Novel no-load running check valve

Abstract

The utility model discloses a novel no-load running check valve, belongs to the technical field of boiler feed pump self-circulation, and aims to solve the problems of a traditional no-load running check valve. The check valve comprises a first valve body which is in a four-way shape, a lower opening of the first valve body is a main path inlet, an upper opening of the first valve body is a main path outlet, a left opening of the first valve body is an inlet side bypass, a right opening of the first valve body is an outlet side bypass, a throttling sleeve is connected with the inlet side bypass in a sealed mode, and a main valve element rod and the throttling sleeve are matched with a plurality of sealing convex rings through a plurality of bypass sealing flanges. The main path valve clack assembly is in sliding fit with the throttling sleeve and is in sliding sealing with the main valve element rod, the crank seat is in sealing fit with the outlet side bypass, a plurality of crank bodies are hinged to the crank seat, the second spring pushes the main path valve clack assembly leftwards through the crank bodies, and the throttling assembly is arranged in the outlet side bypass. The design of the outlet side bypass is added, the use function of the valve is increased, and the outlet side bypass can be used as a preheating pipeline or a backflow pipeline.

Description

TECHNICAL FIELD

[0001] The utility model belongs to the technical field of boiler feed pump self-circulation, especially relates to a novel air drain check valve. BACKGROUND

[0002] The function of the feed water pump of the thermal power unit is to send the water in the deaerator to the boiler, in order to ensure the safe and effective operation of the water pump, the flow of the water pump must be higher than a certain safety flow under any condition, and the safety flow is the minimum flow of the centrifugal pump. The minimum flow value is obtained by the pump manufacturer through experiment, and is generally 20% to 30% of the rated flow of the pump. When the flow of the water pump is lower than the minimum flow, the temperature of the water pump is increased, the vibration is intensified, cavitation is generated and the like, so that the parts of the pump are damaged. Therefore, the minimum flow protection needs to be designed for the pump. At present, the minimum flow protection has various forms, one of which is to design a self-circulation control protection system, and an air drain check valve is arranged at the pump outlet, the valve can automatically control the opening and closing of the main pipeline and the bypass loop according to the change of the flow, and the normal operation of the pump is ensured.

[0003] At present, the traditional air drain check valve mainly has two structural forms of sliding type and piston type:

[0004] 1, piston type structure, as shown in the drawing. When the main valve flap is opened, the valve flap drives the transmission top rod to contact the bypass valve core rod, so that the valve core rod moves to the right, and the bypass loop is closed. When the main valve flap is closed, the valve flap drives the transmission top rod to separate from the bypass valve core rod, and the valve core rod automatically opens the bypass loop under the action of the piston. Figure 19 The structure has the following disadvantages:

[0005] (1) The bypass loop adopts the piston structure to automatically close. The bypass valve core rod piston and the piston chamber adopt a plurality of O-rings for sealing, the bypass valve core rod is processed with a small hole connected with the bypass outlet, and the pressure below the piston is kept low. If any O-ring is damaged or the small hole of the valve core rod is blocked, the pressure difference between the upper and lower parts of the piston cannot be established, the bypass loop cannot be normally closed, the risk of leakage of the bypass loop is large, and the performance stability is poor.

[0006] (2) In the actual application process, the structure size of the piston and the piston chamber is generally small, so that the size of the O-ring is small, the installation is difficult, the O-ring itself is a vulnerable part, and damage is prone to occur in the installation process. Moreover, the O-rings of the piston and the piston chamber are dynamic seals, the wear intensity is large, the service life of the O-rings is greatly reduced, and finally the bypass loop cannot be normally closed.

[0007]

[0008] ​(3) Product maintenance is difficult. When the product bypass circuit leakage problem occurs, due to too many factors causing the problem, the problem cannot be accurately and quickly located. At the same time, the O-ring may be damaged during disassembly, so that the root cause of the product leakage cannot be determined, and the product maintenance is difficult.

[0009] 2. Sliding structure, such as Figure 20 As shown. When the main road valve disc is opened, the valve disc drives the yoke rod to swing clockwise, so that the bypass small valve disc slides, thereby closing the bypass circuit. When the main road valve disc is closed, the valve disc drives the yoke rod to swing counterclockwise, so that the bypass small valve disc slides again, thereby automatically opening the bypass circuit.

[0010] Such structure has the following shortcomings:

[0011] (1) The switching between the main road and the bypass is completely realized by the swing of the yoke rod, which requires high assembly precision and high technical level of the assembly workers.

[0012] (2) The small valve disc and the bypass valve seat produce sliding friction during each opening and closing process, which is easy to scratch the sealing surface, affect the sealing effect, cause the bypass circuit to leak, and more likely to cause the small valve disc and the bypass valve seat to be directly stuck, causing the main road to be unable to close and the valve to be invalid.

[0013] In summary, a new type of air exhaust check valve with stable bypass circuit performance and convenient installation and maintenance is needed to solve the above problems. Content of the utility model

[0014] The utility model aims at providing a new type of air exhaust check valve to solve the problems of the traditional air exhaust check valve.

[0015] The technical scheme adopted by the utility model is as follows:

[0016] A new type of air exhaust check valve, comprising a first valve body, a valve rod assembly, a main road valve disc assembly, a crank assembly, a throttling assembly and a back pressure adjusting assembly;

[0017] The first valve body is four-way, the lower opening of the first valve body is the main road inlet, the upper opening of the first valve body is the main road outlet, the left opening of the first valve body is the inlet side bypass, and the right opening of the first valve body is the outlet side bypass. The main road inlet and the inlet side bypass are communicated through the left valve cavity, the main road outlet and the outlet side bypass are communicated through the right valve cavity, the left valve cavity and the right valve cavity are communicated through the main road channel, and the first hard alloy sealing surface is stacked on the main road channel.

[0018] The valve stem assembly comprises a main valve core stem and a throttling sleeve, the left part of the throttling sleeve is sealingly connected with the right part of the inlet side bypass, the main valve core stem is slidingly connected with the throttling sleeve, a plurality of sealing convex rings are arranged on the inner hole of the throttling sleeve at intervals, a plurality of bypass sealing convex flanges are arranged on the outer periphery of the main valve core stem at intervals, the plurality of bypass sealing convex flanges and the plurality of sealing convex rings are one-to-one corresponding and abuttingly sealed or separated, when the bypass sealing convex flanges and the corresponding sealing convex rings are separated, the vortex pressure reduction flow channel is formed between the main valve core stem and the throttling sleeve, and the left valve cavity is communicated with the left part of the inlet side bypass through the vortex pressure reduction flow channel;

[0019] The main road valve disc assembly comprises a first main road valve disc, an annular pressure plate, a spring cover and a first spring, a stepped groove is formed on the left end face of the first main road valve disc, the stepped groove is slidingly connected with the right part of the throttling sleeve, a main sealing convex flange is arranged on the right end of the outer periphery of the first main road valve disc, a second hard alloy sealing surface is welded on the main sealing convex flange, the second hard alloy sealing surface and the first hard alloy sealing surface abut to seal or separate, a sliding sink groove is formed on the right end face of the first main road valve disc, the annular pressure plate is coaxially fixed at the slot opening of the sliding sink groove, the spring cover is a left-end-opened cylindrical member, a sliding convex flange is arranged on the left end of the spring cover, the axial thickness of the sliding convex flange is smaller than the depth of the sliding sink groove, the outer periphery of the sliding convex flange is slidingly connected with the side wall of the sliding sink groove, the inner periphery of the annular pressure plate is slidingly connected with the outer periphery of the spring cover, a limiting annular wall is arranged between the stepped groove and the sliding sink groove, the main valve core stem is slidingly and sealingly connected with the inner periphery of the limiting annular wall, the first spring is arranged in the spring cover and sleeved on the main valve core stem, and the two ends of the first spring abut against the limiting annular wall and the right end wall of the spring cover respectively;

[0020] The crank assembly comprises a crank seat, the crank seat is a pipe sleeve-shaped member, a plurality of connecting ears are arranged on the left end of the crank seat, one end of each of a plurality of crank bodies is hingedly connected with one of the connecting ears, the crank seat is sealingly connected with the outlet side bypass, and the other end of each of the plurality of crank bodies abuts against the right end wall of the spring cover;

[0021] The large-diameter end of the bypass reducing flange is connected with the pipe body of the outlet side bypass, the bypass reducing flange is sealingly connected with the crank seat, and the throttling assembly is arranged on the inner hole diameter of the bypass reducing flange;

[0022] The spring seat, the second spring and the throttling assembly are sequentially abutted from left to right, the spring seat is bowl-shaped, the mouth end of the spring seat is arranged towards left and abuts against the right side of the plurality of crank bodies, a connecting screw hole and a plurality of fourth flow-through holes are arranged on the bottom of the bowl of the spring seat, the main valve core stem is threadedly connected with the connecting screw hole, the second spring is sleeved on the main valve core stem, a third positioning hole is formed on the left end face of the first throttling ring, and the main valve core stem is slidingly connected with the third positioning hole;

[0023] The back pressure adjusting assembly is arranged at the left end of the diameter of the inlet side bypass.

[0024] Further, the valve rod assembly further comprises a locking sleeve, the inner hole of the throttling sleeve is composed of a throttling hole, a balance hole and a first positioning hole coaxially connected in sequence from left to right, a plurality of sealing convex rings are arranged at intervals on the side wall of the throttling hole, a plurality of first flow-through holes are arranged circumferentially on the side wall of the balance hole, the locking sleeve is fixed at the left end of the throttling sleeve, the locking sleeve closes the left end opening of the throttling sleeve, the locking sleeve is provided with a second positioning hole and a plurality of second flow-through holes, the main valve core rod comprises a second positioning section, a sealing section, a balance section, a first positioning section, a connecting section and a third positioning section coaxially connected in sequence from left to right, a plurality of bypass sealing flanges are arranged at intervals on the sealing section, the second positioning section is in sliding fit with the second positioning hole, the annular cavity is formed between the outer periphery of the balance section and the side wall of the balance hole, the left part of the first positioning section is in sliding fit with the first positioning hole, and the annular cavity is communicated with the left valve cavity through the plurality of first flow-through holes.

[0025] Further, the stepped groove is composed of a guide groove, a flow-through groove and a balance groove coaxially connected in sequence from left to right, the diameter of the guide groove is smaller than that of the flow-through groove and the balance groove, the side wall of the guide groove is in sliding fit with the outer periphery of the throttling sleeve, the first positioning section is in sliding sealing fit with the inner periphery of the limiting annular wall, a plurality of third flow-through holes are arranged circumferentially on the side wall of the flow-through groove, the left valve cavity is communicated with the balance groove through the plurality of third flow-through holes and the flow-through groove in sequence, and the first spring sleeve is connected to the first positioning section.

[0026] Further, a concave stop opening is formed on the right end face of the pipe body of the outlet side bypass, the concave stop opening is coaxial with the outlet side bypass, the right end of the crank seat is provided with a positioning flange, the positioning flange is pressed in the concave stop opening by the bypass reducing flange, and the positioning flange is in stop fit with the concave stop opening.

[0027] Further, the throttling assembly comprises a first throttling ring and a plurality of throttling hole plates, the first throttling ring and the plurality of throttling hole plates are arranged in sequence from left to right on the inner hole diameter of the bypass reducing flange, axial gaps are arranged between the first throttling ring and the adjacent throttling hole plate and between the adjacent two throttling hole plates, and a plurality of fifth flow-through holes are formed in the first throttling ring.

[0028] Further, the edge of the throttling hole plate is provided with a left protruding separation ring structure, and the throttling hole plate is abutted with the left adjacent throttling hole plate or throttling ring through the separation ring structure.

[0029] Further, the inner hole of the bypass reducing flange is a stepped hole, a first snap spring is arranged in the inner hole of the bypass reducing flange, and the first throttling ring and the plurality of throttling hole plates are axially limited by the snap spring and the inner hole step of the bypass reducing flange.

[0030] Further, the back pressure adjusting assembly comprises a connecting seat, a sealing plate, a third spring and an adjusting cover, the connecting seat is arranged at the left end of the passage diameter of the inlet side bypass, the connecting seat is a sleeve-shaped component, the connecting seat is provided with a right end wall, the sixth flow-through hole is arranged on the right end wall of the connecting seat, the inner periphery of the connecting seat is threadedly connected with the outer periphery of the adjusting cover, the adjusting cover is provided with a plurality of seventh flow-through holes, and the sealing plate is pressed on the right end wall of the connecting seat by the third spring to close the fifth flow-through hole.

[0031] Further, the inlet side bypass is a stepped hole, the second snap spring is arranged in the inlet side bypass, and the back pressure adjusting assembly is axially limited by the stepped hole of the inner hole of the inlet side bypass.

[0032] Compared with the prior art, the utility model has the beneficial effects that:

[0033] 1. The novel air discharge check valve increases the use function of the valve by designing the outlet side bypass, a bypass pipeline is additionally arranged, the bypass pipeline can be used as a preheating pipeline or a return pipeline, the bypass flange can be replaced by a blind plate according to the need, the function of the valve is consistent with that of the traditional air discharge check valve.

[0034] 2. The novel air discharge check valve realizes the opening and closing of the bypass circuit by the mechanical property of the second spring, the performance is more stable, the first spring is arranged in the main road valve piece assembly, the inlet side bypass leakage caused by the working condition fluctuation is overcome, and the sealing performance of the inlet side bypass is improved.

[0035] 3. The novel air discharge check valve reduces the pressure difference of the two ends of the valve rod assembly by designing the back pressure adjusting assembly, reduces the occurrence of the cavitation phenomenon, thereby better protecting the valve rod assembly and improving the performance stability and service life of the inlet side bypass.

[0036] 4. The main function of the novel air discharge check valve is realized by the spring force, the machining precision and assembly requirement are low, the performance is more stable, all the internal parts are installed from one side, during the maintenance process, after the bypass reducing flange is disassembled, all the internal parts can be disassembled in sequence, and the installation and maintenance are convenient. BRIEF DESCRIPTION OF DRAWINGS

[0037] Figure 1 It is a structure schematic view of the novel air discharge check valve of the utility model;

[0038] Figure 2 It is a structure schematic view of the first valve body;

[0039] Figure 3 It is a structure schematic view of the valve rod assembly;

[0040] Figure 4 It is a structure schematic view of the throttling sleeve;

[0041] Figure 5 is a structural schematic diagram of the main valve core rod;

[0042] Figure 6 is a structural schematic diagram of the locking sleeve;

[0043] Figure 7 is a structural schematic diagram of the main path valve clack assembly;

[0044] Figure 8 is a structural schematic diagram of the first main path valve clack;

[0045] Figure 9 is a structural schematic diagram of the spring cover;

[0046] Figure 10 is a cooperation schematic diagram of the crank assembly and the throttling assembly;

[0047] Figure 11 is a structural schematic diagram of the crank assembly;

[0048] Figure 12 is a left view of Figure 11 ;

[0049] Figure 13 is a structural schematic diagram of the spring seat;

[0050] Figure 14 is a K view of Figure 13 ;

[0051] Figure 15 is a cooperation schematic diagram of the throttling assembly and the bypass variable diameter flange;

[0052] Figure 16 is a cooperation schematic diagram of the back pressure adjusting assembly and the first valve body;

[0053] Figure 17 is a connection schematic diagram of the use method of the new air drain check valve in the second embodiment of the utility model;

[0054] Figure 18 is a connection schematic diagram of the use method of the new air drain check valve in the third embodiment of the utility model;

[0055] Figure 19 is a structural schematic diagram of a traditional piston type air drain check valve;

[0056] Figure 20 is a structural schematic diagram of a traditional sliding type air drain check valve.

[0057] 1. first valve body, 2. valve stem assembly, 3. main path valve disc assembly, 4. back pressure adjusting assembly, 5. crank assembly, 6. throttling assembly, 7. bypass variable flange, 8. main path inlet, 9. main path outlet, 10. inlet side bypass, 11. outlet side bypass, 12. left valve cavity, 13. main path channel, 14. right valve cavity, 15. first hard alloy sealing surface, 16. concave stop, 17. locking sleeve, 18. throttling sleeve, 19. main valve core stem, 20. throttling hole, 21. sealing convex ring, 22. first flow-through hole, 23. balance hole, 24. first positioning hole, 25. second positioning section, 26. sealing section, 27. bypass sealing flange, 28. balance section, 29. first positioning section, 30. connecting section, 31. third positioning section, 32. second positioning hole, 33. second flow-through hole, 34. first main path valve disc, 35. annular pressing plate, 36. first spring, 37. spring cover, 38. guide groove, 39. flow-through groove, 40. balance groove, 41. third flow-through hole, 42. main sealing flange, 43. second hard alloy sealing surface, 44. limiting annular wall, 45. sliding sunken groove, 46. sliding flange, 47. fourth positioning hole, 48. crank seat, 49. spring seat, 50. second spring, 51. sealing ring, 52. crank body, 53. positioning flange, 54. bowl bottom, 55. connecting screw hole, 56. fourth flow-through hole, 57. mouth edge end, 58. first throttling ring, 59. throttling hole plate, 60. fifth flow-through hole, 61. third positioning hole, 62. spacer ring structure, 63. first clasp spring, 64. connecting seat, 65. sealing plate, 66. third spring, 67. adjusting cover, 68. sixth flow-through hole, 69. second clasp spring, 70. second valve body, 71. transmission top rod, 72. second main path valve disc, 73. piston chamber, 74. piston, 75. throttling cylinder, 76. bypass valve core stem, 77. third valve body, 78. third main path valve disc, 79. yoke rod, 80. small valve disc, 81. bypass valve seat, 82. second throttling ring, 100. empty discharge check valve, 200. deaerator, 300. boiler, 400. water pump, 410. first main pipeline, 500. first shut-off valve, 510. second main pipeline, 600. second shut-off valve, 610. second bypass pipeline, 710. first bypass pipeline. DETAILED DESCRIPTION

[0058] In order to make the purpose, technical scheme and advantages of the utility model more clear and obvious, the following will describe the utility model through specific embodiments shown in the drawings. However, it should be understood that these descriptions are only exemplary and not to limit the scope of the utility model. In addition, in the following description, the description of the known structure and technology is omitted to avoid unnecessary confusion of the concept of the utility model.

[0059] The connection mentioned in the utility model is divided into fixed connection and detachable connection, the fixed connection is namely the non-detachable connection including but not limited to the edge folding connection, rivet connection, cementation connection and welding connection and other conventional fixed connection modes, the detachable connection includes but is not limited to the bolt connection, buckle connection, pin connection and hinge connection and other conventional detachable modes, when the specific connection mode is not limited, at least one connection mode is found in the existing connection mode to realize the function, and the person skilled in the art can select by himself according to the need.For example: the fixed connection selects the welding connection, and the detachable connection selects the bolt connection.

[0060] The utility model will be further explained in detail in combination with the drawings, and the following examples are the explanation of the utility model, and the utility model is not limited to the following examples.

[0061] Example one: as shown in Figures 1-16 、 Figure 19 、 Figure 20 A novel air discharge check valve, including first valve body 1, valve rod assembly 2, main road valve clapper assembly 3, crank assembly 5, throttling assembly 6 and back pressure adjustment assembly 4;

[0062] The first valve body 1 is four-way, and the lower opening of the first valve body 1 is the main road inlet 8, the upper opening of the first valve body 1 is the main road outlet 9, the left opening of the first valve body 1 is the inlet side bypass 10, and the right opening of the first valve body 1 is the outlet side bypass 11, the main road inlet 8 and the inlet side bypass 10 are communicated through the left valve cavity 12, the main road outlet 9 and the outlet side bypass 11 are communicated through the right valve cavity 14, the left valve cavity 12 and the right valve cavity 14 are communicated through the main road passage 13, and the first hard alloy sealing surface 15 is stacked on the main road passage 13;

[0063] The valve rod assembly 2 includes the main valve core rod 19 and the throttling sleeve 18, the left part of the throttling sleeve 18 is sealingly connected with the right part of the inlet side bypass 10, the right part of the throttling sleeve 18 extends into the left valve cavity 12, the main valve core rod 19 is slidingly connected with the throttling sleeve 18, a plurality of sealing convex rings 21 are arranged on the inner hole of the throttling sleeve 18, a plurality of bypass sealing flanges 27 are arranged on the outer periphery of the main valve core rod 19, the outer periphery of the bypass sealing flange 27 is not in contact with the side wall of the throttling hole 20, the outer periphery of the sealing convex ring 21 is also not in contact with the sealing section 26, but the plurality of bypass sealing flanges 27 and the plurality of sealing convex rings 21 are in one-to-one correspondence and abut or separate, when the bypass sealing flange 27 and the corresponding sealing convex ring 21 are separated, the vortex pressure reduction flow channel is formed between the main valve core rod 19 and the throttling sleeve 18, and the left valve cavity 12 is communicated with the left part of the inlet side bypass 10 through the vortex pressure reduction flow channel;

[0064] The main road valve disc assembly 3 comprises a first main road valve disc 34, an annular pressing plate 35, a spring cover 37 and a first spring 36. The first main road valve disc 34 is sleeved on the main valve core rod 19. A stepped groove is formed on the left end face of the first main road valve disc 34. The stepped groove is in sliding fit with the right part of the outer periphery of the throttling sleeve 18. A main sealing flange 42 is arranged on the outer periphery of the right end of the first main road valve disc 34. A second hard alloy sealing surface 43 is stacked on the main sealing flange 42. The second hard alloy sealing surface 43 is in sealing abutment or separation with the first hard alloy sealing surface 15. A sliding sink groove 45 is formed on the right end face of the first main road valve disc 34. The annular pressing plate 35 is coaxially fixed at the slot opening of the sliding sink groove 45. The spring cover 37 is a cylindrical member with an open left end. A sliding flange 46 is arranged on the left end of the spring cover 37. The axial thickness of the sliding flange 46 is smaller than the depth of the sliding sink groove 45. The outer periphery of the sliding flange 46 is in sliding fit with the side wall of the sliding sink groove 45. The inner periphery of the annular pressing plate 35 is in sliding fit with the outer periphery of the spring cover 37. The bottom of the sliding sink groove 45 and the annular pressing plate 35 axially limit the sliding flange 46. A limiting annular wall 44 is arranged between the stepped groove and the sliding sink groove 45. The limiting annular wall 44 is integrally formed with the first main road valve disc 34. A fourth positioning hole 47 is arranged on the right end wall of the spring cover 37. The main valve core rod 19 passes through the inner periphery of the limiting annular wall 44 and the fourth positioning hole 47. The main valve core rod 19 is in sliding fit with the fourth positioning hole 47. The main valve core rod 19 is in sliding sealing fit with the inner periphery of the limiting annular wall 44 through a sealing ring 51. The first spring 36 is arranged in the spring cover 37. The first spring 36 is sleeved on the main valve core rod 19. The two ends of the first spring 36 are in abutment with the limiting annular wall 44 and the right end wall of the spring cover 37 respectively.

[0065] The crank assembly 5 comprises a crank seat 48. The crank seat 48 is a pipe sleeve-shaped member. A plurality of connecting ears are arranged on the left end of the crank seat 48. One end of each of a plurality of crank bodies 52 is hingedly connected with one of the connecting ears. The main valve core rod 19 passes through the plurality of crank bodies 52. The crank seat 48 is in sealing fit with the outlet side bypass 11 through an O-ring. The other end of each of the plurality of crank bodies 52 is in abutment with the right end wall of the spring cover 37.

[0066] The large-diameter end of the bypass reducing flange 7 is connected with the pipe body of the outlet side bypass 11. The bypass reducing flange 7 is in sealing fit with the crank seat 48 through an O-ring. The throttling assembly 6 is arranged on the inner hole diameter of the bypass reducing flange 7.

[0067] The spring seat 49, the second spring 50, and the throttling assembly 6 abut against each other from left to right. The spring seat 49 is bowl-shaped, with the rim 57 of the spring seat 49 facing left. The rim 57 abuts against the right side of several crank bodies 52. The bottom 54 of the bowl of the spring seat 49 is provided with a connecting screw hole 55 and several fourth flow holes 56. The main valve core rod 19 is threadedly engaged with the connecting screw hole 55. The second spring 50 is sleeved on the main valve core rod 19. The left end face of the first throttling ring 58 is provided with a third positioning hole 61. The main valve core rod 19 is slidably engaged with the third positioning hole 61.

[0068] The back pressure adjustment component 4 is located at the left end of the inlet bypass 10.

[0069] Currently, traditional air vent check valves mainly come in two structural forms: sliding air vent check valves and piston air vent check valves.

[0070] 1. Piston-type empty drain check valve, such as Figure 19 As shown, the valve includes a second valve body 70. The right opening of the second valve body 70 is a medium inlet channel, and the left opening is a medium outlet channel. The medium inlet channel and the medium outlet channel of the piston-type air vent check valve form a coaxial main channel. The second main valve disc 72 is slidably disposed in the main channel of the piston-type air vent check valve and abuts against and seals or separates from the valve seat disposed in the medium outlet channel of the second valve body 70. The upper side of the second valve body 70 is a bypass circuit. The bypass circuit of the second valve body 70 is provided with a matching throttle cylinder 75 and a bypass valve core rod 76. Below the throttle cylinder 75 is a piston chamber 73. The piston 74 is slidably engaged with the piston chamber 73. The bypass valve core rod 76 is connected to the piston 74. When the second main valve disc 72 is opened, the second main valve disc 72 drives the transmission push rod 71 to rotate clockwise. The transmission push rod 71 pushes the bypass valve core rod 76 upward through the piston 74, thereby closing the bypass circuit of the piston-type air vent check valve. When the second main valve disc 72 is closed, the second main valve disc 72 drives the transmission push rod 71 to rotate counterclockwise, and the bypass valve core rod 76 automatically opens the bypass circuit of the piston-type empty check valve under the action of the piston 74.

[0071] This type of structure has the following shortcomings:

[0072] a. The bypass circuit uses a piston 74 structure for automatic closure. The bypass valve stem 76, piston 74, and piston chamber 73 are sealed with multiple O-rings. A through-hole is machined along the axis of the bypass valve stem 76. The two ends of the bypass circuit of the piston-type air vent check valve are connected through this through-hole to maintain a low pressure below piston 74. If any O-ring in the bypass valve stem 76, piston 74, or piston chamber 73 is damaged, or if the through-hole is blocked, a pressure differential cannot be established above and below piston 74. This prevents the bypass circuit of the piston-type air vent check valve from closing properly, resulting in a high risk of leakage and poor performance stability.

[0073] b. In actual use, the structure size of the piston 74 and the piston chamber 73 is generally small, resulting in small size of the O-ring for sealing, which is difficult to install, and the O-ring itself is a consumable part, which is easily damaged during installation. Moreover, the O-ring for the piston 74 and the piston chamber 73 is a dynamic seal, which has a large wear intensity and greatly reduces the service life of the O-ring, ultimately resulting in the failure of the bypass circuit to normally close.

[0074] c. Product maintenance is difficult. When leakage occurs in the bypass circuit of the piston type air drain check valve, it is difficult to accurately and quickly locate the leakage cause due to too many factors causing the leakage. Meanwhile, the O-ring can be damaged during disassembly, which makes it impossible to determine the root cause of the product leakage, greatly increasing the difficulty of product maintenance.

[0075] 2. The sliding type air drain check valve, as shown in Figure 20 The third valve body 77 has a medium inlet passage on the right and a medium outlet passage on the left. The medium inlet passage and the medium outlet passage of the sliding type air drain check valve form a coaxial main flow passage. The third main valve disc 78 is slidably arranged in the main flow passage of the sliding type air drain check valve and is in sealing abutment or separation with the valve seat arranged in the medium outlet passage of the third valve body 77. The upper side of the third valve body 77 is a bypass circuit. When the third main valve disc 78 is opened, the third main valve disc 78 drives the yoke rod 79 to swing clockwise, causing the bypass valve disc 80 to slide upward and thereby closing the bypass circuit of the sliding type air drain check valve. When the third main valve disc 78 is closed, the valve disc drives the yoke rod 79 to swing counterclockwise, causing the small valve disc 80 to slide downward and thereby automatically opening the bypass circuit of the sliding type air drain check valve.

[0076] Such structure has the following disadvantages:

[0077] a. The switching between the main flow passage and the bypass circuit of the sliding type air drain check valve completely relies on the swinging of the yoke rod 79, which requires high assembly precision and high technical level of the assembly workers.

[0078] b. During each opening and closing process, the small valve disc 80 and the bypass valve seat 81 produce sliding friction, which easily scratches the sealing surface, affects the sealing effect, and causes leakage of the bypass circuit of the sliding type air drain check valve. Moreover, the small valve disc 80 and the bypass valve seat 81 can be stuck, causing the main flow passage of the sliding type air drain check valve to be unable to close, and the entire valve to fail.

[0079] The utility model discloses a novel air exhaust check valve 100 has dual bypass structure, and the main road valve clack assembly 3 is equipped with first spring 36 and spring cover 37, and first spring 36 can compress in a certain range, and the valve opens initial stage, and the spring force of first spring 36 is greater than the elastic force of second spring 50 through several crank bodies 52 transmission, under the action of medium force, second spring 50 is compressed first, because the sliding stroke of main road valve clack assembly 3 is far greater than the sliding stroke of main valve core stem 19, when main road valve clack assembly 3 slides to main road passage 13, import side bypass 10 has been completely closed, as shown in the state, after second spring 50 cannot continue to compress through limiting, main road valve clack assembly 3 has not reached full opening position at this time, will continue to compress first spring 36, until opening to full stroke. Figure 1 When switching the working condition, the first spring 36 preferentially rebounds, the second spring 50 continues to rebound, and the plurality of crank bodies 52 push the main road valve clack assembly 3 to slide leftwards, so that the second hard alloy sealing surface 43 abuts against and seals the first hard alloy sealing surface 15, the spring seat 49 drives the main valve core stem 19 to slide leftwards, and the plurality of bypass sealing flanges 27 and the plurality of sealing convex rings 21 are separated one by one, and the import side bypass 10 is opened.

[0080] When the main road valve clack assembly 3 is in the full opening position, under the condition that the operating condition fluctuates, the first spring 36 preferentially rebounds, the second spring 50 is stationary, and the import side bypass 10 is still in the closed state, so that the import side bypass leakage caused by the fluctuation of the working condition is overcome, and the sealing performance of the import side bypass is improved.

[0081] The valve stem assembly 2 further includes a locking sleeve 17, and the inner hole of the throttling sleeve 18 is composed of a throttling hole 20, a balance hole 23 and a first positioning hole 24 coaxially connected in sequence from left to right, the plurality of sealing convex rings 21 are arranged at intervals on the side wall of the throttling hole 20, a plurality of first flow-through holes 22 are arranged on the side wall of the balance hole 23, the locking sleeve 17 is fixed to the left end of the throttling sleeve 18, the locking sleeve 17 closes the left end opening of the throttling sleeve 18, the locking sleeve 17 is provided with a second positioning hole 32 and a plurality of second flow-through holes 33, the main valve core stem 19 includes a second positioning section 25, a sealing section 26, a balance section 28, a first positioning section 29, a connecting section 30 and a third positioning section 31 coaxially connected in sequence from left to right, the plurality of bypass sealing flanges 27 are arranged at intervals on the sealing section 26, the second positioning section 25 is in sliding fit with the second positioning hole 32, an annular cavity is formed between the outer periphery of the balance section 28 and the side wall of the balance hole 23, the left part of the first positioning section 29 is in sliding fit with the first positioning hole 24, and the annular cavity is in communication with the left valve cavity 12 through the plurality of first flow-through holes 22.

[0082] The stepped groove is composed of the guide groove 38, the flow passage 39 and the balance groove 40 coaxially connected in sequence from left to right, the diameter of the guide groove 38 is smaller than that of the flow passage 39 and the balance groove 40, the side wall of the guide groove 38 is in sliding fit with the outer circumferential right part of the throttling sleeve 18, the first positioning section 29 is in sliding sealing fit with the inner circumferential of the limiting annular wall 44, there is a gap between the side wall of the flow passage 39 and the balance groove 40 and the outer circumferential of the first positioning section 29, a plurality of third flow-through holes 41 are circumferentially arranged on the side wall of the flow passage 39, the left valve cavity 12 is communicated with the balance groove 40 through the plurality of third flow-through holes 41 and the flow passage 39 in sequence, so as to keep the pressure of the balance groove 40 consistent with that of the left valve cavity 12, the right part of the first positioning section 29 passes through the inner circumferential of the limiting annular wall 44 and the fourth positioning hole 47, the first positioning section 29 is in sliding fit with the fourth positioning hole 47, and the first spring 36 is sleeved on the first positioning section 29.

[0083] The recessed notch 16 is coaxial with the outlet side bypass 11, the right end of the crank base 48 is provided with a positioning flange 53, the positioning flange 53 is pressed in the recessed notch 16 by the bypass reducing flange 7, and the positioning flange 53 is in notch fit with the recessed notch 16.

[0084] The throttling assembly 6 comprises the first throttling ring 58 and a plurality of throttling orifice plates 59, which are arranged in sequence from left to right on the inner hole diameter of the bypass reducing flange 7, axial gaps are arranged between the first throttling ring 58 and the adjacent throttling orifice plate 59 and between the adjacent two throttling orifice plates 59, and a plurality of fifth flow-through holes 60 are arranged on the first throttling ring 58.

[0085] The edge of the throttling orifice plate 59 is provided with a left protruding partition ring structure 62, the throttling orifice plate 59 is in abutment with the left adjacent throttling orifice plate 59 or throttling ring through the partition ring structure 62, so that a gap is formed between the adjacent two throttling orifice plates 59 and a gap is also formed between the throttling ring and the adjacent throttling orifice plate 59, so as to facilitate the medium to pass through the throttling holes 20 on the throttling ring and the plurality of throttling orifice plates 59 in sequence.

[0086] The inner hole of the bypass reducing flange 7 is a stepped hole, the first throttling ring 58 and the plurality of throttling orifice plates 59 are axially limited through the snap spring and the inner hole step of the bypass reducing flange 7.

[0087] The back pressure adjusting assembly 4 comprises a connecting seat 64, a sealing plate 65, a third spring 66 and an adjusting cover 67, the connecting seat 64 is arranged at the left end of the passage diameter of the inlet side bypass 10, the connecting seat 64 is a sleeve-shaped component, the connecting seat 64 is provided with a right end wall, the sixth flow-through hole 68 is arranged on the right end wall of the connecting seat 64, the inner periphery of the connecting seat 64 is threadedly connected with the outer periphery of the adjusting cover 67, the adjusting cover 67 is provided with a plurality of seventh flow-through holes, the sealing plate 65 is pressed on the right end wall of the connecting seat 64 by the third spring 66, so as to close the fifth flow-through hole 60, the inlet side bypass 10 is a stepped hole, the second snap spring 69 is arranged in the inlet side bypass 10, and the back pressure adjusting assembly 4 is axially limited by the second snap spring 69 and the inner hole step of the inlet side bypass 10.

[0088] The connecting seat 64 and the adjusting cover 67 are threadedly connected, the adjusting cover 67 compresses the third spring 66, and the sealing plate 65 can close the fifth flow-through hole 60 under the spring force of the third spring 66. By adjusting the relative position of the connecting seat 64 and the adjusting cover 67, the minimum pressure required to open the sealing plate 65 can be controlled, a pressure cavity is formed before the sealing plate 65, thereby reducing the pressure difference between the two ends of the valve stem assembly 2, reducing the occurrence of cavitation, thereby better protecting the valve stem assembly 2 and prolonging the service life of the valve.

[0089] The novel air discharge check valve is provided with the outlet side bypass 11, the use function of the valve is improved, compared with the traditional air discharge check valve, a bypass pipeline is additionally arranged, can be used as a preheating pipeline or a reflux pipeline, and the bypass flange can be replaced by a blind plate according to needs, so that the function of the valve is consistent with that of the traditional air discharge check valve.

[0090] The novel air discharge check valve realizes opening and closing of the bypass circuit through the mechanical property of the second spring 50, and the performance is more stable, the main path valve disc assembly 3 is provided with the first spring 36, inlet side bypass leakage caused by working condition fluctuation is overcome, and the sealing performance of the inlet side bypass is improved.

[0091] The novel air discharge check valve is provided with the back pressure adjusting assembly 4, the pressure difference between the two ends of the valve stem assembly 2 is reduced, the occurrence of cavitation is reduced, thereby better protecting the valve stem assembly 2 and improving the performance stability and service life of the inlet side bypass 10.

[0092] The main function of the novel air discharge check valve is realized through spring force, the machining precision and assembly requirement are low, the performance is more stable, all internal parts are installed from one side, during maintenance, only the bypass reducing flange 7 needs to be disassembled, then all internal parts can be disassembled in sequence, and installation and maintenance are facilitated.

[0093] Embodiment two: as Figures 1-17As shown, the new emptying check valve is an emptying check valve 100, for which, the deaerator 200 can be connected with the main inlet 8 through a first main pipeline 410, the water pump 400 is arranged on the first main pipeline 410, the main outlet 9 is connected with the boiler 300 through a second main pipeline 510, the first shutoff valve 500 is arranged on the second main pipeline 510, the inlet side bypass 10 is connected with the deaerator 200 through a first bypass pipeline 710, the outlet side bypass 11 is connected with the boiler 300 through a second bypass pipeline 610, the second shutoff valve 600 is arranged on the second bypass pipeline 610, and the second bypass pipeline 610 is used as a preheating pipeline.

[0094] In the starting stage of the system, the first shutoff valve 500 is closed, and the second shutoff valve 600 is opened, at this time, after the main valve disc assembly 3 is opened, the medium enters the boiler 300 from the outlet side bypass 11, and is subjected to multi-stage pressure reduction through the throttling assembly 6, so that the medium can enter the boiler 300 at a small pressure and flow rate, thereby playing a preheating role, ensuring normal operation of the boiler 300, and prolonging the service life of the boiler.

[0095] When the normal starting condition is reached, the first shutoff valve 500 is opened, and the second shutoff valve 600 is closed, at this time, after the main valve disc assembly 3 is opened, the medium enters the boiler 300 from the second main pipeline 510 at normal working condition parameters.

[0096] When the unit is operated at full load, under the action of the medium force, the main valve disc assembly 3 slides to the right to open and drives the plurality of crank bodies 52 to rotate, the spring seat 49 is pushed to the right, and the main valve core rod 19 slides to the right due to the connection between the spring seat 49 and the main valve core rod 19, at this time, the plurality of bypass sealing flanges 27 and the plurality of sealing convex rings 21 are in one-to-one correspondence and abut to seal, the inlet side bypass 10 is closed, and the medium enters the boiler 300 from the second main pipeline 510 or the second bypass pipeline 610.

[0097] When the unit is operated at low load, the medium action force decreases, the main valve core rod 19 slides to the left under the action of the spring force of the second spring 50, at this time, the inlet side bypass 10 is opened; the spring seat 49 drives the plurality of crank bodies 52 to rotate, and the main valve disc assembly 3 is closed, and the medium only flows back to the deaerator 200 after multi-stage pressure reduction in the vortex pressure reduction flow channel.

[0098] Example Three: as Figures 1-16 , Figure 18As shown, the new emptying check valve is an emptying check valve 100, for which, the deaerator 200 can be connected with the main inlet 8 through a first main pipeline 410, the first main pipeline 410 is provided with a water pump 400, the main outlet 9 is connected with the boiler 300 through a second main pipeline 510, the second main pipeline 510 is provided with a first shutoff valve 500, the inlet side bypass 10 is connected with the deaerator 200 through a first bypass pipeline 710, the outlet side bypass 11 is connected with the deaerator 200 through a second bypass pipeline 610, the second bypass pipeline 610 is provided with a second shutoff valve 600, and the second bypass pipeline 610 is used as a return pipeline.

[0099] When the system is in normal operation, the first shutoff valve 500 is opened, and the second shutoff valve 600 is closed, at this time, after the main valve disc assembly 3 is opened, the medium enters the boiler 300 from the second main pipeline 510 at normal working condition parameters.

[0100] When an emergency working condition occurs, the parameter of the water pump 400 cannot be rapidly reduced to a preset parameter, at this time, the inlet side bypass 10 cannot be opened, the first shutoff valve 500 is closed, and the second shutoff valve 600 is opened, so that the medium returns to the deaerator 200 after multi-stage pressure reduction through the throttling assembly 6.

[0101] When the unit is in full load operation, under the action of the medium force, the main valve disc assembly 3 slides to the right and is opened, a plurality of crank bodies 52 are driven to rotate, the spring seat 49 is pushed to the right, the main valve core rod 19 is slid to the right through the connection of the spring seat 49 and the main valve core rod 19, at this time, a plurality of bypass sealing flanges 27 and a plurality of sealing convex rings 21 are in one-to-one correspondence and abut to seal, the inlet side bypass 10 is closed, and the medium enters the boiler 300 from the second main pipeline 510 or the second bypass pipeline 610. Under an emergency working condition, the medium returns to the deaerator 200 from the second bypass pipeline 610.

[0102] When the unit is in low load operation, the medium action force is reduced, the main valve core rod 19 slides to the left under the action of the spring force of the second spring 50, at this time, the inlet side bypass 10 is opened; the spring seat 19 is moved to the left, the crank body 52 is driven to rotate by the spring seat 49, the main valve disc assembly 3 is closed, and the medium returns to the deaerator 200 after multi-stage pressure reduction through the vortex pressure reduction flow channel.

[0103] The above embodiment is only an exemplary description of the utility model, and does not limit the protection range thereof, and the person skilled in the art can also change it locally, as long as it does not exceed the spirit and essence of the utility model, and is within the protection range of the utility model.

Claims

1. A new type of air vent check valve characterized by: The application relates to a valve body, which comprises a first valve body (1), a valve rod assembly (2), a main path valve disc assembly (3), a crank assembly (5), a throttling assembly (6) and a back pressure adjusting assembly (4); The first valve body (1) is four-way, the lower opening of the first valve body (1) is a main path inlet (8), the upper opening of the first valve body (1) is a main path outlet (9), the left opening of the first valve body (1) is an inlet side bypass (10), the right opening of the first valve body (1) is an outlet side bypass (11), the main path inlet (8) and the inlet side bypass (10) are communicated through a left valve cavity (12), the main path outlet (9) and the outlet side bypass (11) are communicated through a right valve cavity (14), the left valve cavity (12) and the right valve cavity (14) are communicated through a main path channel (13), and a first hard alloy sealing surface (15) is stacked on the main path channel (13); The valve rod assembly (2) comprises a main valve core rod (19) and a throttling sleeve (18), the left part of the throttling sleeve (18) is sealingly connected with the right part of the inlet side bypass (10), the main valve core rod (19) is slidingly matched with the throttling sleeve (18), a plurality of sealing convex rings (21) are arranged on the inner hole of the throttling sleeve (18) at intervals, a plurality of bypass sealing convex flanges (27) are arranged on the outer periphery of the main valve core rod (19) at intervals, the plurality of bypass sealing convex flanges (27) and the plurality of sealing convex rings (21) are one-to-one corresponding and abutting or separated, when the bypass sealing convex flanges (27) and the corresponding sealing convex rings (21) are separated, a vortex pressure reduction flow channel is formed between the main valve core rod (19) and the throttling sleeve (18), and the left valve cavity (12) is communicated with the left part of the inlet side bypass (10) through the vortex pressure reduction flow channel; The main road valve disc assembly (3) comprises a first main road valve disc (34), an annular pressing plate (35), a spring cover (37) and a first spring (36), a stepped groove is formed on the left end face of the first main road valve disc (34), the stepped groove is in sliding fit with the right part of the outer periphery of the throttling sleeve (18), a main sealing flange (42) is arranged on the right end of the outer periphery of the first main road valve disc (34), a second hard alloy sealing surface (43) is welded on the main sealing flange (42), the second hard alloy sealing surface (43) is in sealing or separating fit with the first hard alloy sealing surface (15), a sliding sink groove (45) is formed on the right end face of the first main road valve disc (34), the annular pressing plate (35) is coaxially fixed at the slot opening of the sliding sink groove (45), the spring cover (37) is a cylindrical member with an open left end, a sliding flange (46) is arranged on the left end of the spring cover (37), the axial thickness of the sliding flange (46) is smaller than the depth of the sliding sink groove (45), the outer periphery of the sliding flange (46) is in sliding fit with the side wall of the sliding sink groove (45), the inner periphery of the annular pressing plate (35) is in sliding fit with the outer periphery of the spring cover (37), a limiting annular wall (44) is arranged between the stepped groove and the sliding sink groove (45), the main valve core rod (19) is in sliding sealing fit with the inner periphery of the limiting annular wall (44), the first spring (36) is arranged in the spring cover (37), the first spring (36) is sleeved on the main valve core rod (19), the two ends of the first spring (36) are respectively in abutting fit with the limiting annular wall (44) and the right end wall of the spring cover (37); The crank assembly (5) comprises a crank base (48), the crank base (48) is a tubular sleeve-shaped member, a plurality of connecting ears are arranged on the left end of the crank base (48), one end of each of a plurality of crank bodies (52) is hingedly connected with one of the connecting ears, the crank base (48) is in sealing fit with the outlet side bypass (11), the other end of each of the plurality of crank bodies (52) is in abutting fit with the right end wall of the spring cover (37); The large-diameter end of the bypass reducing flange (7) is connected with the pipe body of the outlet side bypass (11), the bypass reducing flange (7) is in sealing fit with the crank base (48), and the throttling assembly (6) is arranged on the inner hole diameter of the bypass reducing flange (7); The spring seat (49), the second spring (50) and the throttling assembly (6) are sequentially in abutting fit from left to right, the spring seat (49) is bowl-shaped, the mouth rim end (57) of the spring seat (49) is arranged towards left, the mouth rim end (57) is abutted against the right side of the plurality of crank bodies (52), the bowl bottom (54) of the spring seat (49) is provided with a connecting screw hole (55) and a plurality of fourth flow holes (56), the main valve core rod (19) is in threaded fit with the connecting screw hole (55), the second spring (50) is sleeved on the main valve core rod (19), a third positioning hole (61) is formed on the left end face of the first throttling ring (58), and the main valve core rod (19) is in sliding fit with the third positioning hole (61); The back pressure adjusting assembly (4) is arranged at the left end of the diameter of the inlet side bypass (10).

2. A novel air vent check valve according to claim 1, characterized in that: The valve stem assembly (2) further comprises a locking sleeve (17), the inner hole of the throttling sleeve (18) is composed of a throttling hole (20), a balance hole (23) and a first positioning hole (24) connected coaxially in sequence from left to right, a plurality of sealing convex rings (21) are arranged at intervals on the side wall of the throttling hole (20), a plurality of first flow-through holes (22) are arranged circumferentially on the side wall of the balance hole (23), the locking sleeve (17) is fixed at the left end of the throttling sleeve (18), the locking sleeve (17) closes the left end opening of the throttling sleeve (18), the locking sleeve (17) is provided with a second positioning hole (32) and a plurality of second flow-through holes (33), the main valve core stem (19) comprises a second positioning section (25), a sealing section (26), a balance section (28), a first positioning section (29), a connecting section (30) and a third positioning section (31) connected coaxially in sequence from left to right, a plurality of bypass sealing flanges (27) are arranged at intervals on the sealing section (26), the second positioning section (25) is in sliding fit with the second positioning hole (32), an annular cavity is formed between the outer periphery of the balance section (28) and the side wall of the balance hole (23), the left part of the first positioning section (29) is in sliding fit with the first positioning hole (24), and the annular cavity is communicated with the left valve cavity (12) through the plurality of first flow-through holes (22).

3. A novel air vent check valve according to claim 2, characterized in that: The stepped groove is composed of a guide groove (38), a flow-through groove (39) and a balance groove (40) connected coaxially in sequence from left to right, the diameter of the guide groove (38) is smaller than that of the flow-through groove (39) and the balance groove (40), the side wall of the guide groove (38) is in sliding fit with the outer periphery of the throttling sleeve (18), the first positioning section (29) is in sliding sealing fit with the inner periphery of the limiting annular wall (44), a plurality of third flow-through holes (41) are arranged circumferentially on the side wall of the flow-through groove (39), the left valve cavity (12) is communicated with the balance groove (40) through the plurality of third flow-through holes (41) and the flow-through groove (39) in sequence, and the first spring (36) is sleeved on the first positioning section (29).

4. A novel air vent check valve according to claim 1, characterized in that: A concave stop (16) is formed on the right end face of the pipe body of the outlet side bypass (11), the concave stop (16) is coaxial with the outlet side bypass (11), the right end of the crank seat (48) is provided with a positioning flange (53), the bypass reducing flange (7) is pressed in the concave stop (16), and the positioning flange (53) is in stop fit with the concave stop (16).

5. A novel air vent check valve according to claim 1, characterized in that: The throttling assembly (6) comprises a first throttling ring (58) and a plurality of throttling hole plates (59), the first throttling ring (58) and the plurality of throttling hole plates (59) are arranged in sequence from left to right on the inner hole diameter of the bypass reducing flange (7), an axial gap is arranged between the first throttling ring (58) and the adjacent throttling hole plate (59) and between the adjacent two throttling hole plates (59), and a plurality of fifth flow-through holes (60) are formed in the first throttling ring (58).

6. A novel air vent check valve according to claim 5, characterized in that: The edge of the throttling hole plate (59) is provided with a left protruding separation ring structure (62), and the throttling hole plate (59) abuts against the left adjacent throttling hole plate (59) or throttling ring through the separation ring structure (62).

7. A novel air vent check valve according to claim 6, characterized in that: The inner hole of the bypass reducing flange (7) is a stepped hole, a first snap spring (63) is arranged in the inner hole of the bypass reducing flange (7), and the first throttle ring (58) and a plurality of throttle hole plates (59) are axially limited by the snap spring and the inner hole step of the bypass reducing flange (7).

8. A new type of air vent check valve according to any one of claims 1-7, characterized in that: The back pressure adjusting assembly (4) comprises a connecting seat (64), a sealing plate (65), a third spring (66) and an adjusting cover (67), the connecting seat (64) is arranged at the left end of the passage diameter of the inlet side bypass (10), the connecting seat (64) is a tubular member, the connecting seat (64) is provided with a right end wall, the sixth flow-through hole (68) is arranged on the right end wall of the connecting seat (64), the inner periphery of the connecting seat (64) is threadedly connected with the outer periphery of the adjusting cover (67), the adjusting cover (67) is provided with a plurality of seventh flow-through holes, and the sealing plate (65) is pressed on the right end wall of the connecting seat (64) by the third spring (66) to close the fifth flow-through hole (60).

9. A novel air vent check valve according to claim 8, characterized in that: The inlet side bypass (10) is a stepped hole, the second snap spring (69) is arranged in the inlet side bypass (10), and the back pressure adjusting assembly (4) is axially limited by the second snap spring (69) and the inner hole step of the inlet side bypass (10).

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