Pilot-operated type back pressure valve

Abstract

The pilot-operated type back pressure valve comprises a main valve structure, an inlet channel and an outlet channel are formed in the two ends of a main valve body of the main valve structure, and an air chamber is formed between a main valve cover and a main valve clack of the main valve structure; the pilot valve structure comprises an auxiliary valve body, an auxiliary valve cover, an auxiliary spring assembly arranged in the auxiliary valve cover and an auxiliary valve element assembly which is arranged in the auxiliary valve body and is in linkage with the auxiliary spring assembly, an inlet cavity, a middle cavity and a discharging cavity are formed in the auxiliary valve body, and a first passing opening is formed between the inlet cavity and the middle cavity; a second passing opening is formed between the middle cavity and the discharging cavity, the inlet channel of the main valve body is communicated with the inlet cavity in the auxiliary valve body through a first pipeline, the middle cavity of the auxiliary valve body is communicated with the air chamber of the main valve body through a second pipeline, and the discharging cavity of the auxiliary valve body is communicated with the outlet channel of the main valve body through a third pipeline. The valve is not affected by back pressure at the outlet end, it can be guaranteed that the valve is rapidly and accurately opened when the pressure set value is set, and the pipeline pressure is kept stable.

Description

Technical Field

[0001] This invention relates to the field of valve technology, and in particular to a pilot-operated back pressure valve. Background Technology

[0002] A back pressure valve is a special valve installed in a pipeline system, mainly used to maintain and stabilize the pressure at its inlet (upstream) end. It acts like a "pressure gatekeeper," applying a preset "reaction force" (i.e., back pressure) to the fluid to ensure that the upstream pressure does not fall below the set value. Thus, it plays a crucial role in various industrial applications, such as stabilizing pressure, preventing liquid siphoning, and providing stable operating conditions for metering pumps.

[0003] However, the performance of traditional back pressure valves is still affected by the back pressure at the outlet end. That is, when the back pressure at the outlet end of the back pressure valve is too high, the back pressure valve will not be able to open or close in time. Similarly, when the back pressure at the outlet end of the back pressure valve is unstable, it will also affect the opening pressure of the back pressure valve. When the fluctuation is large, it will cause frequent jumping or oscillation, resulting in a reduction in the service life of the valve.

[0004] Therefore, it is necessary to improve the existing back pressure valve so that it is not affected by the back pressure at the outlet end, thereby improving the reliability of the back pressure valve performance. Summary of the Invention

[0005] The purpose of this invention is to provide a pilot-operated back pressure valve. This invention is not affected by the back pressure at the outlet end, and can ensure that the valve opens quickly and accurately when the set pressure value is adjusted, maintain the stability of the pipeline pressure, and prevent the medium from flowing into the inlet, which greatly improves the reliability of the back pressure valve performance.

[0006] To achieve the above objectives, the present invention provides the following technical solution: a pilot-operated back pressure valve, comprising a main valve structure, wherein the main valve structure comprises a main valve body, an inlet channel and an outlet channel disposed at both ends of the main valve body, a main valve cover disposed at the upper end of the main valve body, a main valve sleeve disposed at the inner end of the main valve cover, a main valve disc slidably disposed vertically within the main valve sleeve, a main spring disposed at the upper end of the main valve disc for applying spring force to the main valve disc, and a main valve seat disposed within the main valve body for cooperating with the main valve disc, wherein an air chamber is formed between the main valve cover and the main valve disc; It also includes a pilot valve structure, which includes a secondary valve body, a secondary valve cover disposed on the upper end of the secondary valve body, a secondary spring assembly disposed in the secondary valve cover, and a secondary valve core assembly disposed in the secondary valve body and linked with the secondary spring assembly. A pressure stabilizing hole is provided through the side of the secondary valve cover. The secondary valve body is provided with an inlet cavity, a middle cavity, and a venting cavity. A first passage is provided between the inlet cavity and the middle cavity, and a second passage is provided between the middle cavity and the venting cavity. The inlet channel of the main valve body and the inlet cavity of the secondary valve body are connected through a first pipe. The middle cavity of the secondary valve body is connected to the air chamber of the main valve body through a second pipe. The venting cavity of the secondary valve body is connected to the outlet channel of the main valve body through a third pipe. Under the combined action of the secondary spring assembly and the medium thrust, the secondary valve core assembly has a first position with the first passage open and the second passage closed, and a second position with the first passage closed and the second passage open.

[0007] By adopting the above technical solution, when the main valve structure is closed, if the inlet channel pressure does not reach the set pressure of the pilot valve, the auxiliary valve core assembly of the pilot valve structure is in the first position, and the medium in the inlet channel of the main valve structure enters the gas chamber sequentially through the first pipe, inlet cavity, middle cavity, and second pipe. When the inlet channel pressure reaches the set pressure of the pilot valve structure, the auxiliary valve core assembly of the pilot valve structure moves upward to the second position, and the medium in the inlet channel of the main valve structure enters the outlet channel of the main valve sequentially through the first pipe, inlet cavity, middle cavity, venting cavity, and third pipe. At the same time, the main valve structure opens, and the medium in the gas chamber enters the outlet channel of the main valve sequentially through the second pipe, middle cavity, venting cavity, and third pipe. When the back pressure of the outlet channel is high, the medium in the outlet channel will sequentially enter the gas chamber through the third pipe, venting cavity, middle cavity, and second pipe, thereby preventing backflow of the medium. When the main valve structure is closed, even if there is no pressure in the inlet channel, the medium in the outlet channel can sequentially enter the gas chamber through the third pipe, venting cavity, middle cavity, and second pipe, causing the main valve disc to press tightly against the main valve seat, protecting the pipeline safety. This valve is unaffected by back pressure at the outlet end, ensuring rapid and accurate opening when the set pressure value is adjusted. It also prevents media from flowing into the inlet, greatly improving the reliability of the back pressure valve and maintaining pipeline pressure within 2%.

[0008] The invention is further configured such that the secondary valve body is hollow and open at both ends, an upper guide sleeve is sandwiched between the secondary valve body and the secondary valve cover, the upper guide sleeve extends into the inner cavity of the secondary valve body, the inlet cavity includes a first annular groove arranged circumferentially on the outer circumferential surface of the upper guide sleeve, a medium inlet arranged on the side of the secondary valve body and communicating with the first annular groove, an upper chamber arranged in the center of the upper guide sleeve, and a plurality of upper radial holes connecting the first annular groove and the upper chamber, an upper sealing ring is provided between the upper guide sleeve and the secondary valve body at positions corresponding to the upper and lower parts of the first annular groove, and the first passage is arranged at the lower end of the upper guide sleeve; the lower end of the inner cavity of the secondary valve body The base is threadedly connected. The venting chamber includes a second annular groove circumferentially disposed on the outer surface of the base, a venting outlet disposed on the side of the auxiliary valve body and communicating with the second annular groove, a lower chamber disposed on the base, and a plurality of lower radial holes communicating with the second annular groove and the lower chamber. A lower sealing ring is provided between the base and the auxiliary valve body at positions corresponding to the upper and lower parts of the second annular groove. An auxiliary valve seat is provided on the upper end of the lower chamber of the base, and the second through port is disposed on the auxiliary valve seat. The middle cavity is disposed between the upper guide sleeve and the base, and a medium outlet for connecting a second pipeline is provided through the middle cavity on the side of the auxiliary valve body.

[0009] By adopting the above technical solution, by installing an upper guide sleeve and a base with specific hole structures at the upper and lower ends of the valve body respectively, an inlet cavity, a middle cavity and a discharge cavity structure are formed inside the valve body, which is not only convenient to assemble, but also easy to process.

[0010] The present invention is further configured such that the secondary valve core assembly includes a valve core shaft and a piston rod arranged coaxially, the upper end of the piston rod abutting against the lower end of the valve core shaft, a first sealing ring is provided on the outer periphery of the valve core shaft, and a second sealing ring is provided on the secondary valve seat. When the secondary valve core assembly is in the first position, the lower end of the valve core shaft abuts against the first sealing ring to form a seal. When the secondary valve core assembly is in the second position, the second sealing ring abuts against the inner circular surface of the first passage to form a seal.

[0011] By adopting the above technical solution, it is possible to ensure effective sealing of the second port by the auxiliary valve core assembly in the first position, and effective sealing of the first port in the second position.

[0012] The invention is further configured such that the upper guide sleeve is fitted around the outer periphery of the valve core shaft, and a pressure-bearing sealing ring is provided between the valve core shaft and the upper guide sleeve at a position corresponding to the upper cavity. The inner circular surface of the first through-hole is in contact with the outer circular surface of the valve core shaft, and a plurality of flow guide grooves for connecting the upper cavity and the middle cavity are provided on the outer circular surface of the valve core shaft. The base is provided with a piston guide hole for the piston rod to extend into at a position corresponding to the lower end of the lower cavity. The outer circular surface of the piston rod is provided with a piston sealing ring for forming a sealing fit with the inner circular surface of the piston guide hole. The upper end of the piston rod abuts against the lower end of the valve core shaft. The lower end of the piston guide hole is also provided with a balance groove with an inner diameter smaller than that of the piston guide hole. The auxiliary valve body and the base are provided with a balance channel for connecting the middle cavity and the balance groove.

[0013] By adopting the above technical solution and setting a balance channel, when the auxiliary valve core assembly moves upward, the medium in the inlet channel of the main valve structure can sequentially enter the balance groove and piston guide hole through the first pipe, inlet cavity, middle cavity, and balance channel, ensuring the pressure difference between the upper and lower parts of the piston rod is balanced.

[0014] The invention is further configured such that a balance spring for applying an upward spring force to the piston rod is installed in the balance groove.

[0015] By adopting the above technical solution, the balance spring can counteract the influence of the piston rod's own weight, further ensuring the balance of the pressure difference between the upper and lower parts of the piston rod.

[0016] The present invention is further configured such that the balance channel includes a first radial hole extending radially from the outer circular surface of the base and communicating with the piston guide hole; a flow hole extending from the side of the piston rod to the bottom of the piston rod for communicating with the first radial hole and the balance groove; an annular guide groove disposed on the inner circular surface of the secondary valve body and communicating with the outer end of the first radial hole; a second radial hole and a third radial hole extending radially from the outer arm of the secondary valve body and communicating with the central cavity and the annular guide groove respectively; and a vertical hole extending upward from the bottom end of the secondary valve body and communicating with the second radial hole and the third radial hole. The outer ends of the second radial hole, the third radial hole and the vertical hole are all fitted with plugs.

[0017] By adopting the above technical solution, the balance channel can be processed by drilling without the need for casting. Therefore, this design greatly facilitates the early processing and also reduces processing costs.

[0018] The present invention is further configured such that the base is provided with an installation groove at the upper end of the venting chamber, the auxiliary valve seat is embedded in the installation groove, and the upper end of the auxiliary valve seat is provided with a positioning groove for positioning the second sealing ring. The upper end of the installation groove is threaded with a positioning sleeve, and a pressure ring is sandwiched between the positioning sleeve and the auxiliary valve seat. The inner circular surface of the pressure ring is provided with a pressing flange for pressing the second sealing ring onto the positioning groove, and an O-ring for forming a sealing fit with the inner circular surface of the installation groove is also installed on the outer circular surface of the pressure ring.

[0019] By adopting the above technical solution, when tightening the positioning screw sleeve, the positioning installation of the pressure ring, the auxiliary valve seat and the O-ring can be achieved. The structure is very reliable and the disassembly and assembly are very convenient.

[0020] The present invention is further configured such that the secondary spring assembly includes a guide sleeve installed on the upper end of the secondary valve cover, a push rod passing through the guide sleeve, a protective cover disposed on the upper end of the secondary valve cover to cover the upper end of the push rod, an upper spring seat and a lower spring seat sleeved on the outer periphery of the push rod, and a setter spring sandwiched between the upper spring seat and the lower spring seat. The lower end of the push rod is provided with a cone for pressing against the upper end of the secondary valve core assembly. The upper end of the upper spring seat abuts against the lower end of the guide sleeve, and the lower end of the lower spring seat abuts against the upper end of the cone.

[0021] By adopting the above technical solution, the auxiliary spring assembly can apply a stable spring force to the auxiliary valve core assembly, thereby realizing the setting of the pilot valve structure's set pressure. At the same time, by adjusting the axial height of the guide sleeve, the set pressure of the pilot valve structure can be adjusted.

[0022] The invention is further configured such that an emergency handle is hinged to the protective cover, an adjusting nut is threaded to the upper end of the top rod, and a washer is provided between the emergency handle and the adjusting nut.

[0023] By adopting the above technical solution, when the valve fails to open, the emergency manual opening handle can be used to force open the main valve structure and achieve full discharge.

[0024] The invention is further configured to include a check valve, wherein the first pipeline includes a front fitting and a rear fitting, the check valve includes a check valve body, the inlet end of the check valve body is connected to the inlet channel of the main valve body through the front fitting, the outlet end of the check valve body is threadedly connected to a check connector, the check connector is connected to the inlet cavity of the auxiliary valve body through the rear fitting, a check valve core is axially movable inside the check connector, the outer circular surface of the check valve core is provided with multiple vertically extending flow grooves, and the inner circular surface of the check connector near the lower end... The position also has a conical sealing surface, and a check valve core is equipped with a check sealing ring that forms a sealing fit with the conical sealing surface when it moves downward and abuts against it; the lower end of the check connector is also provided with a positioning groove, and a hollow filter screen cylinder with an open upper end is embedded in the positioning groove; the lower end of the check valve body is provided with a drain port, and a drain ball valve is installed at the drain port; a positioning spring is sandwiched between the inner end face of the drain ball valve and the filter screen cylinder; the outer end of the drain ball valve is connected to the outlet channel of the main valve body through a drain pipe.

[0025] By adopting the above technical solution, a check valve with a filtering function is added to the inlet end of the pilot valve structure, which can prevent the medium from flowing back and avoid abnormal system pressure or malfunction. At the same time, it can also prevent impurities from causing wear on the check valve core and the auxiliary valve core assembly of the pilot valve structure. The eccentric setting of the check valve inlet allows the medium to rotate and flush the filter screen, thereby preventing the filter screen from clogging and extending the filter screen replacement time. Attached Figure Description

[0026] Figure 1 This is a schematic diagram of the overall structure of the present invention; Figure 2 This is a schematic diagram of the pilot valve structure of the present invention; Figure 3 This is a schematic diagram of the pilot valve structure of the present invention after removing the secondary valve cover and the secondary spring assembly; Figure 4 This is a schematic diagram of the secondary valve core assembly of the present invention; Figure 5 This is a schematic diagram of the mounting structure of the secondary valve seat of the present invention; Figure 6 This is a schematic diagram of the mounting structure of the secondary spring assembly of the present invention; Figure 7 This is a schematic diagram of the check valve of the present invention.

[0027] In the diagram: 1. Main valve structure; 2. Main valve body; 3. Inlet channel; 4. Outlet channel; 5. Main valve cover; 6. Main valve sleeve; 7. Main valve disc; 8. Main spring; 9. Main valve seat; 10. Air chamber; 11. Pilot valve structure; 12. Secondary valve body; 13. Secondary valve cover; 14. Secondary spring assembly; 15. Secondary valve core assembly; 16. Pressure regulating hole; 17. Inlet cavity; 18. Middle cavity; 19. Relief cavity; 20. First port; 21. Second port; 22. First pipe; 23. Second pipe 24. Third pipe; 25. Upper guide sleeve; 26. First annular groove; 27. Medium inlet; 28. Upper chamber; 29. ​​Upper radial hole; 30. Upper sealing ring; 31. Base; 32. Second annular groove; 33. Discharge outlet; 34. Lower chamber; 35. Lower radial hole; 36. Lower sealing ring; 37. Secondary valve seat; 38. Medium outlet; 39. Valve spindle; 40. Piston rod; 41. First sealing ring; 42. Second sealing ring; 43. Pressure-bearing sealing ring; 44. Flow guide groove 45. Piston guide hole; 46. Piston seal ring; 47. Balance groove; 48. Balance channel; 49. Balance spring; 50. First radial hole; 51. Flow hole; 52. Annular guide groove; 53. Second radial hole; 54. Third radial hole; 55. Vertical hole; 56. Plug; 57. Mounting groove; 58. Positioning groove; 59. Positioning screw sleeve; 60. Pressure ring; 61. Pressing flange; 62. O-ring; 63. Guide sleeve; 64. Push rod; 65. Protective cover; 66. Upper spring 67. Lower spring seat; 68. Set spring; 69. Cone head; 70. Emergency handle; 71. Adjusting nut; 72. Gasket; 73. Check valve; 74. Front fitting; 75. Rear fitting; 76. Check valve body; 77. Check connector; 78. Check valve core; 79. Flow groove; 80. Conical sealing surface; 81. Check sealing ring; 82. Positioning groove; 83. Filter screen; 84. Drain outlet; 85. Drain ball valve; 86. Positioning spring; 87. Drain pipe. Detailed Implementation

[0028] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0029] Example: As attached Figures 1-7The pilot-operated back pressure valve shown includes a main valve structure 1, which includes a main valve body 2, an inlet channel 3 and an outlet channel 4 located at both ends of the main valve body 2, a main valve cover 5 located at the upper end of the main valve body 2, a main valve sleeve 6 located inside the main valve cover 5, a main valve disc 7 vertically slidably located within the main valve sleeve 6, a main spring 8 located at the upper end of the main valve disc 7 for applying spring force to the main valve disc 7, and a main valve seat 9 located within the main valve body 2 for cooperating with the main valve disc 7. A sealing ring is provided on the outer periphery of the main valve disc 7 to form a sealing fit with the inner periphery of the main valve sleeve 6. An air chamber 10 is formed between the main valve cover 5 and the main valve disc 7. The pilot-operated back pressure valve also includes a pilot valve structure 11, which includes a secondary valve body 12, a secondary valve cover 13 connected to the upper end of the secondary valve body 12 by screws, a secondary spring assembly 14 located within the secondary valve cover 13, and a secondary spring assembly 14 located within the secondary valve body 12 and cooperating with the secondary spring assembly 14. 4. A secondary valve core assembly 15 is formed by linkage. A pressure stabilizing hole 16 is provided through the side of the secondary valve cover 13. The secondary valve body 12 is provided with an inlet cavity 17, a middle cavity 18 and a venting cavity 19. A first passage 20 is provided between the inlet cavity 17 and the middle cavity 18. A second passage 21 is provided between the middle cavity 18 and the venting cavity 19. The inlet channel 3 of the main valve body 2 and the inlet cavity 17 in the secondary valve body 12 are connected by a first pipe 22. The middle cavity 18 of the secondary valve body 12 is connected to the air chamber 10 of the main valve body 2 by a second pipe 23. The venting cavity 19 of the secondary valve body 12 is connected to the outlet channel 4 of the main valve body 2 by a third pipe 24. Under the combined action of the secondary spring assembly 14 and the medium thrust, the secondary valve core assembly 15 has a first position with the first passage 20 open and the second passage 21 closed, and a second position with the first passage 20 closed and the second passage 21 open.When the main valve structure 1 is closed, if the pressure in the inlet channel 3 does not reach the set pressure of the pilot valve, the auxiliary valve core assembly 15 of the pilot valve structure 11 is in the first position, and the medium in the inlet channel 3 of the main valve structure 1 enters the gas chamber 10 sequentially through the first pipe 22, the inlet cavity 17, the middle cavity 18, and the second pipe 23; when the pressure in the inlet channel 3 reaches the set pressure of the pilot valve structure 11, the auxiliary valve core assembly 15 of the pilot valve structure 11 moves upward to the second position, and the medium in the inlet channel 3 of the main valve structure 1 enters the outlet channel 4 of the main valve sequentially through the first pipe 22, the inlet cavity 17, the middle cavity 18, the venting cavity 19, and the third pipe 24, while the main valve structure... When structure 1 is open, the medium in the air chamber 10 sequentially enters the outlet channel 4 of the main valve through the second pipe 23, the middle cavity 18, the relief cavity 19, and the third pipe 24. When the back pressure in the outlet channel 4 is high, the medium in the outlet channel 4 will sequentially enter the air chamber 10 through the third pipe 24, the relief cavity, the middle cavity 18, and the second pipe 23, thus preventing backflow of the medium. When structure 1 of the main valve is closed, even if there is no pressure in the inlet channel 3, the medium in the outlet channel 4 can sequentially enter the air chamber 10 through the third pipe 24, the relief cavity, the middle cavity 18, and the second pipe 23, causing the main valve disc 7 to press tightly against the main valve seat 9, protecting the pipeline safety. This valve is not affected by the back pressure at the outlet end, ensuring that the valve opens quickly and accurately when the set pressure value is adjusted, and preventing the medium from flowing back into the inlet, greatly improving the reliability of the back pressure valve performance, and maintaining the pipeline pressure within 2% fluctuation.

[0030] As attached Figures 2-5As shown, the secondary valve body 12 is hollow and open at both ends. An upper guide sleeve 25 is sandwiched between the secondary valve body 12 and the secondary valve cover 13. The upper guide sleeve 25 extends into the inner cavity of the secondary valve body 12, i.e., the outer circumference of the upper guide sleeve 25 has an upper limit step, and the inner circumference of the secondary valve body 12 has a lower limit step for abutting against the upper limit step to form a limit. The secondary valve cover 13 is pressed against the upper end of the upper guide sleeve 25 to achieve the fixed installation of the upper guide sleeve 25. The inlet cavity 17 includes a first annular groove arranged circumferentially on the outer circular surface of the upper guide sleeve 25. 26. A medium inlet 27 is disposed on the side of the secondary valve body 12 and communicates with the first annular groove 26; an upper chamber 28 is disposed at the center of the upper guide sleeve 25; and a plurality of upper radial holes 29 connecting the first annular groove 26 and the upper chamber 28. An upper sealing ring 30 is provided between the upper guide sleeve 25 and the secondary valve body 12 at positions corresponding to the upper and lower parts of the first annular groove 26. The first through-hole 20 is disposed at the lower end of the upper guide sleeve 25, that is, the first through-hole 20 is part of the inner hole of the upper guide sleeve 25 itself; the secondary valve body 12 The lower end of the inner cavity is threadedly connected to a base 31, meaning the outer circumference of the base 31 has an external thread. The lower end of the inner cavity of the secondary valve body 12 has an internal thread that matches the external thread. The lower end of the base 31 has an external hexagonal head. The base 31 is locked and fixed to the secondary valve body 12 by a lock nut. The discharge chamber 19 includes a second annular groove 32 circumferentially disposed on the outer surface of the base 31, a discharge outlet 33 disposed on the side of the secondary valve body 12 and communicating with the second annular groove 32, a lower chamber 34 disposed on the base 31, and a plurality of chambers for the second annular groove 32 to be discharged. A lower radial hole 35 connects the second annular groove 32 to the lower chamber 34. A lower sealing ring 36 is provided between the base 31 and the auxiliary valve body 12 at positions corresponding to the upper and lower parts of the second annular groove 32. An auxiliary valve seat 37 is provided on the upper part of the lower chamber 34, and the second passage 21 is provided on the auxiliary valve seat 37. The middle cavity 18 is provided between the upper guide sleeve 25 and the base 31. A medium outlet 38 for connecting the second pipeline 23 is provided through the side of the auxiliary valve body 12 at the position corresponding to the middle cavity 18. By installing the upper guide sleeve 25 and the base 31 with specific hole structures at the upper and lower ends of the valve body respectively, an inlet cavity 17, a middle cavity 18 and a discharge cavity 19 are formed inside the valve body, which is not only convenient for assembly, but also facilitates processing.

[0031] As attached Figures 2-5As shown, the secondary valve core assembly 15 includes a valve core shaft 39 and a piston rod 40 coaxially arranged. The upper end of the piston rod 40 abuts against the lower end of the valve core shaft 39. A first sealing ring 41 is provided on the outer periphery of the valve core shaft 39, and a second sealing ring 42 is provided on the secondary valve seat 37. When the secondary valve core assembly 15 is in the first position, the lower end of the valve core shaft 39 abuts against the first sealing ring 41 to form a seal. When the secondary valve core assembly 15 is in the second position, the second sealing ring 42 abuts against the inner circular surface of the first passage 20 to form a seal. This design can ensure effective sealing of the second passage 21 by the secondary valve core assembly 15 in the first position, and effective sealing of the first passage 20 by the secondary valve core assembly 15 in the second position.

[0032] As attached Figures 2-5 As shown, the upper guide sleeve 25 is fitted around the outer periphery of the valve spindle 39, and a pressure-bearing sealing ring 43 is provided between the valve spindle 39 and the upper guide sleeve 25 at a position corresponding to the upper chamber 28. The inner circular surface of the first through-hole 20 is in contact with the outer circular surface of the valve spindle 39, and multiple guide grooves 44 for connecting the upper chamber 28 and the middle chamber 18 are opened on the outer circular surface of the valve spindle 39. The cross-section of the valve spindle 39 corresponding to the position of the guide groove 44 can be designed as a regular hexagon or a regular square. The base 31 is... A piston guide hole 45 is provided at the lower end of the lower chamber 34 for the piston rod 40 to extend into. The outer surface of the piston rod 40 is provided with a piston sealing ring 46 for forming a sealing fit with the inner surface of the piston guide hole 45. The upper end of the piston rod 40 abuts against the lower end of the valve core shaft 39. The lower end of the piston guide hole 45 is also provided with a balance groove 47 with an inner diameter smaller than the piston guide hole 45. The auxiliary valve body 12 and the base 31 are provided with a balance channel 48 for connecting the middle chamber 18 and the balance groove 47. By setting the balance channel 48, when the auxiliary valve core assembly 15 moves upward, the medium in the inlet channel 3 of the main valve structure 1 can sequentially enter the balance groove 47 and the piston guide hole 45 through the first pipe 22, the inlet chamber 17, the middle chamber 18, and the balance channel 48, ensuring the pressure difference between the upper and lower parts of the piston rod 40 is balanced.

[0033] As attached Figure 3 As shown, a balance spring 49 is installed in the balance groove 47 to apply an upward spring force to the piston rod 40. The balance spring 49 can counteract the influence of the piston rod 40's own weight, further ensuring the balance of the pressure difference between the upper and lower parts of the piston rod 40.

[0034] As attached Figure 2 Appendix Figure 3As shown, the balance channel 48 includes a first radial hole 50 extending radially from the outer surface of the base 31 and communicating with the piston guide hole 45; a flow hole 51 (composed of a radial hole and an axial hole) extending from the side of the piston rod 40 to the bottom of the piston rod 40 for communicating with the first radial hole 50 and the balance groove 47; an annular guide groove 52 disposed on the inner surface of the secondary valve body 12 and communicating with the outer end of the first radial hole 50; a second radial hole 53 and a third radial hole 54 extending radially from the outer arm of the secondary valve body 12 and communicating with the central cavity 18 and the annular guide groove 52 respectively; and a vertical hole 55 extending upward from the bottom end of the secondary valve body 12 and communicating with the second radial hole 53 and the third radial hole 54. A plug 56 is installed at the outer end of the second radial hole 53, the third radial hole 54, and the vertical hole 55. The balance channel 48 can be machined by drilling, eliminating the need for casting. Therefore, this design greatly facilitates the initial machining process and reduces machining costs.

[0035] As attached Figure 5 As shown, the base 31 has an installation groove 57 at the upper end of the venting chamber 19. The auxiliary valve seat 37 is embedded in the installation groove 57, and the upper end of the auxiliary valve seat 37 has a positioning groove 58 for positioning the second sealing ring 42. A positioning sleeve 59 is threaded to the upper end of the installation groove 57. A pressure ring 60 is sandwiched between the positioning sleeve 59 and the auxiliary valve seat 37. The inner surface of the pressure ring 60 has a pressing flange 61 for pressing the second sealing ring 42 onto the positioning groove 58. An O-ring 62 is also installed on the outer surface of the pressure ring 60 to form a sealing fit with the inner surface of the installation groove 57. When the positioning sleeve 59 is tightened, the positioning installation of the pressure ring 60, the auxiliary valve seat 37, and the O-ring 62 can be achieved. The structure is very reliable and the disassembly and assembly are very convenient.

[0036] As attached Figure 6 As shown, the secondary spring assembly 14 includes a guide sleeve 63 mounted on the upper end of the secondary valve cover 13 (the upper end of the secondary valve cover 13 has a screw hole, and the outer periphery of the guide sleeve 63 has an external thread that mates with the screw hole), a push rod 64 passing through the guide sleeve 63, a protective cover 65 threaded to the upper end of the secondary valve cover 13 to cover the upper end of the push rod 64, an upper spring seat 66 and a lower spring seat 67 sleeved on the outer periphery of the push rod 64, and a setter spring 68 sandwiched between the upper spring seat 66 and the lower spring seat 67. The lower end of the push rod 64 is provided with a cone 69 for pressing against the upper end of the secondary valve core assembly 15. The upper end of the upper spring seat 66 abuts against the lower end of the guide sleeve 63, and the lower end of the lower spring seat 67 abuts against the upper end of the cone 69. The auxiliary spring assembly 14 can apply a stable spring force to the auxiliary valve core assembly 15, thereby setting the set pressure of the pilot valve structure 11. At the same time, the set pressure of the pilot valve structure 11 can be adjusted by adjusting the axial height of the guide sleeve 63.

[0037] As attached Figure 6As shown, an emergency handle 70 is also hinged to the protective cover 65. An adjusting nut 71 is threaded to the upper end of the top rod 64. A washer 72 is provided between the emergency handle 70 and the adjusting nut 71. The upper end of the handle has a protruding structure for abutting against the lower end of the washer 72. In the event of valve failure, the emergency manual opening handle can force the main valve structure 1 to open, achieving full discharge.

[0038] As attached Figure 1 Appendix Figure 7 As shown, the pilot-operated back pressure valve also includes a check valve 73. The first pipe 22 includes a front fitting 74 and a rear fitting 75. The check valve 73 includes a check valve body 76. The inlet end of the check valve body 76 is connected to the inlet channel 3 of the main valve body 2 through the front fitting 74. The outlet end of the check valve body 76 is threadedly connected to a check connector 77. The check connector 77 is connected to the inlet cavity 17 of the auxiliary valve body 12 through the rear fitting 75. A check valve core 78 is axially movable inside the check connector 77. The outer circular surface of the check valve core 78 fits against the inner circular surface of the check connector 77. The outer circular surface of the check valve core 78 is provided with multiple vertically extending flow grooves 79. The inner circular surface of the return connector 77 near the lower end is also provided with a conical sealing surface 80. The check valve core 78 is equipped with a check sealing ring 81 that forms a sealing fit with the conical sealing surface 80 when it moves downward and abuts against it. The lower end of the check connector 77 is also provided with a positioning groove 82. A hollow filter screen cylinder 83 with an open upper end is embedded in the positioning groove 82. The lower end of the check valve body 76 is provided with a drain port 84. A drain ball valve 85 is installed at the drain port 84. A positioning spring 86 is sandwiched between the inner end face of the drain ball valve 85 and the filter screen cylinder 83. The outer end of the drain ball valve 85 is connected to the outlet channel 4 of the main valve body 2 through a drain pipe 87. A check valve 73 with a filtering function is added to the inlet end of the pilot valve structure 11. This can prevent backflow of the medium, avoid abnormal system pressure or malfunction, and also prevent impurities from causing wear on the check valve core 78 and the auxiliary valve core assembly 15 of the pilot valve structure 11. The eccentric setting of the inlet of the check valve 73 allows the medium to rotate and flush the filter screen, thereby preventing the filter screen from clogging and extending the filter screen replacement time.

Claims

1. A pilot-operated back pressure valve, comprising a main valve structure (1), wherein the main valve structure (1) comprises a main valve body (2), an inlet channel (3) and an outlet channel (4) disposed at both ends of the main valve body (2), a main valve cover (5) disposed at the upper end of the main valve body (2), a main valve sleeve (6) disposed at the inner end of the main valve cover (5), a main valve disc (7) disposed vertically in the main valve sleeve (6), a main spring (8) disposed at the upper end of the main valve disc (7) for applying spring force to the main valve disc (7), and a main valve seat (9) disposed in the main valve body (2) for cooperating with the main valve disc (7), wherein an air chamber (10) is formed between the main valve cover (5) and the main valve disc (7); Its features are: It also includes a pilot valve structure (11), which includes a secondary valve body (12), a secondary valve cover (13) disposed at the upper end of the secondary valve body (12), a secondary spring assembly (14) disposed in the secondary valve cover (13), and a secondary valve core assembly (15) disposed in the secondary valve body (12) and linked with the secondary spring assembly (14). A pressure stabilizing hole (16) is provided through the side of the secondary valve cover (13). The secondary valve body (12) is provided with an inlet cavity (17), a middle cavity (18), and a discharge cavity (19). A first passage (20) is provided between the inlet cavity (17) and the middle cavity (18), and a second passage (21) is provided between the middle cavity (18) and the discharge cavity (19). The inlet channel (3) of the main valve body (2) and the inlet cavity (17) of the secondary valve body (12) are connected by the first pipe (22). The middle cavity (18) of the secondary valve body (12) is connected to the air chamber (10) of the main valve body (2) through the second pipe (23). The venting cavity (19) of the secondary valve body (12) is connected to the outlet channel (4) of the main valve body (2) through the third pipe (24). Under the combined action of the secondary spring assembly (14) and the medium thrust, the secondary valve core assembly (15) has a first position with the first port (20) open and the second port (21) closed, and a second position with the first port (20) closed and the second port (21) open.

2. The pilot-operated back pressure valve according to claim 1, characterized in that: The sub-valve body (12) is hollow and open at both ends. An upper guide sleeve (25) is sandwiched between the sub-valve body (12) and the sub-valve cover (13). The upper guide sleeve (25) extends into the inner cavity of the sub-valve body (12). The inlet cavity (17) includes a first annular groove (26) arranged circumferentially on the outer surface of the upper guide sleeve (25), a medium inlet (27) arranged on the side of the sub-valve body (12) and connected to the first annular groove (26), and a setting. The upper guide sleeve (25) has an upper chamber (28) at its center, and multiple upper radial holes (29) connecting the first annular groove (26) to the upper chamber (28). An upper sealing ring (30) is provided between the upper guide sleeve (25) and the secondary valve body (12) at positions above and below the first annular groove (26). The first passage (20) is located at the lower end of the upper guide sleeve (25). A base (31) is threadedly connected to the lower end of the inner cavity of the secondary valve body (12). The venting chamber (19) includes a second annular groove (32) arranged circumferentially on the outer surface of the base (31), a venting outlet (33) arranged on the side of the auxiliary valve body (12) and connected to the second annular groove (32), a lower chamber (34) arranged on the base (31), and a plurality of lower radial holes (35) connecting the second annular groove (32) and the lower chamber (34). A lower sealing ring (36) is provided between the base (31) and the auxiliary valve body (12) at positions above and below the second annular groove (32). A secondary valve seat (37) is provided on the base (31) at the upper end of the lower chamber (34). The second passage (21) is arranged on the secondary valve seat (37). The middle cavity (18) is arranged between the upper guide sleeve (25) and the base (31). A medium outlet (38) for connecting the second pipe (23) is provided through the side of the auxiliary valve body (12) at the position corresponding to the middle cavity (18).

3. The pilot-operated back pressure valve according to claim 2, characterized in that: The secondary valve core assembly (15) includes a valve core shaft (39) and a piston rod (40) arranged coaxially. The upper end of the piston rod (40) abuts against the lower end of the valve core shaft (39). A first sealing ring (41) is provided on the outer periphery of the valve core shaft (39), and a second sealing ring (42) is provided on the secondary valve seat (37). When the secondary valve core assembly (15) is in the first position, the lower end of the valve core shaft (39) abuts against the first sealing ring (41) to form a seal. When the secondary valve core assembly (15) is in the second position, the second sealing ring (42) abuts against the inner circular surface of the first passage (20) to form a seal.

4. The pilot-operated back pressure valve according to claim 3, characterized in that: The upper guide sleeve (25) is fitted around the outer circumference of the valve spindle (39), and a pressure-bearing sealing ring (43) is provided between the valve spindle (39) and the upper guide sleeve (25) at a position above the upper chamber (28). The inner circular surface of the first passage (20) is in contact with the outer circular surface of the valve spindle (39), and a plurality of guide grooves (44) for connecting the upper chamber (28) and the middle chamber (18) are provided on the outer circular surface of the valve spindle (39). The base (31) is provided with a piston rod at a position corresponding to the lower end of the lower chamber (34). (40) The piston guide hole (45) extends into the piston rod (40). The outer circular surface of the piston rod (40) is provided with a piston sealing ring (46) for forming a sealing fit with the inner circular surface of the piston guide hole (45). The upper end of the piston rod (40) abuts against the lower end of the valve core shaft (39). The lower end of the piston guide hole (45) is also provided with a balance groove (47) with an inner diameter smaller than that of the piston guide hole (45). The auxiliary valve body (12) and the base (31) are provided with a balance channel (48) for connecting the middle cavity (18) and the balance groove (47).

5. The pilot-operated back pressure valve according to claim 4, characterized in that: The balance groove (47) is equipped with a balance spring (49) for applying an upward spring force to the piston rod (40).

6. The pilot-operated back pressure valve according to claim 4, characterized in that: The balance channel (48) includes a first radial hole (50) extending radially from the outer surface of the base (31) and communicating with the piston guide hole (45); a flow hole (51) extending from the side of the piston rod (40) to the bottom of the piston rod (40) for communicating with the first radial hole (50) and the balance groove (47); an annular guide groove (52) disposed on the inner surface of the sub-valve body (12) and communicating with the outer end of the first radial hole (50); a second radial hole (53) and a third radial hole (54) extending radially from the outer arm of the sub-valve body (12) and communicating with the middle cavity (18) and the annular guide groove (52) respectively; and a vertical hole (55) extending upward from the bottom end of the sub-valve body (12) and communicating with the second radial hole (53) and the third radial hole (54). The outer ends of the second radial hole (53), the third radial hole (54) and the vertical hole (55) are all fitted with plugs (56).

7. The pilot-operated back pressure valve according to claim 3, characterized in that: The base (31) is provided with an installation groove (57) at the upper end of the venting chamber (19). The auxiliary valve seat (37) is embedded in the installation groove (57). The upper end of the auxiliary valve seat (37) is provided with a positioning groove (58) for positioning the second sealing ring (42). The upper end of the installation groove (57) is threaded with a positioning sleeve (59). A pressure ring (60) is sandwiched between the positioning sleeve (59) and the auxiliary valve seat (37). The inner surface of the pressure ring (60) is provided with a pressing flange (61) for pressing the second sealing ring (42) onto the positioning groove (58). An O-ring (62) for forming a sealing fit with the inner surface of the installation groove (57) is also installed on the outer surface of the pressure ring (60).

8. The pilot-operated back pressure valve according to claim 1, characterized in that: The secondary spring assembly (14) includes a guide sleeve (63) installed on the upper end of the secondary valve cover (13), a push rod (64) passing through the guide sleeve (63), a protective cover (65) set on the upper end of the secondary valve cover (13) to cover the upper end of the push rod (64), an upper spring seat (66) and a lower spring seat (67) sleeved on the outer periphery of the push rod (64), and a setter spring (68) sandwiched between the upper spring seat (66) and the lower spring seat (67). The lower end of the push rod (64) is provided with a cone (69) for pressing against the upper end of the secondary valve core assembly (15). The upper end of the upper spring seat (66) abuts against the lower end of the guide sleeve (63), and the lower end of the lower spring seat (67) abuts against the upper end of the cone (69).

9. The pilot-operated back pressure valve according to claim 8, characterized in that: An emergency handle (70) is also hinged to the protective cover (65), and an adjusting nut (71) is threaded to the upper end of the top rod (64). A washer (72) is provided between the emergency handle (70) and the adjusting nut (71).

10. The pilot-operated back pressure valve according to claim 8, characterized in that: It also includes a check valve (73). The first pipe (22) includes a front fitting (74) and a rear fitting (75). The check valve (73) includes a check valve body (76). The inlet end of the check valve body (76) is connected to the inlet channel (3) of the main valve body (2) through the front fitting (74). The outlet end of the check valve body (76) is threadedly connected to a check connector (77). The check connector (77) is connected to the inlet cavity (17) of the auxiliary valve body (12) through the rear fitting (75). A check valve core (78) is axially movable inside the check connector (77). The outer surface of the check valve core (78) is provided with multiple vertically extending flow grooves (79). The inner surface of the check connector (77) near the lower end is also provided with... The valve core (78) is provided with a conical sealing surface (80), and a check sealing ring (81) is installed on the check valve core (78) to form a sealing fit with the conical sealing surface (80) when it moves downward and abuts against the conical sealing surface (80); the lower end of the check joint (77) is also provided with a positioning groove (82), and a hollow filter screen cylinder (83) with an open upper end is embedded in the positioning groove (82); the lower end of the check valve body (76) is provided with a drain port (84), and a drain ball valve (85) is installed at the drain port (84); a positioning spring (86) is sandwiched between the inner end face of the drain ball valve (85) and the filter screen cylinder (83); the outer end of the drain ball valve (85) is connected to the outlet channel (4) of the main valve body (2) through a drain pipe (87).

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