hole is provided on the guiding and limiting member. The outer wall of the guiding and limiting member is in sealing cooperation with the cavity wall of the piston mounting hole. A blocking and matching structure is further provided on the cavity wall of the piston mounting hole near the elastic member mounting hole. The blocking and matching structure is used for blocking and matching with the end surface of the guiding and limiting member near the elastic member mounting hole;

[0011] The moving member includes a guiding part and a pressing part. The guiding part is installed in the guiding hole of the guiding and limiting member in a guiding and moving manner, and the guiding part is in sealing cooperation with the wall of the guiding hole of the guiding and limiting member. The piston is in pressing cooperation with the elastic member through the end surface of the guiding part of the moving member. The piston presses against the inlet edge or away from the inlet edge through the end surface of the pressing part of the moving member to realize the cutting off or connection of the inflow channel and the outflow channel.

[0012] By adopting the above technical solution, it is possible to avoid the mutual friction between the piston and the cavity wall of the piston mounting hole. When replacing and repairing, only the piston needs to be replaced, which is very convenient.

[0013] Preferably, the pressing part protrudes outward perpendicular to the piston moving direction compared with the guiding part to form a step surface. A gap for liquid to pass through is left between the pressing part and the cavity wall of the piston mounting hole. A reverse pressure groove is formed between the step surface and the guiding limiting part. The liquid in the forward pressure groove can enter the reverse pressure groove through the gap. And the difference between the projected area of the end surface of the pressing part of the moving part in the piston moving direction and the area enclosed by the outer edge of the inlet edge in the piston moving direction is greater than the projected area of the step surface in the piston moving direction.

[0014] By adopting the above technical solution, the pressure exerted on the convex part of the piston by the liquid entering the reverse pressure groove partially offsets the pressure exerted on the piston by the forward pressure groove, thereby reducing the pressure that the elastic part needs to bear. Furthermore, when the maximum pressure that the elastic part can bear remains unchanged, the liquid pressure required for the back pressure valve to flow is increased, so that the back pressure valve can be applied to a hydraulic system with a higher pressure.

[0015] Preferably, an installation groove is further formed on the end surface of the pressing part of the moving part. An anti-corrosion seal is fixedly installed in the installation groove. The circumferential side wall of the anti-corrosion seal is in sealing cooperation with the groove wall of the installation groove. The anti-corrosion seal is used to press against the inlet edge or away from the inlet edge to cut off or connect the inflow channel and the outflow channel.

[0016] By adopting the above technical solution, the part of the piston used to cut off the inlet at the inlet edge is not easily corroded and has better sealing performance.

[0017] Preferably, a pressure regulating mechanism is further provided on the valve body. The pressure regulating mechanism includes a top pressing plate and an adjusting bolt. A threaded hole penetrating the cavity wall is provided on the cavity wall of the elastic part mounting hole away from the piston. The screw part of the adjusting bolt is screwed into the threaded hole and the length of the screw part is greater than the depth of the threaded hole. The head of the adjusting bolt is located outside the elastic part mounting hole. The top pressing plate is arranged in the elastic part mounting hole. One end of the top pressing plate is in top pressing cooperation with the end of the elastic part away from the piston, and the other end of the top pressing plate is in top pressing cooperation with the screw part of the adjusting bolt.

[0018] By adopting the above technical solution, the initial elastic force of the elastic part can be adjusted as needed, and then the liquid pressure required for the liquid to flow in the back pressure valve can be adjusted.

[0019] Preferably, a hemispherical pressing portion is provided at the end of the screw portion of the adjusting bolt, and a curved groove cooperating with the hemispherical pressing portion is provided on the pressing plate.

[0020] By adopting the above technical solution, the adjusting bolt can press the pressing plate more stably.

[0021] Preferably, a protective cover is further provided outside the adjusting bolt, including a cylindrical side wall with openings at both ends and a protective cover detachably fixed at one opening of the side wall. A connecting plate is further formed at the middle position inside the side wall. A threaded hole for the screw portion of the adjusting bolt to pass through is provided on the connecting plate. The connecting plate divides the space inside the side wall into a first space close to the protective cover and a second space far from the protective cover. The head of the adjusting bolt is located in the first space, and the screw portion of the adjusting bolt is located in the second space, and the protective cover can be sleeved outside the valve body portion where the elastic member mounting hole is located.

[0022] By adopting the above technical solution, the protective cover can protect the adjusting bolt from being damaged.

[0023] Preferably, flange structures for facilitating connection are fixedly provided at the inlet of the inflow channel and the outlet of the outflow channel. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 is a schematic cross-sectional structure view of the back pressure valve in the background art;

[0025] Figure 2 is a schematic three-dimensional structure view of the back pressure valve according to an embodiment of the present application;

[0026] Figure 3 is Figure 2 the right view of the back pressure valve in

[0027] Figure 4 is Figure 3 the schematic cross-sectional structure view at A-A in

[0028] Figure 5 is Figure 4 the enlarged view of the structure at B in

[0029] Description of reference numerals: 1. Upper valve body; 11. Elastic member mounting hole; 111. Elastic member; 12. Piston mounting hole; 13. Stopping surface; 2. Lower valve body; 21. Inflow channel; 22. Outflow channel; 221. Inlet edge; 23. Positive pressure groove; 3. Protective cover; 31. Side wall; 32. Protective cover; 33. Connecting plate; 34. First space; 35. Second space; 4. Flange structure; 5. Piston; 51. Moving member; 511. Guide portion; 512. Pressing portion; 513. Step surface; 514. Mounting groove; 515. Anticorrosion seal; 52. Guide and limit member; 521. Guide hole; 6. Gap; 7. Reverse pressure groove; 8. Pressure regulating mechanism; 81. Top pressing plate; 82. Adjusting bolt; 821. Hemispherical top pressing portion; 91. Upper valve cover; 92. Lower valve cover; 93. Inlet channel; 94. Outlet channel; 95. Diaphragm; 96. Spring member. Detailed implementation manners

[0030] The present application will be further described in detail below with reference to the accompanying drawings.

[0031] Referring to Figure 2 and Figure 3 , an embodiment of the present application discloses a back pressure valve, which includes an upper valve body 1 and a lower valve body 2. Referring to Figure 4 , the back pressure valve further includes a pressure regulating mechanism 8 located on the upper valve body 1 and a protective cover 3 installed outside the pressure regulating mechanism 8. The upper valve body 1 and the lower valve body 2 are fixedly connected by bolts to form an integral body.

[0032] Continuing to refer to Figure 4 , an inflow channel 21, a positive pressure groove 23 and an outflow channel 22 are provided in the lower valve body 2. The inflow channel 21 is communicated with the positive pressure groove 23, the inlet of the outflow channel 22 is communicated with the bottom wall of the positive pressure groove 23, and the inlet edge 221 of the outflow channel 22 protrudes upward from the bottom wall of the positive pressure groove 23, so that the shape of the positive pressure groove 23 is annular. Flange structures 4 for facilitating connection are provided at both the inlet of the inflow channel 21 and the outlet of the outflow channel 22.

[0033] Referring to Figure 4 and Figure 5 , a communicated elastic member mounting hole 11 and a piston mounting hole 12 are provided in the upper valve body 1. The piston mounting hole 12 is correspondingly arranged with the positive pressure groove 23, and the piston mounting hole 12 is located between the elastic member mounting hole 11 and the positive pressure groove 23. The elastic member mounting hole 11 and the piston mounting hole 12 are coaxially arranged, and the aperture of the piston mounting hole 12 is larger than that of the elastic member mounting hole 11. A stopping surface 13 is formed at the junction of the elastic member mounting hole 11 and the piston mounting hole 12.

[0034] Continuing to refer to Figure 4 and Figure 5, a piston 5 is installed in the piston mounting hole 12 in a guiding and moving manner. The piston 5 includes a moving member 51 and a guiding and limiting member 52. A guiding hole 521 is provided on the guiding and limiting member 52, and a sealing ring is provided on the outer wall of the guiding and limiting member 52. The outer wall of the guiding and limiting member 52 is in guiding and moving and sealing fit with the cavity wall of the piston mounting hole 12. In other embodiments, the guiding and limiting member 52 can also be fixedly arranged on the cavity wall of the piston mounting hole 12. When the guiding and limiting member 52 moves towards the elastic member mounting hole 11, the stopping surface 13 limits the movement of the guiding and limiting member 52, and the stopping surface 13 forms a stopping and matching structure for stopping and matching with the end surface of the guiding and limiting member 52 close to the elastic member mounting hole 11.

[0035] Continue to refer to Figure 4 and Figure 5 , the moving member 51 includes a guiding portion 511 and a pressing portion 512. The guiding portion 511 is installed in the guiding hole 521 of the guiding and limiting member 52 in a guiding and moving manner, and a sealing ring is provided on the guiding portion 511. The guiding portion 511 is in sealing fit with the wall of the guiding hole 521 of the guiding and limiting member 52. The pressing portion 512 protrudes outward along a direction perpendicular to the moving direction of the piston 5 compared with the guiding portion 511 to form a step surface 513. An installation groove 514 is further opened on the end surface of the pressing portion 512, and an anti-corrosion sealing member 515 is fixedly installed in the installation groove 514 by screws. A sealing ring is provided on the circumferential side wall of the installation groove 514, and the anti-corrosion sealing member 515 is in sealing fit with the groove wall of the installation groove 514 through the sealing ring. The piston 5 is pressed against the inlet edge 221 or away from the inlet edge 221 through the anti-corrosion sealing member 515 on the end surface of the pressing portion 512 to realize the truncation or connection of the inflow channel 21 and the outflow channel 22. In this embodiment, the anti-corrosion sealing member 515 is made of tetrafluoroethylene material. A gap 6 for liquid to pass through is left between the pressing portion 512 and the cavity wall of the piston mounting hole 12, and a reverse pressure groove 7 is formed between the step surface 513 and the guiding and limiting member 52. The liquid in the forward pressure groove 23 can enter the reverse pressure groove 7 through the gap 6. The projected area of the end surface of the pressing portion 512 of the moving member 51 in the moving direction of the piston 5 is larger than the area enclosed by the projection of the outer edge of the inlet edge 221 in the moving direction of the piston 5, and the difference between the projected area of the end surface of the pressing portion 512 of the moving member 51 in the moving direction of the piston 5 and the area enclosed by the projection of the outer edge of the inlet edge 221 in the moving direction of the piston 5 is larger than the projected area of the step surface 513 in the moving direction of the piston 5. The advantage of such a design is that the pressure of the liquid in the reverse pressure groove 7 can partially offset the pressure of the liquid in the forward pressure groove 23, thereby reducing the pressure that the elastic member 111 needs to bear. Furthermore, when the maximum pressure that the elastic member 111 can bear remains unchanged, the liquid pressure during the flow of the back pressure valve is increased, so that the back pressure valve can be applied to a hydraulic system with a higher pressure.

[0036] Continue to refer to Figure 4, an elastic member 111 is arranged in the elastic member installation hole 11. In this embodiment, the elastic member 111 is preferably a spring. One end of the spring presses against the end face of the guiding portion 511, and the other end of the spring presses against the pressure regulating mechanism 8. The pressure regulating mechanism 8 includes a top pressing plate 81 and an adjusting bolt 82. A threaded hole penetrating through the cavity wall is arranged on the cavity wall of the elastic member installation hole 11 on the side away from the piston 5. The screw portion of the adjusting bolt 82 is screwed into the threaded hole, and the length of the screw portion is greater than the depth of the threaded hole. The head of the adjusting bolt 82 is located outside the elastic member installation hole 11. The top pressing plate 81 is arranged in the elastic member installation hole 11, and the top pressing plate 81 is in guiding movement cooperation with the hole wall of the elastic member installation hole 11. One end of the top pressing plate 81 presses against the end of the spring away from the piston 5, and the other end of the top pressing plate 81 presses against the screw portion of the adjusting bolt 82. A hemispherical pressing portion 821 is arranged at the end of the screw portion of the adjusting bolt 82, and a curved groove matching with the hemispherical pressing portion 821 is arranged on the top pressing plate 81. The advantage of such a design is that the adjusting bolt 82 can press the top pressing plate 81 more stably. When using the pressure regulating mechanism 8 to adjust the liquid pressure required for the liquid to flow through the back pressure valve, by screwing the adjusting bolt 82, the length of the screw portion of the adjusting bolt 82 extending into the elastic member installation hole 11 changes, thereby driving the deformation amount of the spring compressed by the top pressing plate 81 to change, and further changing the elastic force exerted by the spring on the piston 5.

[0037] Continue to refer to Figure 4 , a protective cover 3 is further arranged outside the adjusting bolt 82. The protective cover 3 includes a cylindrical side wall 31 with openings at both ends and a protective cover 32 fixedly connected to one opening of the side wall 31 by clamping. A connecting plate 33 is further formed at the middle position inside the side wall 31, and a threaded hole for the screw portion of the adjusting bolt 82 to pass through is arranged on the connecting plate 33. The connecting plate 33 divides the space inside the side wall 31 into a first space 34 close to the protective cover 32 and a second space 35 away from the protective cover 32. The head of the adjusting bolt 82 is located in the first space 34, and the screw portion of the adjusting bolt 82 is located in the second space 35. The opening size of the protective cover 3 is larger than the size of the valve body portion where the elastic member installation hole 11 is located, so that the protective cover 3 can be sleeved outside the valve body portion where the elastic member installation hole 11 is located. The protective cover 3 can protect the adjusting bolt 82 from being damaged. When it is necessary to screw the adjusting bolt 82, the protective cover 32 can be disassembled, and then the adjusting bolt 82 can be screwed. Moreover, when the adjusting bolt 82 is screwed, the protective cover 3 can move together with the adjusting bolt 82 and be sleeved outside the valve body portion where the elastic member installation hole 11 is located without interference.

[0038] The implementation principle of the embodiment of this application is as follows: When the back-pressure valve is in use, the liquid in the hydraulic system enters the forward pressure groove 23 through the inflow channel 21, and then enters the reverse pressure groove 7 through the gap 6 between the pressing part 512 and the cavity wall of the piston mounting hole 12. The liquid pressures in the forward pressure groove 23 and the reverse pressure groove 7 are the same. However, since the difference between the projected area of the end face of the pressing part 512 in the moving direction of the piston 5 and the area enclosed by the projection of the outer edge of the inlet edge 221 in the moving direction of the piston 5 is greater than the projected area of the step surface 513 in the moving direction of the piston 5, the pressure of the liquid in the forward pressure groove 23 on the end face of the pressing part 512 is greater than the pressure of the liquid in the reverse pressure groove 7 on the step surface 513. When the difference between the pressure of the liquid in the forward pressure groove 23 on the end face of the pressing part 512 and the pressure of the liquid in the reverse pressure groove 7 on the step surface 513 is greater than the elastic force exerted by the spring on the piston 5, the piston 5 moves towards the elastic part mounting hole 11, and the inflow channel 21 and the outflow channel 22 are connected, and the liquid in the hydraulic system can pass through the back-pressure valve.

[0039] The back-pressure valve of this application cuts off or opens the connection between the inflow channel 21 and the outflow channel 22 by the movement of the piston 5. The piston 5 is not easily damaged during use, thereby prolonging the service life of the back-pressure valve; moreover, when the maximum pressure that the elastic part 111 can withstand remains unchanged, the liquid pressure required for the back-pressure valve to flow through can be increased, so that the back-pressure valve can be applied to a hydraulic system with a higher pressure.

[0040] The embodiments of this specific implementation manner are all preferred embodiments of this application, and do not limit the protection scope of this application accordingly. Therefore, all equivalent changes made according to the structure, shape, and principle of this application should be covered within the protection scope of this application.

Claims

1. A back pressure valve, comprising a valve body with a split structure, characterized in that: An inflow channel (21) and an outflow channel (22) are provided inside the valve body. A piston mounting hole (12) is provided at the connection of the inflow channel (21) and the outflow channel (22). A piston (5) that can connect or cut off the inflow channel (21) and the outflow channel (22) is installed in the piston mounting hole (12) in a guiding and movable manner. The outer wall of the piston (5) is in sealing cooperation with the cavity wall of the piston mounting hole (12). An elastic member mounting hole (11) is also provided inside the valve body. An elastic member (111) is provided inside the elastic member mounting hole (11). One end of the elastic member (111) presses against the piston (5), and the other end of the elastic member (111) presses against the cavity wall of the elastic member mounting hole (11). The elastic member (111) provides an elastic force to drive the piston (5) to cut off the inflow channel (21) and the outflow channel (22), and the inflow liquid entering the valve body from the inflow channel (21) provides a liquid pressure to drive the piston (5) to connect the inflow channel (21) and the outflow channel (22); A positive pressure groove (23) is further provided on the side of the piston mounting hole (12) away from the elastic member (111). The positive pressure groove (23) is connected to the inflow channel (21). The inlet of the outflow channel (22) is connected to the bottom wall of the positive pressure groove (23), and the inlet edge (221) of the outflow channel (22) protrudes upward from the bottom wall of the positive pressure groove (23). The end face of the piston (5) away from the elastic member (111) is used to press against the inlet edge (221) or away from the inlet edge (221) to achieve the cutting off or connection of the inflow channel (21) and the outflow channel (22), and the projected area of the end face of the piston (5) away from the elastic member (111) in the moving direction of the piston (5) is larger than the area enclosed by the projected outer edge of the inlet edge (221) in the moving direction of the piston (5); The piston (5) includes a moving member (51) and a guiding and limiting member (52). A guiding hole (521) is provided on the guiding and limiting member (52). The outer wall of the guiding and limiting member (52) is in sealing cooperation with the cavity wall of the piston mounting hole (12). A stop cooperation structure is further provided on the cavity wall of the piston mounting hole (12) near the elastic member mounting hole (11). The stop cooperation structure is used for stop cooperation with the end face of the guiding and limiting member (52) near the elastic member mounting hole (11); The moving member (51) includes a guiding portion (511) and a pressing portion (512). The guiding portion (511) is installed in the guiding hole (521) of the guiding and limiting member (52) in a guiding and movable manner, and the guiding portion (511) is in sealing cooperation with the wall of the guiding hole (521) of the guiding and limiting member (52). The piston (5) is in pressing cooperation with the elastic member (111) through the end face of the guiding portion (511) of the moving member (51). The piston (5) presses against the inlet edge (221) or away from the inlet edge (221) through the end face of the pressing portion (512) of the moving member (51) to achieve the cutting off or connection of the inflow channel (21) and the outflow channel (22); The pressing part (512) protrudes outward along a direction perpendicular to the moving direction of the piston (5) relative to the guiding part (511) to form a step surface (513). A gap (6) for liquid to pass through is left between the pressing part (512) and the cavity wall of the piston mounting hole (12). A reverse pressure groove (7) is formed between the step surface (513) and the guiding limiting part (52). The liquid in the forward pressure groove (23) can enter the reverse pressure groove (7) through the gap (6). Moreover, the projected area of the end surface of the pressing part (512) of the moving part (51) in the moving direction of the piston (5) and the area enclosed by the outer edge of the inlet edge (221) in the projection in the moving direction of the piston (5) have a difference greater than the projected area of the step surface (513) in the moving direction of the piston (5). An installation groove (514) is further formed on the end surface of the pressing part (512) of the moving part (51). An anti-corrosion seal (515) is fixedly installed in the installation groove (514). The circumferential side wall of the anti-corrosion seal (515) is in sealing cooperation with the groove wall of the installation groove (514). The anti-corrosion seal (515) is used to press against the inlet edge (221) or move away from the inlet edge (221) to cut off or connect the inflow channel (21) and the outflow channel (22). A pressure regulating mechanism (8) is further provided on the valve body. The pressure regulating mechanism (8) includes a top pressing plate (81) and an adjusting bolt (82). A threaded hole penetrating the cavity wall is provided on the cavity wall of the elastic member mounting hole (11) on the side away from the piston (5). The screw part of the adjusting bolt (82) is screwed into the threaded hole and the length of the screw part is greater than the depth of the threaded hole. The head of the adjusting bolt (82) is located outside the elastic member mounting hole (11). The top pressing plate (81) is arranged in the elastic member mounting hole (11). One end of the top pressing plate (81) is in top pressing cooperation with the end of the elastic member (111) away from the piston (5), and the other end of the top pressing plate (81) is in top pressing cooperation with the screw part of the adjusting bolt (82).

2. The back pressure valve according to claim 1, wherein: A hemispherical top pressing part (821) is provided at the end of the screw part of the adjusting bolt (82). A curved surface groove cooperating with the hemispherical top pressing part (821) is provided on the top pressing plate (81).

3. The back pressure valve according to claim 2, wherein: A protective cover (3) is further provided outside the adjusting bolt (82), which includes a cylindrical side wall (31) with openings at both ends and a protective cover (32) detachably and fixedly arranged at one opening of the side wall (31). A connecting plate (33) is further formed at the middle position inside the side wall (31). A threaded hole for the screw part of the adjusting bolt (82) to pass through is provided on the connecting plate (33). The connecting plate (33) divides the space inside the side wall (31) into a first space (34) close to the protective cover (32) and a second space (35) away from the protective cover (32). The head of the adjusting bolt (82) is located in the first space (34), and the screw part of the adjusting bolt (82) is located in the second space (35). Moreover, the protective cover (3) can be sleeved outside the valve body part where the elastic member mounting hole (11) is located.

4. The backpressure valve according to claim 1, characterized in that: Flange structures (4) facilitating connection are fixedly arranged at both the entrance of the inflow channel (21) and the exit of the outflow channel (22).

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