An ultra-high pressure zero leakage regulating stop vent valve

Abstract

The present invention belongs to the field of hydraulic valves, and specifically relates to an ultra-high pressure zero leakage regulating stop vent valve, comprising: a valve body, a valve cover, a valve stem, a core and a sleeve; the sleeve is installed in a cavity at the upper end of the valve body, an annular cavity is formed between the sleeve and the valve body, a damping channel is provided in the sleeve, and the lower end of the valve stem passes through the valve cover and the sleeve in sequence and is sealably connected to the sleeve; the core is installed in the valve body, and the core is provided with a damping channel, and the fluid medium will undergo three staged energy losses when passing through the core and the sleeve, and is adjusted in stages, and the flow rate of the fluid medium decreases linearly, thereby ensuring the sealing performance under ultra-high pressure conditions while avoiding the occurrence of temperature drops, valve vibrations, severe noises, etc. caused by the rapid decrease in flow rate.

Description

Technical Field

[0001] The invention belongs to the field of hydraulic valves, and in particular relates to an ultra-high pressure zero leakage regulating stop vent valve. Background Art

[0002] Throttling stop vent valves are widely used as closed-circuit devices on pipelines of petroleum, natural gas, coal gas, liquefied petroleum gas, oil refining, airports, chemical industry, oil and gas storage and transportation, etc. The vent valves in the prior art do not use effective adjustable internal parts, and are generally suitable for working conditions of CL1500 and below, and cannot be used for ultra-high pressure working conditions above CL1500. The valve uses ordinary valve sleeve openings to achieve throttling, and the throttling effect is poor. After long-term flushing, the valve sleeve is severely damaged, the service life is short, and the flow regulation cannot be achieved. Furthermore, during the opening process of the valve, due to the single flow channel, the flow rate is often too high, and the high flow rate will cause many hazards, such as: 1) The valve will vibrate violently, causing surging to the pipeline; 2) The temperature inside the valve will drop sharply, causing a cold brittle effect on the valve internals and damage to the valve parts; 3) The valve will produce a large noise, causing harm to the operator.

[0003] Secondly, the main seal of the vent valve in the prior art adopts a triangular ring structure, which is not resistant to erosion. The triangular ring sealing surface is narrow. If there is a little damage, the seal will fail, causing internal leakage, short service life, and not suitable for ultra-high pressure conditions. The valve stem packing adopts a rectangular packing + combined packing form, which is easy to cause low leakage under ultra-high pressure conditions. Summary of the invention

[0004] In order to solve the problems existing in the prior art, the purpose of the present invention is to provide an ultra-high pressure zero leakage regulating cut-off vent valve, which can ensure the sealing performance under ultra-high pressure conditions, ensure zero leakage under ultra-high pressure conditions, and avoid the temperature drop, valve vibration, severe noise and the like caused by the rapid drop in flow rate.

[0005] In order to achieve the above-mentioned object of the invention, the present invention provides the following technical solutions:

[0006] An ultra-high pressure zero leakage regulating stop vent valve, the vent valve comprises: a valve body, a valve cover, a valve stem, a core and a sleeve; the sleeve is installed in the cavity at the upper end of the valve body, a damping channel is arranged in the sleeve, the valve cover is installed at the upper end of the sleeve, a top cover is installed on the outer side of the upper end of the valve body, a hand wheel is installed at the upper end of the top cover, the upper end of the valve stem is connected with the hand wheel in transmission, and the lower end of the valve stem passes through the valve cover and the sleeve in sequence and contacts with the sleeve in a sealing manner;

[0007] Among them, the upstream end of the valve body is sequentially provided with a connected upstream channel and a first intermediate channel, and the downstream end is sequentially provided with a connected second intermediate channel and a downstream channel, the core is installed in the first intermediate channel, a damping channel is arranged in the core, a diversion channel is opened on the lower side of the first intermediate channel, the head end of the diversion channel is connected with the first intermediate channel, the ends of the first intermediate channel and the diversion channel are respectively connected with the confluence cavity, an annular cavity is formed between the sleeve and the valve body, and the annular cavity is connected with the second intermediate channel.

[0008] Preferably, the core includes a first sheet and a second sheet stacked alternately in sequence, and circular grooves are provided on the first sheet and the second sheet, a plurality of first sheet holes are provided along the axial direction of the first sheet, and a plurality of second sheet holes are provided along the axial direction of the second sheet, and the first sheet holes and the second sheet holes are staggered in the circumferential direction to form a damping channel.

[0009] Preferably, the first sheets and the second sheets are alternately stacked and then welded into shape.

[0010] Preferably, the first sheet holes and the second sheet holes are evenly arranged in multiple rows along the circumferential direction, the angle between two adjacent rows of sheet holes is 60°, and each row includes at least two sheet holes.

[0011] Preferably, along the axial direction of the masonry, a first masonry hole is opened on the side close to the masonry core, and the first masonry hole is connected to the confluence chamber. A second masonry hole connected to the first masonry hole is opened on the side away from the masonry core, and the diameter of the second masonry hole is larger than the diameter of the first masonry hole.

[0012] Preferably, along the axial direction of the mashup, a plurality of conical cavities connected with the second mashup hole are evenly arranged in sequence, a plurality of inclined holes are provided at the end of the conical cavity, and the inclined holes are evenly arranged along the circumferential direction of the mashup; at least two circles of vertical holes are also provided along the axial direction of the mashup, the vertical holes are evenly arranged along the circumferential direction of the mashup, and a plurality of the vertical holes intersect with a plurality of the inclined holes to form a damping channel.

[0013] Preferably, the end of the first sleeve hole has an inclined surface which is at an angle to the axial direction of the sleeve, and the end of the inclined surface intersects with a step surface arranged in the radial direction of the sleeve; wherein, the inclined surface is formed with a cemented carbide layer after sealing treatment, and the step surface is respectively formed with a vulcanized rubber structure and a cemented carbide layer after sealing treatment.

[0014] Preferably, the valve stem includes a main body portion, and a conical portion and a step portion are sequentially arranged on the side of the main body portion close to the first sheath hole, wherein the conical portion cooperates with the inclined surface of the first sheath hole to form a first sealing structure of a metal hard seal, and the step portion cooperates with the step surface on the sheath to respectively form a second sealing structure of a planar soft seal and a third sealing structure of a metal hard seal, and the first sealing structure, the second sealing structure and the third sealing structure are sequentially arranged along the radial direction of the sheath.

[0015] Preferably, a sealing assembly is also arranged between the valve stem and the valve cover, and the sealing assembly includes a rectangular packing, a corrugated packing, a first sealing ring, a packing spacer ring, a second sealing ring, a packing gasket, a combined packing, a packing pressure ring and a packing gland which are arranged in sequence along the axial direction of the valve stem; wherein the rectangular packing and the corrugated packing are arranged in an overlapping manner to form a first-level sealing structure; the first sealing ring and the second sealing ring are respectively matched with the outer side and the inner side of the packing spacer ring, and the packing gasket is respectively abutted against the second sealing ring and the packing spacer ring to form a second-level sealing structure; the combined packing, the packing pressure ring and the packing gland are arranged in an overlapping manner to form a third-level sealing structure.

[0016] Compared with the prior art, the ultra-high pressure zero leakage regulating stop vent valve provided by the present invention has the following beneficial technical effects:

[0017] 1. The fluid medium will undergo three stages of energy loss inside the valve body. The flow rate of the fluid medium decreases linearly during staged adjustment, effectively avoiding the temperature drop, valve vibration, severe noise, etc. caused by the rapid decrease in flow rate.

[0018] 2. By adopting a new core structure, the core is formed by stacking and welding multiple layers of fan plates. Each layer of fan plates is provided with fan plate holes arranged in a staggered manner, so that the fluid medium can be regularly divided and converged when passing through the core, so that the flow rate and energy of the fluid medium are reduced.

[0019] 3. By adopting a new type of sleeve structure, the sleeve is cut from forgings, and then several sleeve holes, conical cavities, inclined holes and vertical holes are machined to form a damping channel. When the fluid medium passes through the inclined holes and vertical holes on the sleeve, the fluid medium in the inclined holes will collide with the fluid medium in the vertical holes, reducing the flow rate and energy of the fluid medium.

[0020] 4. The sealing surface of the stop valve adopts a three-sealing structure: the first sealing structure is a metal hard seal formed by the conical surface of the valve stem and the conical inclined surface of the sleeve; the second sealing structure is a flat soft seal formed by the vulcanized rubber structure on the valve stem plane and the step surface of the sleeve. The vulcanized rubber sealing surface is wear-resistant, resistant to flushing, and has a long service life; the third sealing structure is a metal hard seal formed by the valve stem plane and the step surface of the sleeve. The three sealing structures set up in sequence above ensure the sealing performance of the valve under ultra-high pressure and ensure zero leakage under ultra-high pressure conditions.

[0021] 5. The stem packing of the stop valve adopts a composite sealing structure, which consists of a three-level sealing structure consisting of rectangular packing, corrugated packing, O-ring, packing spacer, packing gasket, combined packing, packing pressure ring and packing gland. The first-level sealing structure is rectangular packing + corrugated packing; the second-level sealing structure is O-ring + packing spacer + packing gasket; the third-level sealing structure is combined packing + packing pressure ring + packing gland. The three-level sealing structure realizes ultra-high pressure zero leakage of the valve stem during the opening and closing process. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 This is a structural schematic diagram of the ultra-high pressure zero leakage regulating cut-off vent valve;

[0023] Figure 2 This is a schematic diagram of the structure of the core;

[0024] Figure 3 This is a schematic diagram of the structure of the puzzle piece;

[0025] Figure 4 It is a schematic diagram of the structure of the puzzle;

[0026] Figure 5 This is the axonometric diagram of the maze;

[0027] Figure 6 This is a partial enlarged view of the sealing structure between the valve stem and the sleeve;

[0028] Figure 7 A schematic diagram of the structure of the sealing component.

[0029] The meanings of the symbols in the figure are as follows:

[0030] 1. Valve body; 2. Valve cover; 3. Top cover; 4. Hand wheel; 5. Valve stem; 6. Sealing assembly; 7. Core; 8. Sleeve;

[0031] 11. upstream channel; 12. downstream channel; 13. first intermediate channel; 14. second intermediate channel; 15. diversion channel; 16. confluence cavity; 17. annular cavity;

[0032] 51. main body; 52. conical portion; 53. step portion;

[0033] 61. Rectangular packing; 62. Corrugated packing; 63. Packing spacer ring; 64. First sealing ring; 65. Second sealing ring; 66. Packing washer; 67. Combined packing; 68. Packing pressure ring; 69. Packing gland;

[0034] 71, first puzzle piece; 72, second puzzle piece; 73, groove; 74, first puzzle piece hole; 75, second puzzle piece hole;

[0035] 81. First maze hole; 82. Second maze hole; 83. Conical cavity; 84. Oblique hole; 85. Vertical hole; 86. Inclined surface; 87. First sealing structure; 88. Second sealing structure; 89. Third sealing structure. DETAILED DESCRIPTION

[0036] To make the purpose, technical solution and advantages of the embodiments of the present invention clearer, the technical solution in the embodiments of the present invention will be described clearly and completely in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of them.

[0037] Therefore, the following detailed description of the embodiments of the present invention is not intended to limit the scope of the invention claimed for protection, but merely represents some embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0038] It should be noted that, in the absence of conflict, the embodiments of the present invention and the features and technical solutions in the embodiments may be combined with each other.

[0039] It should be noted that similar reference numerals and letters denote similar items in the following drawings, and therefore, once an item is defined in one drawing, further definition and explanation thereof is not required in subsequent drawings.

[0040] In the description of the present invention, it should be noted that the orientation or positional relationship indicated by the terms "upper", "lower", etc. is based on the orientation or positional relationship shown in the drawings, or the orientation or positional relationship in which the invention product is usually placed when in use, or the orientation or positional relationship commonly understood by those skilled in the art. Such terms are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as limiting the present invention. In addition, the terms "first", "second", etc. are only used to distinguish the description, and cannot be understood as indicating or implying relative importance.

[0041] See attached Figure 1 -Attached Figure 7As shown, the present invention provides an ultra-high pressure zero leakage regulating stop vent valve, which comprises: a valve body 1, a valve cover 2, a top cover 3, a hand wheel 4, a valve stem 5, a sealing assembly 6, a core 7, and a sleeve 8. A sleeve 8 is installed in the cavity at the upper end of the valve body 1, a damping channel is arranged in the sleeve 8, a valve cover 2 is installed at the upper end of the sleeve 8, a top cover 3 is installed on the outer side of the upper end of the valve body 1, a hand wheel 4 is installed at the upper end of the top cover 3, the upper end of the valve stem 5 is drivingly connected with the hand wheel 4, and the lower end of the valve stem 5 passes through the valve cover 2 and the sleeve 8 in sequence, and then contacts with the sleeve 8 in a sealing manner;

[0042] Among them, the upstream end of the valve body 1 is sequentially provided with an upstream channel 11 and a first intermediate channel 13 that are connected, and the downstream end is sequentially provided with a second intermediate channel 14 and a downstream channel 12 that are connected. A core 7 is installed in the first intermediate channel 13, and a damping channel is arranged in the core 7. A diverter channel 15 is opened on the lower side of the first intermediate channel 13. The head end of the diverter channel 15 is connected to the first intermediate channel 13, and the ends of the first intermediate channel 13 and the diverter channel 15 are respectively connected to a confluence chamber 16. The confluence chamber 16 and the masonry sleeve 8 can be sealed or connected through the valve stem 5. An annular cavity 17 is formed between the masonry sleeve 8 and the valve body 1, and the annular cavity 17 is connected to the second intermediate channel 14.

[0043] According to the vent valve in this embodiment, after the fluid medium flows through the upstream channel 11, it is diverted at the first intermediate channel 13. A part of the fluid medium enters the confluence chamber 16 through the first intermediate channel 13. When this part of the fluid medium passes through the damping channel in the core 7, the fluid medium will be regularly diverted and converged, thereby reducing the flow rate and energy of the fluid medium. Another part of the fluid medium enters the confluence chamber 16 through the diversion channel 15. The two parts of the medium converge at the confluence chamber 16. During the confluence process, the fluid medium will collide, the energy of the fluid medium will be further lost, and the flow rate will further decrease. Subsequently, the fluid medium after confluence flows upward and enters the downstream channel 12 through the sheath 8, the annular cavity 17, and the second intermediate channel 14. When the fluid medium passes through the damping channel in the sheath 8, the fluid medium will also collide, and its energy and flow rate will be further reduced. Therefore, the fluid medium will undergo three stages of energy loss inside the valve body and be adjusted in stages. The flow rate of the fluid medium decreases linearly, effectively avoiding the temperature drop, valve vibration, severe noise, etc. caused by the rapid decrease in flow rate.

[0044] Preferably, the core 7 includes first and second pieces 71 and 72 which are alternately stacked and welded. The first and second pieces 71 and 72 are alternately stacked and welded. A circular groove 73 is provided on each of the first and second pieces 71 and 72. A plurality of first piece holes 74 are provided along the axial direction of the first piece 71 and a plurality of second piece holes 75 are provided along the axial direction of the second piece 72. The first and second piece holes 74 and 75 are staggered in the circumferential direction to form a damping channel, so that the fluid medium flowing through the core 7 is regularly divided and merged. Figure 2 As shown by the middle arrow, the fluid medium will flow through the first and second flap holes on the fan core, so that the fluid medium can be regularly divided and merged, reducing the flow rate and energy of the fluid medium.

[0045] The first sheet holes 74 and the second sheet holes 75 are evenly arranged in multiple rows along the circumferential direction, and the angle θ between two adjacent rows of sheet holes is 60°. Each row includes at least two sheet holes, preferably three sheet holes. The closer the second sheet hole 75 is to the center of the circle, the larger its diameter is, so that the fluid medium can be regularly diverted and converged when passing through the core.

[0046] In the above preferred embodiment, by adopting a new core structure, the core is formed by stacking and welding multiple layers of fan sheets. Each layer of fan sheets is provided with fan sheet holes arranged in a staggered manner, and the fluid medium can be regularly divided and merged when passing through the core, so that the flow rate and energy of the fluid medium are reduced.

[0047] Preferably, along the axial direction of the sheath 8, a first sheath hole 81 is provided on the side close to the core 7, the first sheath hole 81 is connected to the confluence chamber 16, and a second sheath hole 82 is provided on the side away from the core 7, which is connected to the first sheath hole 81, and the diameter of the second sheath hole 82 is greater than the diameter of the first sheath hole 81. At the same time, along the axial direction of the sheath 8, a plurality of conical cavities 83 connected to the second sheath hole 82 are uniformly arranged in sequence, the conical cavities 83 are roughly funnel-shaped, and a plurality of inclined holes 84 are provided at the end of the conical cavity 83, and the inclined holes 84 are uniformly arranged along the circumferential direction of the sheath 8; at least two circles of vertical holes 85 are also provided along the axial direction of the sheath 8, the vertical holes 85 are uniformly arranged along the circumferential direction of the sheath 8, a plurality of vertical holes 85 intersect with a plurality of inclined holes 84, and the ends of the conical cavities 83 partially intersect with the vertical holes 85 of the inner circle to form a damping channel. The vertical hole 85 and the inclined hole 84 have the same diameter, and the angle α between the inclined hole 84 and the horizontal plane is 20° to 30°.

[0048] In the above preferred embodiment, by adopting a new type of sleeve structure, the sleeve is blanked by forging, and then a plurality of sleeve holes, conical cavities, inclined holes and vertical holes are machined to form a damping channel. When the fluid medium passes through the inclined holes and vertical holes on the sleeve, the fluid medium in the inclined holes will collide with the fluid medium in the vertical holes, reducing the flow rate and energy of the fluid medium.

[0049] Preferably, the end of the first sleeve hole 81 has an inclined surface 86 which is at a certain angle to the axial direction of the sleeve 8, and the end of the inclined surface 86 intersects with a step surface arranged in the radial direction of the sleeve 8. Wherein, the inclined surface 86 is formed with a hard alloy layer after the sealing treatment, and the step surface is respectively formed with a vulcanized rubber structure and a hard alloy layer after the sealing treatment. The valve stem 5 includes a main body 51, and a conical portion 52 and a step portion 53 are sequentially arranged on one side of the main body 51 close to the first sleeve hole 81, wherein the conical portion 52 cooperates with the inclined surface 86 of the first sleeve hole 81 to form a first sealing structure 87 of metal hard sealing, and the step portion 53 cooperates with the step surface on the sleeve 8 to respectively form a second sealing structure 88 of planar soft sealing and a third sealing structure 89 of metal hard sealing, and the first sealing structure 87, the second sealing structure 88 and the third sealing structure 89 are sequentially arranged along the radial direction of the sleeve 8.

[0050] In the above preferred embodiment, the sealing surface of the stop valve adopts a three-sealing structure: the first sealing structure is a metal hard seal formed by the conical surface of the valve stem and the conical inclined surface of the sleeve; the second sealing structure is a plane soft seal formed by the vulcanized rubber structure on the valve stem plane and the step surface of the sleeve, and the vulcanized rubber sealing surface is wear-resistant, resistant to flushing, and has a long service life; the third sealing structure is a metal hard seal formed by the valve stem plane and the step surface of the sleeve. The three sealing structures arranged in sequence above ensure the sealing performance of the valve under ultra-high pressure and ensure zero leakage under ultra-high pressure conditions.

[0051] Preferably, a sealing assembly 6 is further arranged between the valve stem 5 and the valve cover 2, and the sealing assembly 6 includes a rectangular packing 61, a corrugated packing 62, a first sealing ring 64, a packing spacer ring 63, a second sealing ring 65, a packing gasket 66, a combined packing 67, a packing pressure ring 68 and a packing gland 69 which are arranged in sequence along the axial direction of the valve stem 5; wherein the rectangular packing 61 and the corrugated packing 62 are arranged in an overlapping manner to form a first-level sealing structure; the first sealing ring 64 and the second sealing ring 65 are respectively matched with the outer side and the inner side of the packing spacer ring 63, and the packing gasket 66 is respectively abutted against the second sealing ring 65 and the packing spacer ring 63 to form a second-level sealing structure; the combined packing 67, the packing pressure ring 68 and the packing gland 69 are arranged in an overlapping manner to form a third-level sealing structure.

[0052] In the above preferred embodiment, the stem packing of the stop valve adopts a composite sealing structure, which is composed of a rectangular packing, a corrugated packing, an O-ring, a packing spacer, a packing gasket, a combined packing, a packing pressure ring and a packing gland to form a three-level sealing structure. The first-level sealing structure is a rectangular packing + a corrugated packing; the second-level sealing structure is an O-ring + a packing spacer + a packing gasket; the third-level sealing structure is a combined packing + a packing pressure ring + a packing gland, and the three-level sealing structure realizes ultra-high pressure zero leakage of the valve stem during the opening and closing process.

[0053] The above embodiments are only used to illustrate the present invention and are not intended to limit the technical solutions described in the present invention. Although the present invention has been described in detail with reference to the above embodiments, the present invention is not limited to the above specific implementation methods. Therefore, any modification or equivalent replacement of the present invention; and all technical solutions and improvements thereof that do not depart from the spirit and scope of the invention are included in the scope of the claims of the present invention.

Claims

1. An ultra-high pressure zero leakage regulating stop vent valve, characterized in that: The vent valve comprises: a valve body, a valve cover, a valve stem, a core and a sleeve; the sleeve is installed in the cavity at the upper end of the valve body, a damping channel is provided in the sleeve, the valve cover is installed at the upper end of the sleeve, a top cover is installed on the outer side of the upper end of the valve body, a hand wheel is installed at the upper end of the top cover, the upper end of the valve stem is connected to the hand wheel in a transmission manner, and the lower end of the valve stem passes through the valve cover and the sleeve in sequence and contacts with the sleeve in a sealing manner; The upstream end of the valve body is provided with a connected upstream channel and a first intermediate channel in sequence, and the downstream end is provided with a connected second intermediate channel and a downstream channel in sequence, the fan core is installed in the first intermediate channel, a damping channel is provided in the fan core, a shunt channel is opened on the lower side of the first intermediate channel, the head end of the shunt channel is connected with the first intermediate channel, the ends of the first intermediate channel and the shunt channel are respectively connected with the confluence cavity, an annular cavity is formed between the fan sleeve and the valve body, and the annular cavity is connected with the second intermediate channel; The core comprises a first fan plate and a second fan plate which are alternately stacked in sequence, wherein the first fan plate and the second fan plate are both provided with a circular groove, a plurality of first fan plate holes are provided along the axial direction of the first fan plate, and a plurality of second fan plate holes are provided along the axial direction of the second fan plate, and the first fan plate holes and the second fan plate holes are staggered in the circumferential direction to form a damping channel; Along the axial direction of the sheath, a first sheath hole is opened on the side close to the sheath core, the first sheath hole is communicated with the confluence chamber, and a second sheath hole is opened on the side away from the sheath core and communicated with the first sheath hole, and the diameter of the second sheath hole is greater than the diameter of the first sheath hole; The end of the first sleeve hole has an inclined surface which is at an angle to the axial direction of the sleeve, and the end of the inclined surface intersects with a step surface arranged in the radial direction of the sleeve; wherein the inclined surface is formed with a hard alloy layer after sealing treatment, and the step surface is respectively formed with a vulcanized rubber structure and a hard alloy layer after sealing treatment; The valve stem includes a main body portion, and a conical portion and a step portion are sequentially arranged on one side of the main body portion close to the first sheath hole, wherein the conical portion cooperates with the inclined surface of the first sheath hole to form a first sealing structure of a metal hard seal, and the step portion cooperates with the step surface on the sheath to respectively form a second sealing structure of a planar soft seal and a third sealing structure of a metal hard seal, and the first sealing structure, the second sealing structure and the third sealing structure are sequentially arranged along the radial direction of the sheath.

2. The vent valve according to claim 1, characterized in that: The first sheets and the second sheets are alternately stacked and then welded into shape.

3. The vent valve according to claim 2, characterized in that: The first sheet holes and the second sheet holes are evenly arranged in multiple rows along the circumferential direction, the angle between two adjacent rows of sheet holes is 60°, and each row includes at least two sheet holes.

4. The vent valve according to claim 3, characterized in that: Along the axial direction of the mashup, a number of conical cavities connected with the second mashup hole are evenly arranged in sequence, and a number of inclined holes are opened at the end of the conical cavity, and the inclined holes are evenly arranged along the circumferential direction of the mashup; at least two circles of vertical holes are also opened along the axial direction of the mashup, and the vertical holes are evenly arranged along the circumferential direction of the mashup, and a number of the vertical holes intersect with a number of the inclined holes to form a damping channel.

5. The vent valve according to claim 4, characterized in that: A sealing assembly is also arranged between the valve stem and the valve cover, and the sealing assembly includes a rectangular packing, a corrugated packing, a first sealing ring, a packing spacer ring, a second sealing ring, a packing gasket, a combined packing, a packing pressure ring and a packing gland which are arranged in sequence along the axial direction of the valve stem; wherein the rectangular packing and the corrugated packing are overlapped to form a first-level sealing structure; the first sealing ring and the second sealing ring are respectively matched with the outer side and the inner side of the packing spacer ring, and the packing gasket is respectively abutted against the second sealing ring and the packing spacer ring to form a second-level sealing structure; the combined packing, the packing pressure ring and the packing gland are overlapped in sequence to form a third-level sealing structure.

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