CN218625653U - Main valve structure of pilot axial flow type safety valve - Google Patents

Abstract

The utility model discloses a main valve structure of guide's axial-flow type relief valve relates to natural gas gathering pipeline and uses valve technical field. The hollow sliding sleeve and the diaphragm chamber are arranged in the main valve of the utility model, the hollow sliding sleeve penetrates through the diaphragm chamber, and the outer wall of the sliding sleeve is in sliding seal with the side walls at the upper end and the lower end of the diaphragm chamber; one end of the sliding sleeve is in contact fit with a sealing surface at a corresponding gas outlet in the main valve to form a sealing pair; a diaphragm is fixedly arranged in the diaphragm chamber, and the diaphragm chamber is divided into a diaphragm cavity I and a diaphragm cavity II by the diaphragm; the sliding sleeve penetrates through the middle part of the diaphragm and is fixed with the diaphragm through the tray assembly; under the action of the pressure difference between the diaphragm cavity I and the diaphragm cavity II, the diaphragm drives the sliding sleeve to move. The utility model discloses can effectively solve because of the fluid direction changes the vibrations that the grow arouses to solve the problem that the part that arouses because of vibrations is not hard up, set for pressure variation and accuse pressure precision reduces.

Description

Main valve structure of pilot axial flow type safety valve

Technical Field

The utility model relates to a natural gas gathering pipeline is with valve technical field, more specifically the main valve structure that relates to a guide's axial-flow type relief valve that says so.

Background

With the rapid development of economy in China, various high-pressure gases are increasingly widely applied in the fields of industry and civilian use, such as the distribution of long-distance pipelines of natural gas, regional gas supply and the like. The overpressure caused by various reasons causes the failure of the pipeline or container carrying high-pressure gas, and the sudden release of the gas in the pipeline due to high compression generates shock waves, which cause destructive damage to nearby residents or buildings. In view of this, the domestic and foreign control methods for such events mostly adopt a mode of limiting overpressure release, namely, safety pressure release.

The traditional safety valve is of a common spring type, namely, the traditional safety valve directly starts to jump and drain after exceeding the pre-applied spring force, or opens a main valve to drain through the opening of a pilot valve.

The national intellectual property office discloses a utility model patent with publication number CN208764401U and name "a low-pressure pilot-operated safety valve" in 2019, 19.4.19.9, the utility model patent comprises a pilot valve and a main valve, wherein the pilot valve comprises a pilot valve seat, a middle valve box, a pilot valve membrane, an upper valve cover, a pilot valve clack and a connecting shaft; the main valve includes main valve body, main valve disk seat, case pole, main valve case, main valve barrel, main valve gap, main valve diaphragm and reset spring, and the pilot valve utilizes area pressure differential relation, and the pilot valve is opened rapidly, and this structure is opened suddenly and is used apparently, and the superpressure is opened promptly, and the main valve adopts full balanced structure, and this utility model's pilot valve is opened rapidly, and the sudden opening is obvious, and the superpressure is opened promptly, and the reaction is fast, and the flow resistance coefficient characteristic is used in the pilot valve export, and the design export chooses for use 10% -50% for use for the valve to open the response rapidly, and it is fast to return the seat.

The gas in the main valve of the common safety valve generates a recoil action due to the forced guiding of the valve body, so that the safety valve bears high vibration, the safety valve is difficult to reset, the set pressure is changed, and the pressure control precision is reduced.

SUMMERY OF THE UTILITY MODEL

In order to overcome the defect and not enough that exist among the above-mentioned prior art, the utility model provides a main valve structure of guide's axial-flow type relief valve, the utility model discloses an invention aim at produce higher vibration when solving main valve pressure release among the prior art, lead to relief valve difficulty that resets, set pressure to change and the problem of accuse pressure precision decline. The utility model is provided with a hollow sliding sleeve and a diaphragm chamber in the main valve, the hollow sliding sleeve penetrates through the diaphragm chamber, and the outer wall of the sliding sleeve is in sliding seal with the side walls at the upper and lower ends of the diaphragm chamber; one end of the sliding sleeve is in contact fit with a sealing surface at a corresponding gas outlet in the main valve to form a sealing pair; a diaphragm is fixedly arranged in the diaphragm chamber, and the diaphragm chamber is divided into a diaphragm cavity I and a diaphragm cavity II by the diaphragm; the sliding sleeve penetrates through the middle part of the diaphragm and is fixed with the diaphragm through the tray assembly; under the action of the pressure difference between the diaphragm cavity I and the diaphragm cavity II, the diaphragm drives the sliding sleeve to move. The utility model discloses can effectively solve the vibrations that arouse because of the fluid direction changes the grow to solve the problem that the part is not hard up, set for pressure variation and accuse pressure accuracy reduces that arouses because of vibrations.

In order to solve the problems existing in the prior art, the utility model discloses a realize through following technical scheme:

the main valve structure of the pilot axial flow type safety valve is characterized in that a hollow sliding sleeve and a diaphragm chamber are arranged in the main valve, the hollow sliding sleeve penetrates through the diaphragm chamber, and the outer wall of the sliding sleeve is in sliding seal with the side walls of the upper end and the lower end of the diaphragm chamber; one end of the sliding sleeve is in contact fit with a sealing surface at a corresponding gas outlet in the main valve to form a sealing pair; a diaphragm is fixedly arranged in the diaphragm chamber, and the diaphragm divides the diaphragm chamber into a diaphragm cavity I and a diaphragm cavity II; the sliding sleeve penetrates through the middle part of the diaphragm and is fixed with the diaphragm through the tray assembly; under the action of the pressure difference between the diaphragm cavity I and the diaphragm cavity II, the diaphragm drives the sliding sleeve to move.

The main valve includes that main mode lid I, main mode lid II and gaseous outlet joint, form behind II flange joint of main mode lid I and main mode lid the diaphragm room, the gaseous import setting of main valve is on main mode lid I, and gaseous outlet joint installs on main mode lid II.

And the sliding sleeve is respectively in sliding seal with the main die cover I and the main die cover II.

And a closing spring is arranged in the diaphragm cavity I.

The utility model discloses in, the principle of closing of main valve does: the sliding sleeve seals the sliding sleeve and the main valve mold cover II through a sealing ring, and when the sliding sleeve is contacted with a sealing surface on a main valve gas outlet joint, the main valve is in a closed state; the sliding sleeve is sealed with a main valve mold cover I through a sealing ring, a diaphragm is arranged in a diaphragm chamber and connected with the sliding sleeve, the diaphragm separates the diaphragm chamber into a diaphragm chamber I and a diaphragm chamber II, and the reciprocating movement of the sliding sleeve is pushed by controlling the pressure difference between the diaphragm chamber I and the diaphragm chamber II to realize the closing and opening of a sealing surface on a gas outlet joint of the sliding sleeve and the main valve so as to control the opening and closing of the main valve.

Compared with the prior art, the utility model discloses profitable technological effect who brings shows in:

1. the utility model discloses in adopt hollow sliding sleeve and the sealed face direct contact realization main valve of the gaseous exit end of main valve to open and close, front end pressure is around the sliding sleeve along the radial even action of sliding sleeve this moment, and the sliding sleeve does not receive the axial pressure that the front end was applyed, and the axial pressure of front end pressure is direct action on sealed face, and then the rear end pressure also is around radial action sliding sleeve, and the axial pressure of rear end also is direct action on sealed face. At the moment, the sliding sleeve is not stressed axially at the front end and the rear end, so that the front end pressure and the rear end pressure are not influenced when the sliding sleeve moves axially. The utility model discloses a main valve structure is only acted on by the frictional force of sealing washer and contact surface to the atress of opening and closing of main valve, the process essence of opening and closing is sliding sleeve's axial motion process, the power of opening and close comes from the pressure differential of diaphragm chamber I and diaphragm chamber II, even there is the backpressure to exist, the backpressure also is on the radial action sliding sleeve lateral wall, the sliding sleeve axial does not receive the effect of backpressure when the main valve is closed, when the main valve is opened, sliding sleeve axial atress face is sliding sleeve tip area, and there is not the area difference in the front and back end, the front and back end pressure difference that receives when consequently opening and closing can neglect. Therefore, the safety valve of the utility model can ignore the influence of the back pressure on the movement of the sliding sleeve, and can bear the ultrahigh back pressure.

2. The prior art is limited by a main valve structure of a traditional safety valve, so that the outlet discharge space has to change the fluid direction, for example, the fluid is discharged from the side at 90 degrees, and the flow channel forcibly changes the fluid flow channel direction in the discharging process, so that the safety valve generates strong vibration, and the pressure setting or other parts of the safety valve are loosened in the vibration process, thereby causing the problem of reduced pressure control precision. The utility model discloses a main valve is axial-flow type structure, and adopts hollow sliding sleeve, and sliding sleeve is coaxial with gas feed and gas outlet, and the fluid direction changes for a short time in the emission process, can effectively solve the vibrations that change the grow and arouse because of the fluid direction to solve the part that arouses because of vibrations not hard up, set for the problem that pressure variation and accuse pressure accuracy reduce.

Drawings

Fig. 1 is a schematic cross-sectional structural view of a main valve structure of a pilot axial flow safety valve according to the present application;

FIG. 2 is a schematic view of the sliding sleeve under load when the main valve structure of the present application is closed;

FIG. 3 is a schematic view of the main valve structure of the present application with the sliding sleeve forced open;

FIG. 4 is a cross-sectional structural view of the main valve structure of the present application when closed with a safety valve formed after the main valve structure is connected to a pilot valve;

FIG. 5 is a cross-sectional structure diagram of the main valve structure of the present application when the safety valve formed by connecting the pilot valve is opened;

reference numerals: 1. the pilot valve, 2, a main valve, 3, a sliding sleeve, 4, a diaphragm chamber, 5, a gas outlet, 6, a sealing surface, 7, a diaphragm, 8, a diaphragm cavity I, 9, a diaphragm cavity II, 10, a tray assembly, 11, an adjusting spring assembly, 12, a pilot valve core, 13, a pilot valve seat, 14, an air inlet cavity, 15, a discharge cavity, 16, a balance cavity, 17, a damping hole II, 18, a fixed nozzle, 19, a vulcanized valve seat, 20, a signal pipe, 21, a damping hole I, 22, a pressure relief opening, 23, a communication hole, 24, a piston I, 25, a piston II, 26, a piston III, 27, a piston shaft, 28, a main valve mold cover I, 29, a main valve mold cover II, 30, a gas outlet joint, 31 and a closing spring.

Detailed Description

The technical scheme of the invention is further elaborated in the following in combination with the attached drawings of the specification. Here, the description of the embodiments is provided to help understanding of the present invention, but the present invention is not limited thereto. In addition, the technical features involved in the respective embodiments of the present invention described below may be combined with each other as long as they do not conflict with each other.

Referring to the attached figure 1 of the specification, a hollow sliding sleeve 3 and a diaphragm chamber 4 are arranged in a main valve 2, the hollow sliding sleeve 3 penetrates through the diaphragm chamber 4, and the outer wall of the sliding sleeve 3 is in sliding seal with the side walls of the upper end and the lower end of the diaphragm chamber 4; one end of the sliding sleeve 3 is contacted and matched with a sealing surface 6 at the position corresponding to the gas outlet 5 in the main valve 2 to form a sealing pair; a diaphragm 7 is fixedly arranged in the diaphragm chamber 4, and the diaphragm 7 divides the diaphragm chamber 4 into a diaphragm cavity I8 and a diaphragm cavity II 9; the sliding sleeve 3 penetrates through the middle part of the diaphragm 7 and is fixed with the diaphragm 7 through the tray component 10; under the action of the pressure difference between the diaphragm cavity I8 and the diaphragm cavity II 9, the diaphragm 7 drives the sliding sleeve 3 to move.

The main valve 2 comprises a main valve mold cover I28, a main valve mold cover II 29 and a gas outlet connector 30, the main valve mold cover I28 and the main valve mold cover II 29 are connected through flanges to form the diaphragm chamber 4, a gas inlet of the main valve 2 is formed in the main valve mold cover I28, and the gas outlet connector 30 is installed on the main valve mold cover II 29. The sliding sleeve 3 is respectively in sliding seal with a main valve mould cover I28 and a main valve mould cover II 29. And a closing spring 31 is arranged in the diaphragm cavity I8.

As shown in fig. 1, the sliding sleeve 3 seals the sliding sleeve 3 and the main valve cover ii 29 with a seal ring, and when the sliding sleeve 3 contacts the seal surface 6 on the gas outlet joint 30 of the main valve 2, that is, the main valve 2 is in a closed state; sliding sleeve 3 is airtight through sealing washer and master valve mould lid I28, sets up diaphragm 7 in the diaphragm chamber 4, and diaphragm 7 links to each other with sliding sleeve 3, and diaphragm 7 separates diaphragm chamber 4 for diaphragm chamber I8 and diaphragm chamber II 9, through the pressure differential between I8 of control diaphragm chamber and the diaphragm chamber II 9, promotes sliding sleeve 3's reciprocating motion, realizes sliding sleeve 3 and the closure and the opening of the sealed face 6 on the 2 gas outlet joint 30 of master valve to control opening and close of master valve 2.

As shown in fig. 2 and 3, the sliding sleeve 3 is closed when it contacts the sealing surface 6 of the gas outlet connection 30 of the main valve 2; at this time, the stress is shown in fig. 2 and 3, the front end pressure P1 uniformly acts on the periphery of the shaft, the axial pressure P1 acts on the fixed sealing surface 6, the pressure of the downstream part is P2, and at this time, the P2 uniformly acts on the outer circumferential direction of the sliding main shaft and the back of the fixed sealing surface 6 in the axial direction; the sealing surface 6 is in a complete balance state under the axial stress of P1= P2; the stressed state of the sliding sleeve 3 is that the area of the linear contact surface of the sliding sleeve 3 and the sealing surface 6 approaches to 0, so that the stress of the sliding main shaft in the axial direction tends to zero when the sliding main shaft is closed, and therefore, the stress of the structure on the opening and closing states of the valve is only acted by the friction force of the sealing ring and the contact surface, so the opening and closing force can be ignored. The opening and closing process of the main valve 2 is substantially the axial movement process of the sliding sleeve 3, and the opening and closing power comes from the pressure difference between the diaphragm cavity I8 and the diaphragm cavity II 9; if the back pressure P2 exists, the pressure of the P2 is uniformly applied to the outer wall of the sleeve, the sleeve is not axially affected by the back pressure when the sleeve is closed, and the stressed area of the sleeve is about zero when the sleeve is opened, so that the influence on the movement of the sleeve is almost ignored no matter how large the back pressure exists, and the ultrahigh back pressure can be resisted.

As an embodiment of the present invention, with the main valve structure replacement publication number of this application being CN208764401U, the main valve in the utility model patent named "a low pressure pilot operated safety valve", then be linked together the pilot valve in diaphragm chamber i 8 and this patent, pass through signal pipe with diaphragm chamber ii 9 and connect in the main valve front end pipeline. The control principle is similar to that in the above patent.

As another embodiment of the present invention, in this embodiment, a pilot valve structure is provided, in which a pilot valve and a main valve mechanism of the present application are connected together to form a pilot axial flow safety valve, as shown in fig. 4 and 5, a piston assembly is slidably disposed in the pilot valve 1, one end of the piston assembly is connected to an adjusting spring assembly 11, and the other end of the piston assembly is connected to a pilot valve core 12, in an initial state, an acting force of the adjusting spring assembly 11 acts on the pilot valve core 12 through the piston assembly, and the pilot valve core 12 is pressed on a pilot valve seat 13 in the pilot valve 1 to be in a sealed state; the piston assembly divides an inner cavity of the pilot valve 1 into an air inlet cavity 14, a drain cavity 15 and a balance cavity 16, and the air inlet cavity 14 is communicated with the drain cavity 15 through a damping hole II 17; a fixed nozzle 18 is arranged in the balance cavity 16, and a vulcanizing valve seat 19 for plugging the fixed nozzle 18 is arranged on the piston assembly; the air at the inlet end of the main valve 2 enters the air inlet cavity 14 through the signal pipe 20 via the damping hole I21 at the air inlet of the pilot valve 1 and the pilot valve seat 13; meanwhile, the water enters a balance cavity 16 through a fixed nozzle 18, and the balance cavity 16 is communicated with a diaphragm cavity II 9 through a signal tube 20; the discharge cavity 15 is communicated with a pressure relief port 22; a communicating hole 23 is formed in the valve body of the pilot valve 1, and the communicating hole 23 is communicated with the diaphragm cavity I8 through a signal pipe 20; when a vulcanized valve seat 19 on the piston assembly is sealed with the fixed nozzle 18, the diaphragm cavity I8 is communicated with the discharge cavity 15 through the communicating hole 23; when the pilot valve core 12 at the end of the piston assembly is sealed with the pilot valve seat 13, the diaphragm chamber I8 is communicated with the balance chamber 16 through the communication hole 23.

The piston assembly comprises a piston I24, a piston II 25 and a piston III 26, and the piston I24, the piston II 25 and the piston III 26 are in sliding seal with the inner cavity wall of the pilot valve 1; the areas of the piston I24, the piston II 25 and the piston III 26 are the same; the end part of the piston I24 and the pilot valve 1 forms the air inlet cavity 14, the discharge cavity 15 is formed between the piston I24 and the piston II 25, and air in the air inlet cavity 14 enters the discharge cavity 15 from the damping hole II 17 on the piston I24; the balance cavity 16 is formed between the piston II 25 and the piston III 26, and the vulcanized valve seat 19 is arranged on the piston II 25.

The communication hole 23 is arranged on the side wall of the inner cavity of the pilot valve 1 in the operation stroke of the piston II 25. The piston assembly further comprises a piston shaft 27, and the piston I24, the piston II 25 and the piston III 26 are fixedly arranged on the piston shaft 27 in parallel; one end of the piston shaft 27 is connected with the pilot valve core 12, and the other end is connected with the adjusting spring assembly 11; the diameter of one end of the piston shaft 27 connected with the pilot valve core 12 is smaller than the diameter of the section of the piston shaft 27 between the piston I24, the piston II 25 and the piston III 26.

As shown in fig. 4, the main valve 2 is in a closed state when operating normally, and the pilot valve 1 is also in a closed state at this time, the pressure difference between the diaphragm chamber i 8 and the diaphragm chamber ii 9 of the main valve 2 is 0, and both the diaphragm chamber i 8 and the diaphragm chamber ii 9 are communicated with the balance chamber 16 of the pilot valve 1. The method specifically comprises the following steps: in an initial state, gas enters the gas inlet of the pilot valve 1 from the gas inlet end of the main valve 2 through the stop valve and the signal process pipe, enters the pilot valve seat 13 through the damping hole I21 at the gas inlet of the pilot valve 1, and contacts with the pilot valve core 12 (at the moment, the pilot valve core 12 and the pilot valve seat 13 are in a closed state); the piston assembly of the pilot valve 1 isolates the inner cavity of the pilot valve 1 into an air inlet cavity 14, a drain cavity 15 and a balance cavity 16, and the drain cavity 15 is provided with a drain outlet for draining air or connecting an air drain pipeline; the communicating hole 23 which is communicated with the diaphragm chamber I8 of the main valve 2 is positioned in the balance chamber 16; the modulating spring assembly 11 transmits force through the piston assembly to the pilot spool 12 causing the pilot spool 12 to close with the pilot valve seat. At the same time, the gas enters the fixed nozzle 18 from the gas inlet end of the main valve 2, the piston assembly is pressed to the lower limit under the set acting force of the adjusting spring assembly 11, at this time, the nozzle on the fixed nozzle 18 is separated from the vulcanized valve seat 19 on the piston assembly, the gas enters the balance cavity 16 through the fixed nozzle 18, and is communicated with the diaphragm cavity II 9 of the main valve 2 through the signal pipe joint on the balance cavity 16. At this time, the diaphragm cavity I8 and the diaphragm cavity II 9 are both communicated with the balance cavity 16 of the pilot valve 1, and the pressure difference between the diaphragm cavity I8 and the diaphragm cavity II 9 of the main valve 2 is 0.

As shown in fig. 5, after the pipeline pressure is over-pressurized, the pressure gas at the gas inlet end of the main valve 2 contacts the pilot valve core 12 through the damping hole i 21 of the gas inlet of the pilot valve 1 and the valve seat, at this time, the thrust generated by the high-pressure gas to the pilot valve core 12 is greater than the set spring pressure of the adjusting spring assembly 11, the pilot valve core 12 is slightly pushed open, the high-pressure gas enters the gas inlet cavity 14, the area of the piston i 24 is greater than the area of the pilot valve core 12, the high-pressure gas acts on the piston i 24, the acting area of the high-pressure gas is greatly increased, the generated thrust is increased accordingly, the stroke of the piston assembly reaches the maximum position, that is, the pilot valve 1 is in the full open state.

When the pilot valve 1 is in a full-open state, the vulcanizing valve seat 19 on the piston II 25 blocks the fixed nozzle 18, and the piston II 25 moves to the other side of the communication hole 23, so that the communication hole 23 is communicated with the drainage cavity 15; the balancing chamber 16 is now in a closed state; the diaphragm cavity I8 of the main valve 2 is communicated with the discharge cavity 15, and the gas pressure in the diaphragm cavity I8 is discharged; when the diaphragm cavity I8 of the main valve 2 is decompressed, the pressure in the diaphragm cavity II 9 of the main valve 2 is inconvenient to form a large pressure difference, the diaphragm 7 of the main valve 2 and the tray assembly 10 are pushed to move the sliding sleeve 3 to the gas inlet end of the main valve 2, so that the sliding sleeve 3 is separated from the sealing surface 6 at the gas outlet 5 end of the main valve 2, and pipeline decompression is realized.

Further, as another embodiment of the present invention, as shown in fig. 4 and 5, the gas inlet of the main valve 2 is defined as lower, the gas outlet 5 end of the main valve 2 is defined as upper, the gas outlet connector 30 is an upper valve cover, the main valve cover i 28 is a lower valve cover, the main valve cover ii 29 is an upper valve cover, the diaphragm chamber i 8 is a lower diaphragm chamber, and the diaphragm chamber ii 9 is an upper diaphragm chamber. In this embodiment, the closing spring 31 is disposed in the lower diaphragm chamber.

Further, as another embodiment of the present invention, the gas inlet of the main valve 2 is defined as left, and the gas outlet 5 of the main valve 2 is positioned right, so that the gas outlet connector 30 is a right valve cover, the main valve cover i 28 is a left valve cover, the main valve cover ii 29 is a middle valve cover, the diaphragm chamber i 8 is a left diaphragm chamber, and the diaphragm chamber ii 9 is a right diaphragm chamber. In this embodiment, the closing spring 31 is provided in the left diaphragm chamber.

Further, the return of the pilot valve 1: after the air of the high-pressure valve is filled in the air inlet cavity 14, the piston I24 is positioned at the highest position, the air in the air inlet cavity 14 simultaneously enters the discharge cavity 15 through the damping hole II 17 on the piston I24, the discharge cavity 15 directly discharges air outwards, when the air pressure of the main pipeline is instantaneously reduced after the main valve 2 is opened, the air inlet pressure is reduced, at the moment, the air entering the air inlet cavity 14 and the gas entering the discharge cavity are communicated under the action of the damping hole I21 and the damping hole II 17, the air pressure of the air inlet cavity 14 is rapidly reduced, and the piston I24 is rapidly pressed to return under the action of spring force; the pilot valve 1 completes one on-off cycle.

Return of main valve 2: meanwhile, a piston II 25 connected with a piston I24 is synchronously pressed back to the original position, a vulcanized valve seat 19 at the top of the piston II 25 is separated from a fixed nozzle 18, at the moment, an inlet of air P1 from the side is opened, at the same time, the return of the piston II 25 enables a sealing ring of the piston II 25 to move along with the movement and return to the position below a communication hole 23 communicated with a diaphragm cavity I8, at the moment, a diaphragm cavity I8 of a main valve 2 is communicated with a balance cavity 16, high-pressure air of a diaphragm cavity II 9 of the main valve 2 is communicated with the diaphragm cavity I8 through the balance cavity 16, the high-pressure air of the diaphragm cavity II 9 is instantly balanced with the diaphragm cavity I8 after the high-pressure air of the diaphragm cavity II 9 flows back, at the same time, the front-pressure air from the fixed nozzle 18 continuously fills the diaphragm cavity I8 and the diaphragm cavity II 9 of the main valve 2, the diaphragm cavity I8 and the diaphragm cavity II 9 of the main valve 2 are balanced in air pressure, and at the same time, a spring pushes a main valve 2 diaphragm 7 and a tray assembly 10 of the sliding sleeve 3 to rapidly press towards the upper limit position to be contacted with a sealing surface 6 on a gas outlet joint 30 of the main valve 2, so that the main valve 2 is reset is realized; the main valve 2 completes one opening and closing cycle.

The conventional safety valve has a structural limitation that the outlet discharge space has to change the fluid direction, such as discharging from the side at 90 °, and the flow channel forcibly changes the fluid direction during the discharging process, which may cause strong vibration of the safety valve, and may cause the pressure setting or other parts of the safety valve to be loosened during the vibration process, thereby causing a problem of reduced pressure control accuracy. The main valve 2 of the invention is an axial flow structure, and adopts a hollow sliding sleeve 3, the sliding sleeve 3 is coaxial with the gas inlet and the gas outlet 5, the change of the fluid direction is small in the discharging process, the vibration caused by the change of the fluid direction is large can be effectively solved, and the problems of component looseness, set pressure change and pressure control precision reduction caused by the vibration are solved.

Claims (4)

1. The main valve structure of the pilot axial flow type safety valve is characterized in that: a hollow sliding sleeve (3) and a diaphragm chamber (4) are arranged in the main valve, the hollow sliding sleeve (3) penetrates through the diaphragm chamber (4), and the outer wall of the sliding sleeve (3) is in sliding seal with the side walls of the upper end and the lower end of the diaphragm chamber (4); one end of the sliding sleeve (3) is in contact fit with a sealing surface (6) at the position corresponding to the gas outlet (5) in the main valve to form a sealing pair; a diaphragm (7) is fixedly arranged in the diaphragm chamber (4), and the diaphragm chamber (4) is divided into a diaphragm cavity I (8) and a diaphragm cavity II (9) by the diaphragm (7); the sliding sleeve (3) penetrates through the middle part of the diaphragm (7) and is fixed with the diaphragm (7) through the tray component (10); under the action of pressure difference between the diaphragm cavity I (8) and the diaphragm cavity II (9), the diaphragm (7) drives the sliding sleeve (3) to move.

2. The main valve structure of a pilot axial flow safety valve according to claim 1, wherein: the main valve includes that main mode lid I (28), main mode lid II (29) and gaseous outlet connection (30), form behind main mode lid I (28) and the flange joint of main mode lid II (29) diaphragm chamber (4), the gaseous import of main valve sets up on main mode lid I (28), and gaseous outlet connection (30) are installed on main mode lid II (29).

3. The main valve structure of a pilot axial flow safety valve according to claim 2, wherein: and the sliding sleeve (3) is in sliding seal with the main mould cover I (28) and the main mould cover II (29) respectively.

4. The main valve structure of a pilot axial flow safety valve according to any one of claims 1 to 3, wherein: a closing spring (31) is arranged in the diaphragm cavity I (8).

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