Explosion-proof valve with compensation sealing structure

Abstract

The utility model discloses an explosion-proof valve with a compensation sealing structure, which comprises a valve body, a front end cover arranged on the valve body, a pilot head component arranged on the front end cover, a valve cavity arranged between the valve body and the front end cover, a spacer bush component arranged in the valve body, a valve rod movably arranged in the spacer bush component, a large piston arranged in the front cavity and a large piston arranged in the rear cavity. The valve rod abuts against the large piston, the interior of the valve rod is hollow, a gas channel is formed in the valve rod, the front end of the spacer bush assembly is provided with an annular protrusion A and an annular protrusion B, the annular protrusion A and the annular protrusion B are matched to form a mounting groove, the outer wall of the annular protrusion A is sleeved with a sealing ring A, a sealing ring B and a sealing ring C are arranged in the mounting groove, and the outer wall of the sealing ring C is sleeved with the sealing ring B in the radial direction. The sealing ring B always has the movement trend of hooping the sealing ring C, the inner wall of the sealing ring C is in sealing fit with the outer wall of the valve rod, the sealing performance is good, gas is not prone to leakage, the valve rod response speed is high, and the service life is long.

Description

Technical Field

[0001] The utility model relates to the technical field of explosion-proof valves, in particular to an explosion-proof valve with a compensating sealing structure. Background Art

[0002] In the industrial field, the five-way valve is a common fluid control device. The flameproof five-way valve is based on the ordinary five-way valve and has a flameproof design. It can meet the safety requirements of flammable and explosive media systems. It is mainly composed of a valve body, a front cover, a rear cover, a spacer assembly and a valve stem. The spacer assembly is arranged in the valve body, and the valve stem is arranged in the spacer assembly. The valve stem divides the valve cavity into a front cavity and a rear cavity, and the fluid switch control is realized by the movement of the valve stem. Usually, there are exhaust holes on the front cover and the rear cover of the valve body. When the valve stem moves, the excess gas in the front cavity or the rear cavity is discharged through the exhaust hole, thereby improving the response speed of the valve stem. However, this design has certain defects, the sealing effect is not good, and impurities are easy to enter the valve body through the exhaust hole, affecting the use. Secondly, the movement of the conventional valve stem is usually controlled by the spring force, but in the long-term use process, the spring is prone to fatigue, resulting in a shortened life of the valve stem; in addition, in order to improve the sealing performance, a sealing structure is usually provided between the valve stem and the spacer assembly, but in the process of the valve stem moving, it is easy to cause wear to the sealing structure, affecting the performance and service life of the valve, so it is necessary to improve it. Utility Model Content

[0003] The utility model aims to provide a flameproof valve with a compensating sealing structure in view of the defects and shortcomings of the prior art, which has a simple and reasonable structure, convenient operation, good sealing performance, gas is not easy to leak, the valve stem responds quickly and has a long service life.

[0004] In order to achieve the above purpose, the utility model adopts the following technical solutions:

[0005] The utility model discloses an explosion-proof valve with a compensating sealing structure, comprising a valve body, a front end cover is provided at the front end of the valve body, a pilot head assembly is provided on the front end cover, a valve cavity is provided between the valve body and the front end cover, a spacer assembly is fixedly provided in the valve body, a valve stem is movably provided in the spacer assembly, the valve stem divides the valve cavity into a front cavity and a rear cavity, a large piston is provided in the front cavity, the front end of the valve stem is abutted against the large piston, a gas channel is provided in the internal hollow of the valve stem, the gas channel is used to connect the front cavity and the rear cavity, an annular protrusion A and an annular protrusion B are provided at the front end of the spacer assembly, an installation groove is formed between the annular protrusion A, a sealing ring A which is sealed with the valve body is provided on the outer wall of the annular protrusion A, a sealing ring B and a sealing ring C are provided in the installation groove, the sealing ring B is radially sleeved on the outer wall of the sealing ring C, the sealing ring B always has a movement tendency to tighten the sealing ring C, and the inner wall of the sealing ring C is sealed with the outer wall of the valve stem.

[0006] Furthermore, the valve body is provided with an air inlet, a first exhaust port, a second exhaust port, a first working port and a second working port, an air inlet channel A is formed between the air inlet and the front cavity, and an air inlet channel B is formed between the air inlet and the rear cavity, the pilot head assembly is used to control the opening or closing of the air inlet channel A, and the valve stem moves in the spacer sleeve assembly under the action of the air pressure difference between the front cavity and the rear cavity, thereby controlling the air path switching between the air inlet, the first exhaust port, the second exhaust port, the first working port and the second working port.

[0007] Furthermore, a small piston portion is fixedly provided at the rear end of the valve stem, and the cross-sectional area of ​​the small piston portion is smaller than the cross-sectional area of ​​the large piston. The small piston portion divides the rear chamber into chamber A and chamber B, and the large piston divides the front chamber into chamber C and chamber D. The air intake channel A is connected to chamber D, and the air intake channel B is connected to chamber A.

[0008] Furthermore, an air hole is provided on the rear end of the valve stem, and the air hole is respectively connected to the gas channel and chamber B. The front end of the valve stem is provided with a groove portion that cooperates with the large piston, and the groove portion is respectively connected to the gas channel and chamber C.

[0009] Furthermore, the pilot head assembly includes a base, a sleeve seat and a coil, the lower end of the base is fixedly connected to the front end cover, the upper end of the base is fixedly connected to the sleeve seat, the coil is fixedly arranged on the outer periphery of the sleeve seat, a static iron core and a moving iron core are arranged in the sleeve seat, the static iron core is fixedly arranged in the sleeve seat, the moving iron core is movably arranged below the static iron core, an exhaust passage is arranged in the hollow interior of the static iron core, a plug A is arranged at the upper end of the moving iron core for sealing cooperation with the exhaust passage, a plug B is arranged at the lower end of the moving iron core for sealing cooperation with the intake passage A, and a small spring is also arranged between the lower end of the moving iron core and the base.

[0010] Furthermore, a receiving space is provided in the hollow interior of the moving iron core, and a spring is provided in the receiving space. The upper end of the spring abuts against the plug A, and the lower end of the spring abuts against the plug B.

[0011] Furthermore, the sealing ring A is an O-type sealing ring, the sealing ring B is a C-type sealing ring, the sealing ring C is a T-type sealing ring, and the inner wall of the T-type sealing ring is provided with a sealing portion protruding outward along the circumferential direction, and the sealing portion is sealed with the outer wall of the valve stem.

[0012] Furthermore, a plurality of outwardly protruding portions are provided at intervals on the valve stem, and the protruding portions are in sealing cooperation with the sealing portion.

[0013] Furthermore, a special-shaped sealing ring is provided for sealing between the spacer assembly and the front end cover.

[0014] Furthermore, a Y-shaped sealing ring is sealed between the large piston and the front end cover, and a V-shaped opening of the Y-shaped sealing ring faces the spacer assembly.

[0015] The beneficial effects of the utility model are as follows: the explosion-proof valve with a compensating sealing structure described in the utility model can facilitate the rapid movement of the valve stem and improve the response speed by setting a gas channel. The spacer assembly is sealed with a sealing ring A, a sealing ring B and a sealing ring C. The sealing ring A is an O-ring with good sealing performance to prevent gas leakage between the spacer assembly and the valve body. The sealing ring B is a C-ring, and the sealing ring C is a T-ring with good sealing performance to effectively prevent gas leakage. The T-ring has good elasticity and vibration reduction capabilities. The C-ring can provide elastic force for the T-ring, which is beneficial to the resetting of the T-ring. The inner wall of the T-ring is provided with a sealing portion protruding outward along the circumferential direction. The sealing portion is sealed with the outer wall of the valve stem. The design of the sealing portion can increase the contact area, improve the sealing effect, and effectively disperse the pressure on the contact surface to slow down the wear rate. When the valve stem moves, the T-ring is subjected to force to overcome the elastic force of the C-ring and expand outward to adapt to the movement of the valve stem.

[0016] Conventional valve stem movement is usually controlled by spring force, but the spring is prone to fatigue during long-term use, resulting in a shortened life of the valve stem. The utility model drives the valve stem to move through the air pressure difference between the front cavity and the rear cavity, eliminates the spring, thereby reducing the risk of short life of the loaded mechanical parts and making the movement of the valve stem smoother.

[0017] The working principle of the utility model is as follows: after the air enters the air inlet, it flows through the air inlet channel A and the air inlet channel B respectively. When the pilot head assembly is not powered on, the air inlet channel A is closed, and the gas enters the rear chamber through the air inlet channel B. At this time, the pressure in the rear chamber is greater than that in the front chamber, pushing the valve stem to move to the first working position. At this time, the air inlet is connected to the first working port, and the second working port is connected to the second exhaust port. The gas in chamber B quickly enters chamber C through the gas channel, thereby improving the response speed of the valve stem; when the pilot head assembly is powered on, the air inlet channel A is opened. At this time, the gas enters the front chamber through the air inlet channel A. The gas enters the front cavity through the air inlet channel B, and also enters the rear cavity through the air inlet channel B. The force of the gas on the small piston is the gas pressure multiplied by the cross-sectional area of ​​the small piston, and the force of the gas on the large piston is the gas pressure multiplied by the cross-sectional area of ​​the large piston. Since the cross-sectional area of ​​the small piston is smaller than that of the large piston, the pressure in the front cavity is greater than that in the rear cavity, pushing the valve stem to move to the second station. At this time, the air inlet is connected with the second working port, and the first working port is connected with the first exhaust port. The gas in chamber C quickly enters chamber B through the gas channel, thereby improving the response speed of the valve stem. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 It is a schematic diagram of the overall structure of the utility model in the first viewing angle;

[0019] Figure 2 It is a schematic diagram of the overall structure of the utility model under a second viewing angle;

[0020] Figure 3 This is a schematic diagram of the cross-sectional structure of the valve stem of the utility model in the first working position;

[0021] Figure 4 It is a schematic diagram of the cross-sectional structure of the valve stem of the utility model in the second working position;

[0022] Figure 5 is a schematic diagram of the cross-sectional structure of the utility model at a third viewing angle;

[0023] Figure 6 yes Figure 5 A schematic diagram of the enlarged structure at A in the middle;

[0024] Figure 7 is a schematic diagram of the cross-sectional structure of the utility model at a fourth viewing angle;

[0025] Figure 8 is a schematic diagram of the cross-sectional structure of the utility model at a fifth viewing angle;

[0026] Fig. 9 It is a structural diagram of the valve stem.

[0027] Figure 1-9 Middle: 1. Valve body; 2. Pilot head assembly; 3. Spacer assembly; 4. Valve stem; 5. Large piston; 6. Gas channel; 7. Annular protrusion A; 8. Annular protrusion B; 9. Mounting groove; 10. Air inlet; 11. First exhaust port; 12. Second exhaust port; 13. First working port; 14. Second working port; 15. Air inlet channel A; 16. Air inlet channel B; 17. Small piston; 18. Chamber A; 19. Chamber B; 20. Chamber C; 21. Chamber D; 22. Air hole; 23 , groove part; 24, sleeve seat; 25, coil; 26, base; 27, static iron core; 28, moving iron core; 29, exhaust channel; 30, plug A; 31, plug B; 32, accommodating space; 33, spring; 34, sealing ring A; 35, sealing ring B; 36, sealing ring C; 37, raised part; 38, sealing part; 39, special-shaped sealing ring; 40, Y-shaped sealing ring; 41, valve port; 42, front end cover; 43, sealing ring D; 44, small spring; 45, annular protrusion C. DETAILED DESCRIPTION

[0028] The utility model is further described below in conjunction with the accompanying drawings.

[0029] like Figure 1-9The explosion-proof valve with a compensating sealing structure shown in the figure comprises a valve body 1, a front end cover 42 is provided at the front end of the valve body 1, a pilot head assembly 2 is provided on the front end cover 42, a valve cavity is provided between the valve body 1 and the front end cover 42, a spacer assembly 3 is fixedly provided in the valve body 1, a valve stem 4 is movably provided in the spacer assembly 3, the spacer assembly 3 is beneficial to reduce the wear between the valve stem 4 and the valve body 1, prolong the service life, and can further improve the sealing performance and prevent gas leakage, the valve stem 4 divides the valve cavity into a front cavity and a rear cavity, a large piston 5 is provided in the front cavity, the front end of the valve stem 4 is against the large piston 5, a gas channel 6 is provided in the hollow interior of the valve stem 4, the gas channel 6 is used to connect the front cavity and the rear cavity, and the gas channel 6 is arranged along the length direction of the valve stem 4. By arranging the gas channel 6, the valve stem 4 can be easily moved quickly and the response speed can be improved, see Figure 6 The front end of the spacer assembly 3 is provided with an annular protrusion A7 and an annular protrusion B8, and an installation groove 9 is formed between the annular protrusion A7 and the annular protrusion B8. The outer wall of the annular protrusion A7 is provided with a sealing ring A34 that is sealed with the valve body 1. The installation groove 9 is provided with a sealing ring B35 and a sealing ring C36. The sealing ring B35 is radially sleeved on the outer wall of the sealing ring C36, and the sealing ring B35 always has a movement tendency to tighten the sealing ring C36. Specifically, the outer wall of the sealing ring B35 is tightly fitted with the inner wall of the installation groove 9, and the inner wall of the sealing ring B35 is tightly fitted with the outer wall of the sealing ring C36, which is beneficial to improve the sealing performance and prevent the sealing ring C36 from loosening during use. The inner wall of the sealing ring C36 is sealed with the outer wall of the valve stem 4.

[0030] Preferably, in this embodiment, the sealing ring A34 is an O-ring with good sealing performance, the sealing ring B35 is a C-ring with good sealing performance, which can effectively prevent gas leakage, and the sealing ring C36 is a T-ring, which has good elasticity and vibration reduction capabilities. The C-ring can provide elastic force for the T-ring, which is beneficial to the resetting of the T-ring. The inner wall of the T-ring is provided with a sealing portion 38 protruding outward along the circumferential direction. The sealing portion 38 is sealed with the outer wall of the valve stem 4. The design of the sealing portion 38 can increase the contact area and achieve better sealing effect. It can also effectively disperse the pressure on the contact surface and slow down the wear rate.

[0031] Preferably, in this embodiment, a plurality of outwardly protruding protrusions 37 are provided at intervals on the valve stem 4, and the protrusions 37 are sealed with the sealing portion 38. When the valve stem 4 moves, the T-shaped sealing ring is subjected to force to overcome the elastic force of the C-shaped sealing ring and expand outward to adapt to the movement of the valve stem 4.

[0032] Preferably, there are several spacer assemblies 3, which are axially connected in series on the outside of the valve stem 4 in sequence. The rear end of the spacer assembly 3 is provided with an annular protrusion C45. The annular protrusion C45 of the previous spacer assembly 3 cooperates with the annular protrusion B8 of the subsequent spacer assembly 3, so that the sealing ring C36 is axially limited between the annular protrusion C45 and the annular protrusion B8. When the valve stem 4 moves, the sealing ring C36 is not easily displaced by force.

[0033] Preferably, in this embodiment, the valve body 1 is provided with an air inlet 10, a first exhaust port 11, a second exhaust port 12, a first working port 13 and a second working port 14, see Figure 7 An air intake passage A15 is formed between the air intake port 10 and the front cavity, and an air intake passage B16 is formed between the air intake port 10 and the rear cavity. The pilot head assembly 2 is used to control the opening or closing of the air intake passage A15. The valve stem 4 moves in the spacer assembly 3 under the action of the air pressure difference between the front cavity and the rear cavity, thereby controlling the air path switching between the air intake port 10, the first exhaust port 11, the second exhaust port 12, the first working port 13 and the second working port 14. The movement of the conventional valve stem 4 is usually controlled by the force of the spring 33, but the spring 33 is prone to fatigue during long-term use, resulting in a shortened life of the valve stem 4. The utility model drives the valve stem 4 to move by the air pressure difference between the front cavity and the rear cavity, eliminates the spring 33, thereby reducing the risk of short life of the loaded mechanical parts, and can also make the movement of the valve stem 4 more stable.

[0034] Preferably, in this embodiment, a small piston portion 17 is fixedly provided at the rear end of the valve stem 4. Specifically, the small piston portion 17 is integrally formed with the valve stem 4. The cross-sectional area of ​​the small piston portion 17 is smaller than the cross-sectional area of ​​the large piston 5. The small piston portion 17 divides the rear chamber into chamber A18 and chamber B19, and the large piston 5 divides the front chamber into chamber C20 and chamber D21. The air inlet channel A15 is connected to the chamber D21, and the air inlet channel B16 is connected to the chamber A18. A sealing ring D43 is also sealed between the small piston portion 17 and the inner wall of the valve body 1 to effectively prevent gas leakage.

[0035] Specifically, after the air enters the air inlet 10, it flows through the air inlet channel A15 and the air inlet channel B16 respectively. When the pilot head assembly 2 is not powered on, the air inlet channel A15 is closed, and the gas enters the rear chamber through the air inlet channel B16. At this time, the pressure in the rear chamber is greater than that in the front chamber, pushing the valve stem 4 to move to the first position. Figure 3At this time, the air inlet 10 is connected to the first working port 13, and the second working port 14 is connected to the second exhaust port 12. When the pilot head assembly 2 is powered on, the air inlet channel A15 is opened. At this time, the gas enters the front chamber through the air inlet channel A15, and also enters the rear chamber through the air inlet channel B16. The force of the gas on the small piston part 17 is the gas pressure multiplied by the cross-sectional area of ​​the small piston part 17, and the force of the gas on the large piston 5 is the gas pressure multiplied by the cross-sectional area of ​​the large piston 5. Since the cross-sectional area of ​​the small piston part 17 is smaller than the cross-sectional area of ​​the large piston 5, the pressure in the front chamber is greater than that in the rear chamber, pushing the valve stem 4 to move to the second position, see Figure 4 At this time, the air inlet 10 is connected to the second working port 14 , and the first working port 13 is connected to the first exhaust port 11 .

[0036] Preferably, in this embodiment, refer to Fig. 9 The rear end of the valve stem 4 is provided with an air hole 22, and the air hole 22 is respectively connected with the gas channel 6 and the chamber B19. The front end of the valve stem 4 is provided with a groove portion 23 that cooperates with the large piston 5. The groove portion 23 is respectively connected with the gas channel 6 and the chamber C20. When the valve stem 4 moves to the first position, the gas in the chamber B19 quickly enters the chamber C20 through the gas channel 6. When the valve stem 4 moves to the second position, the gas in the chamber C20 quickly enters the chamber B19 through the gas channel 6, thereby improving the response speed of the valve stem 4.

[0037] Preferably, in this embodiment, refer to Figure 8The pilot head assembly 2 includes a base 26, a sleeve seat 24 and a coil 25. The lower end of the base 26 is fixedly connected to the front end cover 42, and the upper end of the base 26 is fixedly connected to the sleeve seat 24. The coil 25 is fixedly arranged on the outer periphery of the sleeve seat 24. A shell is arranged outside the coil 25. The shell has high explosion-proof performance and can meet the safety requirements of flammable and explosive medium systems. A static iron core 27 and a moving iron core 28 are arranged in the sleeve seat 24. The static iron core 27 is fixed in the sleeve seat 24, and the moving iron core 28 is movably arranged below the static iron core 27. An exhaust passage 29 is arranged in the hollow interior of the static iron core 27. A plug A30 is provided at the upper end of the moving iron core 28 for sealing with the exhaust passage 29, and a plug B31 is provided at the lower end of the moving iron core 28 for sealing with the intake passage A15. A small spring 44 is also arranged between the lower end of the moving iron core 28 and the base 26. Specifically, the air intake channel A15 is provided with a valve port 41 which cooperates with the plug B31. When the coil 25 is energized, a magnetic field is generated near the static iron core 27, and the moving iron core 28 is driven by the electromagnetic force to attract the static iron core 27. At this time, the plug A30 closes the exhaust channel 29, and a gap is generated between the valve port 41 and the plug B31. The air intake channel A15 is opened, and the gas is supplied to the front cavity through the air intake channel A15. When the coil 25 is de-energized, the moving iron core 28 moves downward under the action of gravity and the elastic force of the small spring 44, the exhaust channel 29 is opened, the plug B31 closes the valve port 41, the air intake channel A15 is closed, and the gas is discharged through the exhaust channel 29.

[0038] Preferably, in this embodiment, the interior of the moving iron core 28 is hollow and provided with an accommodating space 32, and a spring 33 is provided in the accommodating space 32. The upper end of the spring 33 abuts against the plug A30, and the lower end of the spring 33 abuts against the plug B31. The spring 33 can effectively play a role in buffering and shock absorption, which is beneficial to prolonging the service life.

[0039] Preferably, in this embodiment, a special-shaped sealing ring is provided between the spacer assembly 3 and the front end cover 42 to improve the sealing performance and prevent gas leakage.

[0040] Preferably, in this embodiment, a Y-shaped sealing ring 40 is sealed between the large piston 5 and the front end cover 42, and the V-shaped opening of the Y-shaped sealing ring 40 faces the spacer assembly 3, ensuring that the large piston 5 maintains good sealing performance during movement.

[0041] The working principle of the utility model is as follows: after the air is taken in through the air inlet 10, it flows through the air inlet channel A15 and the air inlet channel B16 respectively. When the pilot head assembly 2 is not powered on, the air inlet channel A15 is closed, and the gas enters the rear chamber through the air inlet channel B16. At this time, the pressure of the rear chamber is greater than that of the front chamber, pushing the valve stem 4 to move to the first working position. At this time, the air inlet 10 is connected with the first working port 13, and the second working port 14 is connected with the second exhaust port 12. The gas in the chamber B19 quickly enters the chamber C20 through the gas channel 6, thereby improving the response speed of the valve stem 4; when the pilot head assembly 2 is powered on, the air inlet channel A15 is opened. At this time, the gas passes through the air inlet channel A15. It enters the front chamber and also enters the rear chamber through the air inlet passage B16. The force exerted by the gas on the small piston part 17 is the gas pressure multiplied by the cross-sectional area of ​​the small piston part 17. The force exerted by the gas on the large piston 5 is the gas pressure multiplied by the cross-sectional area of ​​the large piston 5. Since the cross-sectional area of ​​the small piston part 17 is smaller than that of the large piston 5, the pressure in the front chamber is greater than that in the rear chamber, pushing the valve stem 4 to move to the second working position. At this time, the air inlet 10 is connected with the second working port 14, and the first working port 13 is connected with the first exhaust port 11. The gas in chamber C20 quickly enters chamber B19 through the gas passage 6, thereby improving the response speed of the valve stem 4.

[0042] The above description is only a preferred embodiment of the present utility model, so all equivalent changes or modifications made according to the structure, features and principles described in the scope of the present utility model patent application are included in the scope of the present utility model patent application.

Claims

1. An explosion-proof valve with a compensating seal structure, comprising a valve body (1), a front end cover (42) being provided at the front end of the valve body (1), a pilot head assembly (2) being provided on the front end cover (42), a valve cavity being provided between the valve body (1) and the front end cover (42), a spacer assembly (3) being fixedly provided in the valve body (1), a valve stem (4) being movably provided in the spacer assembly (3), the valve stem (4) dividing the valve cavity into a front cavity and a rear cavity, a large piston (5) being provided in the front cavity, the front end of the valve stem (4) being against the large piston (5), and characterized in that: The valve stem (4) is hollow inside and is provided with a gas passage (6), which is used to connect the front cavity and the rear cavity. The front end of the spacer assembly (3) is provided with an annular protrusion A (7) and an annular protrusion B (8), and a mounting groove (9) is formed between the annular protrusion A (7) and the annular protrusion B (8). The outer wall of the annular protrusion A (7) is provided with a sealing ring A (34) which is sealed with the valve body (1). The mounting groove (9) is provided with a sealing ring B (35) and a sealing ring C (36), and the sealing ring B (35) is radially sleeved on the outer wall of the sealing ring C (36). The sealing ring B (35) always has a movement tendency to tighten the sealing ring C (36), and the inner wall of the sealing ring C (36) is sealed with the outer wall of the valve stem (4).

2. The explosion-proof valve with a compensating seal structure according to claim 1, characterized in that: The valve body (1) is provided with an air inlet (10), a first exhaust port (11), a second exhaust port (12), a first working port (13) and a second working port (14); an air inlet channel A (15) is formed between the air inlet (10) and the front cavity; an air inlet channel B (16) is formed between the air inlet (10) and the rear cavity; the pilot head assembly (2) is used to control the opening or closing of the air inlet channel A (15); the valve stem (4) moves in the spacer assembly (3) under the action of the air pressure difference between the front cavity and the rear cavity, thereby controlling the switching of the air paths among the air inlet (10), the first exhaust port (11), the second exhaust port (12), the first working port (13) and the second working port (14).

3. The explosion-proof valve with a compensating seal structure according to claim 2, characterized in that: A small piston portion (17) is fixedly provided at the rear end of the valve stem (4); the cross-sectional area of ​​the small piston portion (17) is smaller than the cross-sectional area of ​​the large piston (5); the small piston portion (17) divides the rear chamber into a chamber A (18) and a chamber B (19); the large piston (5) divides the front chamber into a chamber C (20) and a chamber D (21); the air inlet passage A (15) is connected to the chamber D (21); and the air inlet passage B (16) is connected to the chamber A (18).

4. The explosion-proof valve with a compensating seal structure according to claim 3, characterized in that: The rear end of the valve stem (4) is provided with an air hole (22), the air hole (22) being communicated with the gas channel (6) and the chamber B (19) respectively. The front end of the valve stem (4) is provided with a groove portion (23) cooperating with the large piston (5), the groove portion (23) being communicated with the gas channel (6) and the chamber C (20) respectively.

5. The explosion-proof valve with a compensating seal structure according to claim 2, characterized in that: The pilot head assembly (2) comprises a base (26), a sleeve seat (24) and a coil (25); the lower end of the base (26) is fixedly connected to the front end cover (42); the upper end of the base (26) is fixedly connected to the sleeve seat (24); the coil (25) is fixedly arranged on the outer periphery of the sleeve seat (24); a static iron core (27) and a moving iron core (28) are arranged in the sleeve seat (24); the static iron core (27) is fixedly arranged on the sleeve seat (24). The movable iron core (28) is movably arranged below the stationary iron core (27), and an exhaust passage (29) is provided in the hollow interior of the stationary iron core (27). The upper end of the movable iron core (28) is provided with a plug A (30) which is sealed with the exhaust passage (29), and the lower end of the movable iron core (28) is provided with a plug B (31) which is sealed with the intake passage A (15). A small spring (44) is also provided between the lower end of the movable iron core (28) and the base (26).

6. The explosion-proof valve with a compensating seal structure according to claim 5, characterized in that: The movable iron core (28) is hollow inside and provided with an accommodating space (32). A spring (33) is provided in the accommodating space (32). The upper end of the spring (33) abuts against the plug A (30), and the lower end of the spring (33) abuts against the plug B (31).

7. The explosion-proof valve with a compensating seal structure according to claim 1, characterized in that: The sealing ring A (34) is an O-type sealing ring, the sealing ring B (35) is a C-type sealing ring, and the sealing ring C (36) is a T-type sealing ring. The inner wall of the T-type sealing ring is provided with a sealing portion (38) protruding outward along the circumferential direction, and the sealing portion (38) is in sealing cooperation with the outer wall of the valve stem (4).

8. The explosion-proof valve with a compensating seal structure according to claim 7, characterized in that: A plurality of outwardly protruding portions (37) are provided at intervals on the valve stem (4), and the protruding portions (37) are in sealing cooperation with the sealing portion (38).

9. The explosion-proof valve with a compensating seal structure according to claim 1, characterized in that: A special-shaped sealing ring (39) is provided between the spacer assembly (3) and the front end cover (42) for sealing.

10. The explosion-proof valve with a compensating seal structure according to claim 1, characterized in that: A Y-shaped sealing ring (40) is provided between the large piston (5) and the front end cover (42) to seal the large piston (5). The V-shaped opening of the Y-shaped sealing ring (40) faces the spacer assembly (3).

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