CN220792114U - Pressure relief pilot type gate valve - Google Patents

Abstract

The utility model discloses a pressure relief pilot type gate valve, which comprises a valve body, a valve cover, a valve rod and a gate plate, wherein an upstream flow channel and a downstream flow channel are arranged at two ends of the valve body; the valve body is internally provided with a pilot channel which is communicated with the downstream flow channel and the middle cavity and a pressure relief channel which is communicated with the upstream flow channel and the middle cavity, the pressure relief valve is arranged on the pressure relief channel, when the pressure of the middle cavity is not more than the pressure of the upstream flow channel, the pressure relief valve is closed, and when the pressure of the middle cavity is more than the pressure of the upstream flow channel, the pressure relief valve is opened and the middle cavity is communicated with the upstream flow channel. The utility model can effectively prevent abnormal boosting, realize gate valve depressurization opening and reduce valve rod operating force, thereby avoiding valve failure or serious accidents caused by abnormal boosting of the valve or closing of the gate plate which is blocked by too tight wedge.

Description

Pressure relief pilot type gate valve

Technical Field

The utility model relates to the technical field of valves, in particular to a pressure relief pilot type gate valve.

Background

The gate valve has the working principle that an operating element (such as a hand wheel, a speed reducer, a pneumatic device or an electric device and the like) arranged on the valve is used for driving a valve rod to lift, so that a closing element (a gate plate) is separated from a blocked runner orifice, and the flow of a pipeline medium is conducted or cut off. The through passage of the gate valve allows the medium to flow approximately straight through the valve, so that the flow resistance is small. Compared with a stop valve, a butterfly valve and a ball valve, the gate valve has a larger flow coefficient, and the flow performance is superior to that of the stop valve and the butterfly valve and is slightly inferior to that of the ball valve with the same specification.

The gate valve closure member is a plate-like member, also known as a gate or a gate plate. The structure forms include wedge type, single flat plate type and double plate gate valves; the wedge gate valve has a rigid single gate and a flexible gate. Various constructions of gate valves, particularly wedge gate valves, are most widely used. The wedge gate valve is suitable for various mounting modes and can be mounted on a horizontal pipeline, a vertical pipeline or an inclined pipeline so as to facilitate mounting, operation, maintenance and overhaul. The valve rod can be vertically upwards or horizontally installed, and can be reliably sealed in any installation mode.

The gate valve has two sealing surfaces, and when closed, the medium on the upstream and downstream of the pipeline is isolated. Meanwhile, part of medium is retained in the middle inner cavity area of the valve body sealed by the two sealing surfaces, the area is called a valve middle cavity, and the medium pressure is called middle cavity pressure.

As described above, the gate valve has two sealing surfaces, the sealing is reliable, and the opening and closing operation force is small. This is a significant advantage of gate valves. However, if the medium in the sealing surface plugging areas is liquid, when the temperature of the medium changes, the local liquid pressure is lower than the critical vaporization pressure, and the liquid vaporization can cause the pressure of the middle cavity to rise, which is called abnormal pressure rise.

The abnormal pressure rising hazard of the valve middle cavity is extremely large, the valve is leaked by a light person, the opening and closing part is blocked or stuck, and the functions of related parts (flashboard, valve seat, valve rod or driving part) are invalid or broken. The valve failure causes more cases and accidents, which can cause leakage, equipment bursting, casualties and system shutdown, and even peripheral community and city disastrous accidents-!

Disclosure of Invention

The utility model aims to provide a pressure relief pilot type gate valve, which can effectively prevent abnormal pressure rise, realize pressure reduction and opening of the gate valve and reduce the operating force of a valve rod, thereby avoiding valve failure or major accidents caused by abnormal pressure rise or closing of a gate plate due to overtightening wedge.

In order to achieve the above purpose, the present utility model provides the following technical solutions: the pressure relief pilot type gate valve comprises a valve body, a valve cover, a valve rod and a gate plate, wherein an upstream flow channel and a downstream flow channel are arranged at two ends of the valve body; the valve body is internally provided with a pilot channel for communicating the downstream flow channel with the middle cavity and a pressure relief channel for communicating the upstream flow channel with the middle cavity, the pressure relief valve is arranged on the pressure relief channel, when the pressure of the middle cavity is not more than the pressure of the upstream flow channel, the pressure relief valve is closed, and when the pressure of the middle cavity is more than the pressure of the upstream flow channel, the pressure relief valve is opened and conducts the middle cavity with the upstream flow channel.

The pressure relief valve is further arranged to comprise a first valve core, a first pressure relief spring, a second pressure relief spring, a first seat sleeve and a first gland, wherein a supporting step is arranged in the pressure relief channel, the first valve core and the first seat sleeve are arranged in the pressure relief channel in a sliding mode, the first gland is arranged at the upper end of the pressure relief channel and is used for limiting the first valve core and the first seat sleeve in the pressure relief channel, two ends of the first pressure relief spring respectively prop against the end face of the supporting step and the lower end of the first valve core, two ends of the second pressure relief spring respectively prop against the upper end of the first valve core and the lower end of the first seat sleeve, and a first flow passage used for communicating the pressure relief channel with the middle cavity is formed in the first seat sleeve; when the first valve core is separated from the first flow passage, the middle cavity is communicated with the upstream flow passage.

The first valve core comprises a pressure relief spring seat, a pressure relief screw rod and a pressure relief valve core main body, wherein the pressure relief spring seat is connected to the middle part of the pressure relief screw rod in a threaded mode, a first nut propped against the pressure relief spring seat is arranged on the pressure relief screw rod, and the pressure relief valve core main body is connected to the upper end of the pressure relief screw rod in a threaded mode.

The utility model is further characterized in that the outer periphery of the pressure relief spring seat is attached to the inner periphery of the pressure relief channel, and a plurality of first through holes which are vertically communicated are arranged on the pressure relief spring seat.

The utility model is further characterized in that the flashboard is provided with an inverted T-shaped groove, the valve rod is provided with a linkage block matched with the inverted T-shaped groove, a vertical movable gap is arranged between the linkage block and the inverted T-shaped groove, and the valve rod is also provided with a pressing plate for limiting the first seat sleeve to ascend when the gate valve is closed.

The pilot valve is further arranged on the pilot channel, the pilot valve comprises a second valve core, a first pilot spring, a second seat sleeve and a second gland, a sealing step is arranged in the pilot channel, the second valve core and the second seat sleeve are slidably arranged in the pilot channel, the second gland is arranged at the upper end of the pilot channel and is used for limiting the second valve core and the second seat sleeve in the pilot channel, two ends of the first pilot spring respectively prop against the end face of the sealing step and the lower end of the second valve core, two ends of the second pilot spring respectively prop against the upper end of the second valve core and the lower end of the second seat sleeve, and a second flow passage used for communicating the pilot channel with the middle cavity is formed in the second seat sleeve; when the gate valve is closed, the pressing plate abuts against the upper end of the second seat sleeve, and when the second valve core is separated from the sealing step, the middle cavity is communicated with the downstream flow channel.

The second valve core further comprises a pilot spring seat, a pilot screw rod and a pilot valve core main body, wherein the pilot spring seat is connected to the middle part of the pilot screw rod in a threaded mode, a second nut which abuts against the pilot spring seat is arranged on the pilot screw rod, and the pilot valve core main body is connected to the lower end of the pilot screw rod in a threaded mode.

The outer periphery of the pilot spring seat is attached to the inner periphery of the pilot channel, and a plurality of second through holes which penetrate up and down are formed in the pilot spring seat.

The utility model is further characterized in that the valve rod is further provided with a limit step, a thread section is arranged at the position, corresponding to the upper part of the limit step, of the valve rod, the pressing plate is sleeved on the periphery of the thread section, and the thread section is in threaded connection with a locking nut for pressing the pressing plate on the limit step.

Compared with the prior art, the utility model has the following technical effects: the gate valve is internally provided with two small valves, one is a pressure relief valve, and the other is a pilot valve. When the medium pressure in the middle cavity is abnormally increased during the closing period of the valve, the pressure relief valve is opened, and the medium flows back to the upstream flow passage of the valve to prevent abnormal pressure increase; when the valve is opened, the pressure relief valve and the pilot valve are opened before the main valve, so as to reduce the medium pressure difference at the moment of opening the main valve, thereby reducing the opening operation load of the main valve. Therefore, the utility model can effectively prevent abnormal pressure rise, realize the pressure reduction opening of the gate valve and reduce the valve rod operating force. Thereby avoiding valve failure or major accidents caused by abnormal pressure rise of the valve or closing of the tight wedge flashboard. And because the operation load is reduced, the flexibility of the valve is improved, the specification of a matched driving device is smaller, and the cost is low. The installation and maintenance are convenient, the overhaul period is long, and the service life is prolonged.

Drawings

FIG. 1 is a schematic view of the overall structure of the present utility model;

FIG. 2 is a schematic diagram of the mounting structure of the pressure relief valve and pilot valve of the present utility model;

FIG. 3 is an enlarged schematic view of the portion A in FIG. 2;

fig. 4 is an enlarged schematic view of the portion B in fig. 2.

In the figure: 1. a valve body; 2. a valve cover; 3. a valve stem; 4. a flashboard; 5. an upstream flow channel; 6. a downstream flow passage; 7. a middle cavity; 8. a valve seat; 9. a pressure release valve; 10. a pilot passage; 11. a pressure relief channel; 12. a first valve core; 13. a first pressure relief spring; 14. a second pressure relief spring; 15. a first sleeve; 16. a first gland; 17. a support step; 18. a first flow-through channel; 19. a pressure relief spring seat; 20. a pressure relief screw; 21. a pressure relief valve core body; 22. a first nut; 23. a first through hole; 24. an inverted T-shaped groove; 25. a linkage block; 26. a clearance gap; 27. a pressing plate; 28. a pilot valve; 29. a second valve core; 30. a first pilot spring; 31. a second pilot spring; 32. a second sleeve; 33. a second gland; 34. a sealing step; 35. a second flow-through channel; 36. a pilot spring seat; 37. a pilot screw; 38. a pilot spool body; 39. a second nut; 40. a second through hole; 41. a limit step; 42. a threaded section; 43. and (5) locking the nut.

Detailed Description

The following description of the embodiments of the present utility model will be made clearly and completely with reference to the accompanying drawings, in which it is apparent that the embodiments described are only some embodiments of the present utility model, but not all embodiments. All other embodiments, which can be made by those skilled in the art based on the embodiments of the utility model without making any inventive effort, are intended to be within the scope of the utility model.

Examples: the pressure relief pilot type gate valve as shown in the attached drawings 1-4 comprises a valve body 1, a valve cover 2, a valve rod 3 and a gate plate 4, wherein an upstream flow passage 5 and a downstream flow passage 6 are arranged at two ends of the valve body 1, the valve cover 2 is arranged at the upper part of the valve body 1, a middle cavity 7 is formed between the middle part of the valve body 1 and the valve cover 2, the valve rod 3 penetrates through the valve cover 2, the outer end of the valve rod 3 is connected with a driving device, the inner end of the valve rod 3 is connected with the gate plate 4 in a linkage manner, and a valve seat 8 is respectively arranged at positions corresponding to two sides of the gate plate 4 in the valve body 1; the gate valve further comprises a pressure relief valve 9, a pilot channel 10 which is used for communicating the downstream flow channel 6 with the middle cavity 7 and a pressure relief channel 11 which is used for communicating the upstream flow channel 5 with the middle cavity 7 are arranged in the valve body 1, the pressure relief valve 9 is arranged on the pressure relief channel 11, when the pressure of the middle cavity 7 is not more than the pressure of the upstream flow channel 5, the pressure relief valve 9 is closed, and when the pressure of the middle cavity 7 is more than the pressure of the upstream flow channel 5, the pressure relief valve 9 is opened and conducts the middle cavity 7 with the upstream flow channel 5.

As shown in fig. 2 and fig. 3, the pressure release valve 9 includes a first valve core 12, a first pressure release spring 13, a second pressure release spring 14, a first seat cover 15 and a first gland 16, a support step 17 is disposed in the pressure release channel 11, the first valve core 12 and the first seat cover 15 are slidably disposed in the pressure release channel 11, a first sealing ring is disposed between the first seat cover 15 and the pressure release channel 11, the first gland 16 is mounted at the upper end of the pressure release channel 11 and is used for limiting the first valve core 12 and the first seat cover 15 in the pressure release channel 11, two ends of the first pressure release spring 13 respectively abut against the end face of the support step 17 and the lower end of the first valve core 12, two ends of the second pressure release spring 14 respectively abut against the upper end of the first valve core 12 and the lower end of the first seat cover 15, and a first through-flow channel 18 for communicating the pressure release channel 11 with the middle cavity 7 is formed on the first seat cover 15; when the first spool 12 is disengaged from the first flow passage 18, the intermediate chamber 7 communicates with the upstream flow passage 5. The first valve core 12 comprises a pressure relief spring seat 19, a pressure relief screw rod 20 and a pressure relief valve core main body 21, wherein the pressure relief spring seat 19 is in threaded connection with the middle of the pressure relief screw rod 20, a first nut 22 which is abutted against the pressure relief spring seat 19 is arranged on the pressure relief screw rod 20, and the pressure relief valve core main body 21 is in threaded connection with the upper end of the pressure relief screw rod 20. The periphery of the pressure relief spring seat 19 is attached to the inner periphery of the pressure relief channel 11, and a plurality of first through holes 23 penetrating up and down are arranged on the pressure relief spring seat 19.

As shown in fig. 2, the gate plate 4 is provided with an inverted T-shaped groove 24, the valve rod 3 is provided with a linkage block 25 matched with the inverted T-shaped groove 24, a vertical movable gap 26 is arranged between the linkage block 25 and the inverted T-shaped groove 24, and the valve rod 3 is also provided with a pressing plate 27 for limiting the first seat cover 15 to ascend when the gate valve is closed. The valve rod 3 is further provided with a limit step 41, a thread section 42 is arranged at a position, corresponding to the upper side of the limit step 41, of the valve rod 3, the pressing plate 27 is sleeved on the periphery of the thread section 42, and a locking nut 43 used for pressing the pressing plate 27 on the limit step 41 is connected to the thread section 42 in a threaded mode.

As shown in fig. 2 and fig. 4, the pilot valve 28 is mounted on the pilot channel 10, the pilot valve 28 includes a second valve core 29, a first pilot spring 30, a second pilot spring 31, a second seat cover 32 and a second gland 33, a sealing step 34 is disposed in the pilot channel 10, the second valve core 29 and the second seat cover 32 are slidably disposed in the pilot channel 10, a sealing ring is disposed between the second seat cover 32 and the pilot channel 10, the second gland 33 is mounted at the upper end of the pilot channel 10 and is used for limiting the second valve core 29 and the second seat cover 32 in the pilot channel 10, two ends of the first pilot spring 30 respectively abut against the end face of the sealing step 34 and the lower end of the second valve core 29, two ends of the second pilot spring 31 respectively abut against the upper end of the second valve core 29 and the lower end of the second seat cover 32, and a second flow passage 35 for communicating the pilot channel 10 with the middle cavity 7 is disposed on the second seat cover 32; when the gate valve is closed, the pressing plate 27 abuts against the upper end of the second seat sleeve 32, and when the second valve core 29 is separated from the sealing step 34, the middle cavity 7 is communicated with the downstream flow channel 6. The second valve core 29 includes a pilot spring seat 36, a pilot screw rod 37, and a pilot valve core main body 38, the pilot spring seat 36 is screwed to the middle part of the pilot screw rod 37, the pilot screw rod 37 is provided with a second nut 39 abutted against the pilot spring seat 36, and the pilot valve core main body 38 is screwed to the lower end of the pilot screw rod 37. The outer periphery of the pilot spring seat 36 is attached to the inner periphery of the pilot passage 10, and a plurality of second through holes 40 penetrating up and down are provided in the pilot spring seat 36.

Wherein the sealing direction of the pressure relief valve 9 and the pilot valve 28 is opposite. When the gate valve is closed, the pressing plate 27 is in contact with the first seat sleeve 15 of the pressure relief valve 9 and the second seat sleeve 32 of the pilot valve 28 along with the movement of the valve rod 3, the valve rod 3 continues to push the gate plate 4 to the closed position, and springs in the pressure relief valve 9 and the pilot valve 28 are compressed by h0. A movable gap 26h is designed between the linkage block 25 of the valve rod 3 and the T-shaped groove of the flashboard 4, and h is more than or equal to h0.

The medium pressure of the upstream flow passage 5 of the gate valve is recorded as P1, the medium pressure of the downstream flow passage 6 is recorded as P2, and the pressure of the valve middle cavity 7 is recorded as Pc.

When Pc is less than or equal to P1, the gate valve is in a normal state, and abnormal boosting is performed once the condition that Pc is more than P1 occurs; pc P1, accidents may occur. The sealing area of the valve ports of the pressure relief valve 9 and the pilot valve 28 is set as a, the spring stiffness in the pressure relief valve 9 is set as S1, and the spring stiffness in the pilot valve 28 is set as S2. The aim of this solution is to try to avoid Pc not more than P1, as much as possible, pc P1. For this, the following analysis and design were performed.

i. For the relief valve 9:

when the gate valve is closed, the pressure plate 27 applies f1=s1h0+fm1 (1) to the relief valve 9

Fm1 is the friction force between the first sealing ring and the first seat cover 15 in the pressure relief valve 9

The pressure relief valve 9 is sealed under the condition that S1h0 is not less than (Pc-P1) a (2)

Let p= (Pc-P1), p be the gate valve cavity 7 overpressure value

It is clear that the smaller p, the more desirable it is to prevent overpressure. Fm1 is related to P, the smaller the pressing force required for the first seal ring. The spring in the pressure release valve 9 is properly designed, the rigidity S1 is smaller, the overpressure value delta P of the middle cavity 7 is smaller, and abnormal pressure rise of the middle cavity 7 can be effectively prevented.

According to formula (2), a smaller DeltaP value is set, the diameter of the built-in valve hole is set, and the corresponding spring stiffness in the pressure relief valve 9 is designed.

In general, pc=p1. During the closing of the gate valve, if the medium chamber 7 has overpressure (Pc & gtP 1) under the set condition, the medium pressure of the medium chamber 7 pushes the first valve core 12 to be separated from the first seat sleeve 15, and part of medium in the medium chamber 7 is immediately led back to the upstream flow passage 5 of the valve, so that the abnormal overpressure of the valve is prevented. When Pc is lowered to P1, the first valve core 12 is in contact sealing with the first seat sleeve 15 again under the action of spring force, so that the switching cycle action of the pressure release valve 9 is completed.

During closing of the gate valve, the relief valve 9 remains balanced, pc P1, under the force of the pressure plate 27, the spring force and the medium pressure.

When the gate valve is opened, the pressing plate 27 releases the acting force F1 to the first seat cover 15, and the spring in the relief valve 9 makes the first seat cover 15 and the first valve core 12 tend to be disengaged. The first seat 15 is out of contact with the first valve core 12 and the medium immediately enters the intermediate chamber 7 through the relief valve 9.

ii. For pilot valve 28:

when the gate valve is closed, the force of the pressing plate 27 on the pilot valve 28 is f2=s2h0+fm2 (3)

Fm2 is the friction between the second seal ring in the pilot valve 28 and the second sleeve 32. The pilot valve 28 has a second sealing ring in the region of the pressure Pc, the second sealing ring being limited to guiding, the required pressing force of the second sealing ring being small, so that Fm2 is small. That is, the force F2 of the pressure plate 27 against the pilot valve 28 acts substantially to compress the spring in the pilot valve 28.

The second spool 29 in the pilot valve 28 closes under the medium force (Pc-P2) a and the spring force S2h0, blocking the medium leakage of the intermediate chamber 7 to the downstream flow passage 6.

During closing of the gate valve, pilot valve 28 closes and remains sealed under the force of pressure plate 27, spring force and media pressure.

When the gate valve is opened, the pressing plate 27 releases the acting force F2 on the second seat cover 32, and the spring in the pilot valve 28 enables the second valve core 29 to be separated from the sealing surface of the pilot valve 28.

The condition for opening the pilot valve 28 is that S2h0 is equal to or greater than (Pc-P2) a (4)

In general, p2=0, pc=p1,

s2h 0. Gtoreq. (P1) a

The internal valve orifice diameter is set according to equation (4), and the stiffness of the spring within pilot valve 28 is properly designed. The opening moment of the gate valve can be ensured, the pilot valve 28 is firstly opened, and part of medium in the middle cavity 7 is immediately discharged to the gate valve outlet channel, so that the opening pressure difference is reduced.

Wherein the spring in the relief valve 9 has a smaller stiffness and the spring in the pilot valve 28 has a larger stiffness. The spring in the relief valve 9 and the spring in the pilot valve 28 are connected in series by two sections respectively to realize that the corresponding valve core is out of contact with the seat cover or the corresponding valve core is out of contact with the sealing surface. The spring compression h0, the pressure relief valve 9 and the pilot valve 28 obtain initial sealing force; the clearance h between the valve rod 3 and the flashboard 4 and the compression amount h0 of the spring provide preconditions for the valve cores of the pressure relief valve 9 and the pilot valve 28 to separate from the sealing surfaces when the gate valve is opened.

A gate valve with a built-in relief valve 9 and a pilot valve 28, the relief valve 9 being capable of preventing abnormal pressure rise of the middle chamber 7 during valve closing; when the gate valve is opened, the pressure release valve 9 and the pilot valve 28 are simultaneously opened before the main valve, and medium in the upstream flow passage 5 flows to the downstream flow passage 6 through the middle cavity 7, so that the pressure difference between the front side and the rear side of the main valve is reduced. The valve opening operation force is reduced, the friction and abrasion of the sealing surface are reduced, and the service life is prolonged.

The three-valve of the gate valve is integrated, the pressure relief valve 9 and the pilot valve 28 are arranged above the inner cavity channel of the gate valve, the strength and rigidity of the gate valve 1 are enhanced, two built-in valve bodies 1 are not needed to be additionally arranged, the built-in valve is omitted, and the cost is reduced.

Claims (9)

1. The pressure relief pilot type gate valve comprises a valve body (1), a valve cover (2), a valve rod (3) and a gate plate (4), wherein an upstream flow channel (5) and a downstream flow channel (6) are arranged at two ends of the valve body (1), the valve cover (2) is arranged on the upper part of the valve body (1), a middle cavity (7) is formed between the middle part of the valve body (1) and the valve cover (2), the valve rod (3) penetrates through the valve cover (2), the inner end of the valve rod (3) is connected with the gate plate (4) in a linkage manner, and a valve seat (8) is respectively arranged at positions corresponding to two sides of the gate plate (4) in the valve body (1); the method is characterized in that: still include relief valve (9), be equipped with in valve body (1) with downstream runner (6) and middle chamber (7) guide passageway (10) that are linked together and with pressure release passageway (11) that upstream runner (5) are linked together with middle chamber (7), relief valve (9) are installed on pressure release passageway (11), and when middle chamber (7) pressure was not more than upstream runner (5) pressure, relief valve (9) were closed, and when middle chamber (7) pressure was more than upstream runner (5) pressure, relief valve (9) were opened and with middle chamber (7) and upstream runner (5) switch on.

2. The pressure relief pilot gate valve of claim 1, wherein: the pressure relief valve (9) comprises a first valve core (12), a first pressure relief spring (13), a second pressure relief spring (14), a first seat sleeve (15) and a first gland (16), wherein a supporting step (17) is arranged in the pressure relief channel (11), the first valve core (12) and the first seat sleeve (15) are slidably arranged in the pressure relief channel (11), the first gland (16) is arranged at the upper end of the pressure relief channel (11) and used for limiting the first valve core (12) and the first seat sleeve (15) in the pressure relief channel (11), two ends of the first pressure relief spring (13) respectively prop against the end face of the supporting step (17) and the lower end of the first valve core (12), two ends of the second pressure relief spring (14) respectively prop against the upper end of the first valve core (12) and the lower end of the first seat sleeve (15), and a first through channel (18) used for communicating the pressure relief channel (11) with the middle cavity (7) is formed in the first seat sleeve (15); when the first valve core (12) is separated from the first through flow channel (18), the middle cavity (7) is communicated with the upstream flow channel (5).

3. The pressure relief pilot gate valve of claim 2, wherein: the first valve core (12) comprises a pressure relief spring seat (19), a pressure relief screw rod (20) and a pressure relief valve core main body (21), wherein the pressure relief spring seat (19) is in threaded connection with the middle of the pressure relief screw rod (20), a first nut (22) which is tightly propped against the pressure relief spring seat (19) is arranged on the pressure relief screw rod (20), and the pressure relief valve core main body (21) is in threaded connection with the upper end of the pressure relief screw rod (20).

4. The pressure relief pilot gate valve of claim 3, wherein: the periphery of pressure release spring holder (19) is laminated with pressure release passageway (11) inner periphery mutually to be equipped with a plurality of first through-holes (23) that link up from top to bottom on pressure release spring holder (19).

5. The pressure relief pilot gate valve of claim 2, wherein: be equipped with on flashboard (4) and fall T-shaped groove (24), be equipped with on valve rod (3) with fall T-shaped groove (24) matched with linkage piece (25), and be equipped with vertical clearance (26) between linkage piece (25) and the fall T-shaped groove (24), still install on valve rod (3) and be used for restriction first seat cover (15) clamp plate (27) that go upward when the gate valve is closed.

6. The pressure relief pilot gate valve of claim 5, wherein: the pilot valve (28) is mounted on the pilot channel (10), the pilot valve (28) comprises a second valve core (29), a first pilot spring (30), a second pilot spring (31), a second seat cover (32) and a second gland (33), a sealing step (34) is arranged in the pilot channel (10), the second valve core (29) and the second seat cover (32) are slidably arranged in the pilot channel (10), the second gland (33) is mounted at the upper end of the pilot channel (10) and is used for limiting the second valve core (29) and the second seat cover (32) in the pilot channel (10), two ends of the first pilot spring (30) are respectively abutted against the end face of the sealing step (34) and the lower end of the second valve core (29), two ends of the second pilot spring (31) are respectively abutted against the upper end of the second valve core (29) and the lower end of the second seat cover (32), and a second channel (35) for communicating the pilot channel (10) with the middle cavity (7) is formed in the second seat cover (32); when the gate valve is closed, the pressing plate (27) is abutted against the upper end of the second seat sleeve (32), and when the second valve core (29) is separated from the sealing step (34), the middle cavity (7) is communicated with the downstream flow channel (6).

7. The pressure relief pilot gate valve of claim 6, wherein: the second valve core (29) comprises a pilot spring seat (36), a pilot screw rod (37) and a pilot valve core main body (38), wherein the pilot spring seat (36) is connected to the middle of the pilot screw rod (37) in a threaded mode, a second nut (39) which abuts against the pilot spring seat (36) is arranged on the pilot screw rod (37), and the pilot valve core main body (38) is connected to the lower end of the pilot screw rod (37) in a threaded mode.

8. The pressure relief pilot gate valve of claim 7, wherein: the outer periphery of the pilot spring seat (36) is attached to the inner periphery of the pilot channel (10), and a plurality of second through holes (40) penetrating up and down are formed in the pilot spring seat (36).

9. The pressure relief pilot gate valve of claim 5, wherein: the valve rod (3) is further provided with a limit step (41), a thread section (42) is arranged at the position, corresponding to the upper part of the limit step (41), of the valve rod (3), the pressing plate (27) is sleeved on the periphery of the thread section (42), and a locking nut (43) used for pressing the pressing plate (27) on the limit step (41) is connected to the thread section (42) in a threaded mode.