Variable orifice electromagnetic pilot valve and method of regulation

Abstract

The application discloses a variable passage electromagnetic pilot valve and a regulating method, and belongs to the electromagnetic pilot valve field. The variable passage electromagnetic pilot valve comprises a valve rod, an electromagnetic valve cover, an upper valve body, an adjusting ring, a piston, a lower valve body, a support frame, an outlet flange, a sleeve set, a positioning bolt and a sealing ring. The position of the positioning bolt is adjusted, so that the passage adjustment of the electromagnetic pilot valve is realized, and meanwhile, the inner and outer diameters of the sleeve and the number of the sleeves are adjusted, so that more passage requirements of the electromagnetic pilot valve are realized, and the operation is convenient and fast. The application can be applied to different main valves in the overpressure protection valve group, the passage requirements of the electromagnetic pilot valve due to the pressure relief speed, and a plurality of electromagnetic pilot valves are integrated on one device, so that the design and machining costs are saved.

Description

Technical Field

[0001] This invention belongs to the field of electromagnetic pilot valves, and specifically relates to a variable diameter electromagnetic pilot valve and its regulating method. Background Technology

[0002] An overpressure protection valve assembly is an overpressure protection device composed of multiple different main valves, most of which are controlled by pilot operation. When the actual operating pressure exceeds the set pressure, the overpressure protection valve assembly needs to open rapidly to ensure the safety of the system and the personal safety of personnel on site. Furthermore, the opening status of the main valves varies depending on the overpressure condition.

[0003] Because valve assemblies consist of main valves of different specifications, their required response times also differ. Therefore, the requirements for the inlet and flow diameters of the pilot valve also vary, as this directly affects the depressurization speed and time of the main valve. In actual engineering projects, selecting the appropriate pilot valve for different main valves often requires a significant amount of work. If the pilot valve of the same nominal diameter is smaller than the theoretical diameter, it will affect the depressurization time of the main valve, thus compromising the safe and stable operation of the system. If it is larger than the theoretical diameter, while still meeting the depressurization speed requirements, the manufacturing cost and processing difficulty of the large-diameter pilot valve will increase.

[0004] Therefore, it is of great significance to study an electromagnetic pilot valve that can be used simultaneously for different main valves in an overpressure protection valve group, and can change its own orifice to change the pressure relief speed of the main valve for different main valves. Summary of the Invention

[0005] The purpose of this invention is to overcome the deficiencies in the prior art and provide an electromagnetic pilot valve for variable diameter applications. This device acts as a pilot valve for different main valves in an overpressure protection valve assembly. It primarily changes the number of sleeves in the main flow area by adjusting the constraint force on different sleeves inside the valve, causing axial displacement of the sleeves under electromagnetic force, thereby changing the flow diameter of the main flow area. Simultaneously, the inlet diameter of the solenoid valve is changed by adding or removing adjustment rings, thus adapting the inlet of the device to different main valves.

[0006] The specific technical solution adopted in this invention is as follows:

[0007] In a first aspect, the present invention provides an electromagnetic pilot valve for variable diameter valves, comprising an upper valve body and a lower valve body sealed and connected by a plurality of horizontally arranged first positioning bolts; the upper valve body is sealed and connected to a solenoid valve cover at its top, has a valve stem inside, and has an inlet on its side wall for connection to a main valve in an overpressure protection valve assembly; the valve stem is sealed and penetrates the solenoid valve cover at its top and is located on the outside, has an electromagnetic limiting member in its middle to prevent the valve stem from sliding out of the upper valve body as a whole, and has a piston fitted and connected at its bottom, allowing the valve stem to slide up and down in the upper valve body together with the piston; the lower valve body has a plurality of coaxially fitted sleeve assemblies inside, the sleeve assemblies... Located below the piston; the innermost sleeve has the same inner diameter as the piston's outer diameter, allowing the piston to seal the sleeve's inner passage; the outermost sleeve's outer wall is sealed against the lower valve body's inner wall; all sleeves are made of ferromagnetic material, and the number of sleeves can be adjusted by horizontally moving the first positioning bolt. Sleeves not limited by the first positioning bolt can be attracted to the upper valve body by the solenoid valve cover, thereby changing the diameter of the fluid passage in the lower valve body; the bottom of the sleeve assembly is connected to the support frame by several horizontally arranged second positioning bolts, and the support frame is fixedly connected to the lower valve body. An outlet flange is sealed at the bottom outlet of the lower valve body.

[0008] Preferably, the inlet has a stepped structure and is fitted with an adjustment ring for adjusting the inlet diameter.

[0009] Preferably, the solenoid valve cover is made of an electromagnet, which generates electromagnetic force when energized; the electromagnetic limiting member is made of ferromagnetic material and can be attracted to the solenoid valve cover together with the sleeve.

[0010] Preferably, the solenoid valve cover, valve stem, piston, and sleeve assembly are all arranged coaxially.

[0011] Preferably, a sealing ring is provided around the piston to seal the innermost sleeve.

[0012] Preferably, the first positioning bolt and the second positioning bolt have the same structure, and the shank includes a threaded section and a cylindrical section that are coaxially connected. The cylindrical section is used to contact the sleeve assembly. One end of the threaded section is connected to the head, and the other end is connected to the cylindrical section. The cross-section of the cylindrical section is smaller than the cross-section of the threaded section.

[0013] Furthermore, the sleeve assembly includes sleeve A, sleeve B, and sleeve C arranged from the inside and outside; sleeve A has an inner diameter of 15mm and an outer diameter of 20mm, sleeve B has an inner diameter of 20mm and an outer diameter of 25mm, and sleeve C has an inner diameter of 25mm and an outer diameter of 32mm; each of sleeve A, sleeve B, and sleeve C has a small hole at its top, into which the cylindrical section of the positioning bolt is inserted to achieve the positioning function of the sleeve.

[0014] Secondly, the present invention provides an adjustment method using any of the variable-diameter electromagnetic pilot valves described in the first aspect, as follows:

[0015] S1: Determine whether the adjusting ring at the inlet needs to be removed based on the diameter of the main valve's pressure relief port. If the diameter of the main valve's pressure relief port is the inner diameter of the adjusting ring, then the adjusting ring does not need to be removed. If the diameter of the main valve's pressure relief port is the outer diameter of the adjusting ring, then the adjusting ring should be removed. In this case, the inlet diameter is the outer diameter of the adjusting ring. Connect the inlet of the variable diameter solenoid pilot valve to the pressure relief port of the main valve.

[0016] S2: In the initial state, the pressure in the main valve has not reached the set pressure, and the variable diameter solenoid pilot valve remains stationary. At this time, the piston is located in the innermost sleeve and achieves a seal. The first positioning bolt has a limiting effect on each sleeve.

[0017] S3: When the pressure inside the main valve reaches the set pressure, pressure is released through the variable-diameter solenoid pilot valve. At this time, the flow port diameter of the variable-diameter solenoid pilot valve is adjusted according to the specifications of the main valve, as follows:

[0018] Rotate the first positioning bolt to move it radially away from the sleeve, thereby releasing the top limit on the inner sleeve; energize the solenoid valve cover, and under the action of electromagnetic attraction, the sleeve with the limit released moves upward and enters the upper valve body, realizing the adjustment of the flow diameter in the lower valve body. At the same time, the valve stem drives the piston to move upward together, opening the variable diameter solenoid pilot valve; when the sleeve with the limit released moves up to the point where it is no longer in contact with the second positioning bolt, rotate the second positioning bolt radially away from the sleeve to avoid obstructing the flow of fluid.

[0019] S4: When the pressure relief process ends, close the variable diameter solenoid pilot valve, so that the pressure inside the main valve gradually increases and eventually closes the main valve by means of the pressure difference; at this time, first rotate the second positioning bolt radially towards the sleeve to reset it so as to support the falling sleeve. At the same time, de-energize the solenoid valve cover, the electromagnetic force disappears, the attracted sleeve resets under the action of gravity, and the valve stem moves downward under the action of gravity, driving the piston to reset, pushing the bottom of the piston back to the inside of the innermost sleeve to achieve a seal.

[0020] Compared with the prior art, the present invention has the following advantages:

[0021] 1) This invention is a key component in an overpressure protection valve assembly. It can be applied to different main valves based on their pressure relief rate requirements for the bore diameter of the electromagnetic pilot valve. It integrates multiple electromagnetic pilot valves into one device, saving design and manufacturing costs.

[0022] 2) The device of the present invention can adjust the flow diameter of the electromagnetic pilot valve by adjusting the position of multiple positioning bolts. At the same time, the inner and outer diameters of the sleeves and the number of sleeves can be adjusted to meet more flow diameter requirements of the electromagnetic pilot valve, which is convenient and quick. Attached Figure Description

[0023] Figure 1 This is a schematic diagram of a variable-bore solenoid pilot valve when it is closed.

[0024] Figure 2 This is a cross-sectional view of a variable-bore electromagnetic pilot valve;

[0025] Figure 3 This is a schematic diagram of the valve stem-piston configuration.

[0026] Figure 4 This is a schematic diagram of the positioning bolts;

[0027] Figure 5 This is a schematic diagram of a variable-bore solenoid pilot valve when it is open;

[0028] Figure 6 This is a partially enlarged schematic diagram of the sleeve assembly;

[0029] In the diagram: 1. Valve stem; 2. Solenoid valve cover; 3. Upper valve body; 4. Adjusting ring; 5. Piston; 6. Lower valve body; 7. Support frame; 8. Outlet flange; 9. Sleeve A; 10. Sleeve B; 11. Sleeve C; 121. First positioning bolt; 122. Second positioning bolt; 13. Sealing ring. Detailed Implementation

[0030] The present invention will be further described and illustrated below with reference to the accompanying drawings and specific embodiments. The technical features of each embodiment of the present invention can be combined accordingly, provided that there is no mutual conflict.

[0031] This invention provides an electromagnetic pilot valve for variable diameter operation, a key component in an overpressure protection valve assembly. The valve's diameter can be adjusted by changing the positions of four positioning bolts. Furthermore, the inner and outer diameters of the sleeves and the number of sleeves can be adjusted to accommodate various diameter requirements. The electromagnetic pilot valve for variable diameter operation mainly includes a valve stem 1, an electromagnetic valve cover 2, an upper valve body 3, a piston 5, a lower valve body 6, a support frame 7, an outlet flange 8, and a sleeve assembly. The right side of the upper valve body 3 is the inlet of the electromagnetic pilot valve, which is connected to the main valve in the overpressure protection valve assembly. High-temperature, high-pressure steam enters the upper valve body 3 through this inlet, flows to the lower valve body 6, and then through the support frame 7 to the outlet flange 8, finally exiting the electromagnetic valve, thus realizing the pressure relief process of the main valve.

[0032] The structural connection methods of each component will be explained in detail below.

[0033] As shown Figure 2 in FIG. 1, the upper valve body 3 and the lower valve body 6 are hermetically connected up and down by a plurality of first positioning bolts 121, and the first positioning bolts 121 are horizontally arranged. An electromagnetic valve cover 2 is connected to the top of the upper valve body 3, and the connection between the two is sealed. A vertical valve stem 1 is provided inside the upper valve body 3, and an inlet is provided on the side wall, and the inlet is used to connect to the pressure relief port of the main valve. As shown Figure 3 in FIG. 2, the top of the valve stem 1 penetrates through the electromagnetic valve cover 2 and is partially located outside, and the contact between the two is sealed; an electromagnetic limiting member is provided in the middle of the valve stem 1, and the electromagnetic limiting member is used to prevent the whole valve stem 1 from sliding out of the upper valve body 3; the bottom of the valve stem 1 is fitted with a piston 5, and the valve stem 1 can slide up and down in the upper valve body 3 together with the piston 5. That is to say, the valve stem 1 is in the shape of "tu", and the electromagnetic limiting member in the shape of a disc above will be attracted by the electromagnetic force after the electromagnetic valve cover (2) is energized, and the disc below is embedded inside the piston 5. When the valve stem 1 moves upward along the axis under the action of the electromagnetic force, it will pull the piston 5 to move upward together.

[0034] In a preferred embodiment of the present invention, the inlet is provided with a stepped structure, and an adjustment ring 4 for adjusting the inlet diameter is embedded inside the inlet. During actual use, the adjustment ring 4 of different specifications can be disassembled or replaced according to the diameter of the pressure relief port to be connected, so as to adapt to the diameter of the pressure relief port and ensure the tight connection between the inlet and the pressure relief port.

[0035] In the present invention, a plurality of coaxially fitted and sleeved sleeve groups are provided inside the lower valve body 6, and the sleeve groups are located below the piston 5. The inner diameter of the sleeve located in the innermost side (i.e., close to the central axis) is the same as the outer diameter of the piston 5, and the inner channel of the sleeve can be closed by the piston 5 in the initial state. The outer wall of the sleeve located in the outermost side is hermetically fitted to the inner wall of the lower valve body 6. Each sleeve is made of ferromagnetic material, and the number of sleeves limited by the first positioning bolt 121 can be adjusted by horizontally moving the first positioning bolt 121. The sleeve not limited by the first positioning bolt 121 on the inner side can be attracted by the electromagnetic valve cover 2 into the upper valve body 3, thereby changing the diameter of the fluid passage in the lower valve body 6.

[0036] In a preferred embodiment of the present invention, the electromagnetic valve cover 2 is made of an electromagnet and generates an electromagnetic force when energized. The electromagnetic limiting member and each sleeve are made of ferromagnetic material and can be attracted to the electromagnetic valve cover 2. In order to achieve a better adjustment effect, the electromagnetic valve cover 2, the valve stem 1, the piston 5 and the sleeve group can be coaxially arranged. In order to ensure that the piston 5 can completely close the fluid flow passage in the initial state, a sealing ring 13 can be wrapped around the piston 5, and the sealing ring 13 can achieve sealing when the piston 5 contacts the inner wall of the innermost sleeve 3.

[0037] In a preferred embodiment of the present invention, two first positioning bolts 121 are symmetrically arranged on the left and right, and their structures are as shown Figure 4As shown: The first positioning bolt 121 includes a head and a shank, wherein the shank includes a threaded section and a cylindrical section coaxially connected. One end of the threaded section is connected to the head, and the other end is connected to the cylindrical section. The cross-section of the cylindrical section is smaller than that of the threaded section. In actual use, the threaded section is used to pass through the upper valve body 3 and / or the lower valve body 6 for fixing, and the cylindrical section is used to contact the sleeve assembly for limiting movement. That is to say, the positioning bolt 12 is stepped. The first step has threads and can be threaded to the upper valve body 3 and the lower valve body 6. The second step is a slender cylinder with high hardness.

[0038] In practical applications, adjacent sleeves need to be fitted together. In a preferred embodiment of the present invention, such as... Figure 6 As shown, the sleeve assembly includes sleeves A9, B10, and C11, arranged from the inside out. Sleeve A9 has an inner diameter of 15mm and an outer diameter of 20mm, sleeve B10 has an inner diameter of 20mm and an outer diameter of 25mm, and sleeve C11 has an inner diameter of 25mm and an outer diameter of 32mm. Each of sleeves A9, B10, and C11 has a small hole at its top, into which the cylindrical section of the positioning bolt 12 is inserted to position the sleeve.

[0039] In this invention, the bottom of the sleeve assembly is connected to the support frame 7 by a plurality of horizontally arranged second positioning bolts 122, the support frame 7 is fixedly connected to the lower valve body 6, and the lower valve body 6 has an outlet flange 8 sealed at the bottom outlet.

[0040] In a preferred embodiment of the present invention, two second positioning bolts 122 are symmetrically arranged on the left and right sides, and their structure is as follows: Figure 4 As shown: The second positioning bolt 122 includes a head and a shank, wherein the shank includes a threaded section and a cylindrical section coaxially connected. One end of the threaded section is connected to the head, and the other end is connected to the cylindrical section. The cross-section of the cylindrical section is smaller than that of the threaded section. In actual use, the threaded section is used to pass through the lower valve body 6 for fixing, and the cylindrical section is used to contact the sleeve assembly for support.

[0041] The present invention also provides an adjustment method using the above-mentioned variable diameter electromagnetic pilot valve, the method being as follows:

[0042] S1: Determine whether the adjusting ring 4 at the inlet needs to be removed based on the diameter of the main valve's pressure relief port. If the diameter of the main valve's pressure relief port is the inner diameter of the adjusting ring 4, then the adjusting ring 4 does not need to be removed. If the diameter of the main valve's pressure relief port is the outer diameter of the adjusting ring 5, then the adjusting ring 4 should be removed, and the inlet diameter will then be the outer diameter of the adjusting ring 4. Connect the inlet of the variable diameter solenoid pilot valve to the pressure relief port of the main valve.

[0043] S2: In the initial state, the pressure in the main valve has not reached the set pressure, and the variable diameter solenoid pilot valve remains stationary. At this time, the piston 5 is located in the innermost sleeve and achieves a seal. The first positioning bolt 121 has a limiting effect on each sleeve.

[0044] S3: When the pressure inside the main valve reaches the set pressure, pressure is released through the variable-diameter solenoid pilot valve. At this time, first adjust the flow port diameter of the variable-diameter solenoid pilot valve according to the specifications of the main valve, as follows:

[0045] Rotate the first positioning bolt 121 to move it radially away from the sleeve, thereby releasing the top limit on the inner sleeve. Energize the solenoid valve cover 2; under the action of electromagnetic attraction, the released sleeve moves upward and enters the upper valve body 3, adjusting the flow diameter in the lower valve body 6. Simultaneously, the valve stem 1 drives the piston 5 upward, opening the variable-diameter solenoid pilot valve. Once the released sleeve has moved upward and is no longer in contact with the second positioning bolt 122, rotate the second positioning bolt 122 radially away from the sleeve to avoid obstructing fluid flow.

[0046] S4: When the pressure relief process ends, close the variable diameter solenoid pilot valve, causing the pressure inside the main valve to gradually increase and eventually close the main valve due to the pressure difference. At this time, first rotate the second positioning bolt 122 radially towards the sleeve to reset it so as to support the falling sleeve. At the same time, de-energize the solenoid valve cover 2, the electromagnetic force disappears, and the attracted sleeve resets under the action of gravity. Meanwhile, the valve stem 1 moves downward under the action of gravity, driving the piston 5 to reset and pushing the bottom end of the piston 5 back into the innermost sleeve to achieve a seal.

[0047] In this embodiment, taking a sleeve assembly having three sleeves—sleeve A9, sleeve B10, and sleeve C11—arranged from the inside out, the adjustment method is specifically described as follows:

[0048] S1: As Figure 1 As shown, in the initial state, the pressure inside the main valve has not reached the set pressure, and the device remains stationary. At this time, the bottom end of the piston 5 passes over sleeves A9, B10 and C11, and the sealing ring 13 contacts the inside of sleeve A9, achieving a seal. At this time, the outer side of the second-stage cylindrical step of the first positioning bolt 121 is flush with the inner diameter of sleeve A9. That is, at this time, the first positioning bolt 121 plays a limiting role for sleeves A9, B10 and C11. The flow port diameter at this time is the inner diameter of sleeve A9.

[0049] S2: As the pressure inside the main valve increases, when the pressure inside the main valve reaches the set pressure, it is necessary to release the pressure through the solenoid pilot valve. At this time, it depends on the diameter of the pressure relief port of the main valve to determine whether the adjusting ring 4 needs to be removed. If the diameter of the pressure relief port of the main valve is the inner diameter of the adjusting ring, then the adjusting ring 4 does not need to be removed. If the diameter of the pressure relief port of the main valve is the outer diameter of the adjusting ring 5, then the adjusting ring 4 is removed. At this time, the inlet diameter is the outer diameter of the adjusting ring. It is connected to the main valve by bolts, and the pressure relief port of the main valve coincides with the inlet of the solenoid pilot valve, ready to release pressure.

[0050] S3: When the main valve needs to be opened, adjust the flow diameter of the solenoid pilot valve according to the main valve specifications. At this time, the two upper first positioning bolts 121 limit the sleeves A9, B10, and C11. By rotating the first positioning bolts, they move radially away from the center. When the outermost ends of the two upper first positioning bolts 121 are far away from the outer diameter of sleeve A9, they no longer limit sleeve A9. The two lower second positioning bolts 122 mainly support sleeves A9, B10, and C11. When the first positioning bolt 121 no longer limits the movement of sleeve A, the solenoid valve cover 2 is energized. The electromagnetic force attracts sleeve A to move axially upwards, eventually connecting it to the solenoid valve cover 2. Simultaneously, the valve stem 1, under the electromagnetic force, drives the piston 5 upwards, opening the solenoid pilot valve. When sleeve A9 is no longer in contact with the two second positioning bolts 122, rotating the second positioning bolts 122 makes the outermost layer contact the inner diameter of sleeve B10. This completes the conversion of the flow orifice diameter of the solenoid pilot valve. Figure 5 As shown, this is suitable for main valves that require a high pressure relief rate;

[0051] S4: When the pressure relief process ends, the solenoid pilot valve needs to be closed, causing the pressure inside the main valve to rise and eventually close the main valve due to the pressure difference. At this time, the two second positioning bolts 122 below need to be rotated inward so that their inner sides are tangent to the inner diameter of the sleeve A9. This provides support for the sleeve A9 when it resets. At the same time, the solenoid valve cover 2 is de-energized, and the electromagnetic force disappears. The sleeve A9 resets under the action of gravity, and the valve stem 1 moves downward under the action of gravity, pushing the piston 5 downward. The bottom of the piston 5 is pushed again past the top of the sleeve A9, and the sealing ring 13 contacts the sleeve A9, achieving a seal again.

[0052] S5: When the main valve has a greater requirement for the flow diameter of the electromagnetic pilot valve, the number of sleeves constrained by the first positioning bolt 121 is adjusted, and the above steps S1 to S4 are repeated to realize the effect of electromagnetic force on multiple sleeves, and finally change the flow diameter of the electromagnetic pilot valve.

[0053] The embodiments described above are merely preferred embodiments of the present invention and are not intended to limit the invention. Those skilled in the art can make various changes and modifications without departing from the spirit and scope of the invention. Therefore, all technical solutions obtained through equivalent substitution or transformation fall within the protection scope of the present invention.

Claims

1. A variable-diameter electromagnetic pilot valve, characterized in that, The system includes an upper valve body (3) and a lower valve body (6) sealed together by several horizontally arranged first positioning bolts (121); the upper valve body (3) is sealed with a solenoid valve cover (2) at the top, and has a valve stem (1) inside, with an inlet on the side wall for connecting to the main valve; the valve stem (1) is sealed through the solenoid valve cover (2) at the top and located on the outside, and has an electromagnetic limiting component in the middle to prevent the valve stem (1) from sliding out of the upper valve body (3) as a whole, and has a piston (5) fitted at the bottom, so that the valve stem (1) can slide up and down in the upper valve body (3) together with the piston (5); the lower valve body (6) has several coaxially fitted sleeve groups inside, and the sleeve groups are located below the piston (5); the sleeve groups include several sleeves arranged from the inside to the outside. The inner diameter of the innermost sleeve is the same as the outer diameter of the piston (5), and the piston (5) can seal the inner channel of the sleeve; the outer wall of the outermost sleeve is sealed and fitted to the inner wall of the lower valve body (6); each sleeve is made of ferromagnetic material, and the number of sleeves can be adjusted by horizontally moving the first positioning bolt (121). The sleeves that are not limited by the first positioning bolt (121) can be attracted to the upper valve body (3) by the solenoid valve cover (2), thereby changing the size of the fluid channel in the lower valve body (6); the bottom of the sleeve group is connected to the support frame (7) by several horizontally arranged second positioning bolts (122), the support frame (7) is fixedly connected to the lower valve body (6), and the outlet flange (8) is sealed at the bottom outlet of the lower valve body (6).

2. The variable-diameter electromagnetic pilot valve according to claim 1, characterized in that, The inlet has a stepped structure and is fitted with an adjustment ring (4) for adjusting the inlet diameter.

3. The variable diameter electromagnetic pilot valve according to claim 1, characterized in that, The solenoid valve cover (2) is made of electromagnet and generates electromagnetic force when energized; the electromagnetic limiting component is made of ferromagnetic material and can be attracted to the solenoid valve cover (2) together with the sleeve.

4. The variable-diameter electromagnetic pilot valve according to claim 1, characterized in that, The solenoid valve cover (2), valve stem (1), piston (5) and sleeve assembly are all arranged coaxially.

5. The variable diameter electromagnetic pilot valve according to claim 1, characterized in that, The piston (5) is surrounded by a sealing ring (13) for sealing the innermost sleeve.

6. The variable diameter electromagnetic pilot valve according to claim 1, characterized in that, The first positioning bolt (121) and the second positioning bolt (122) have the same structure. The rod includes a threaded section and a cylindrical section that are coaxially connected. The cylindrical section is used to contact the sleeve assembly. One end of the threaded section is connected to the head, and the other end is connected to the cylindrical section. The cross-section of the cylindrical section is smaller than the cross-section of the threaded section.

7. A variable-diameter electromagnetic pilot valve according to claim 6, characterized in that, The sleeve assembly includes sleeve A (9), sleeve B (10) and sleeve C (11) arranged from the inside to the outside; sleeve A (9) has an inner diameter of 15 mm and an outer diameter of 20 mm, sleeve B (10) has an inner diameter of 20 mm and an outer diameter of 25 mm, and sleeve C (11) has an inner diameter of 25 mm and an outer diameter of 32 mm; sleeve A (9), sleeve B (10) and sleeve C (11) all have small holes at the top, which are used for inserting the cylindrical section of the positioning bolt (12) into the small holes to achieve the positioning function of the sleeve.

8. A method for adjusting the variable-diameter electromagnetic pilot valve as described in claim 2, characterized in that, Specifically as follows: S1: Determine whether the adjusting ring (4) at the inlet needs to be removed based on the diameter of the main valve's pressure relief port. If the diameter of the main valve's pressure relief port is the inner diameter of the adjusting ring (4), then the adjusting ring (4) does not need to be removed. If the diameter of the main valve's pressure relief port is the outer diameter of the adjusting ring (4), then the adjusting ring (4) should be removed. At this time, the inlet diameter is the outer diameter of the adjusting ring (4). Connect the inlet of the variable diameter solenoid pilot valve to the pressure relief port of the main valve. S2: In the initial state, the pressure in the main valve has not reached the set pressure, and the variable diameter electromagnetic pilot valve remains stationary. At this time, the piston (5) is located in the innermost sleeve and achieves sealing. The first positioning bolt (121) has a limiting effect on each sleeve. S3: When the pressure inside the main valve reaches the set pressure, pressure is released through the variable-diameter solenoid pilot valve. At this time, the flow port diameter of the variable-diameter solenoid pilot valve is adjusted according to the specifications of the main valve, as follows: Rotate the first positioning bolt (121) to move it radially away from the sleeve to release the top limit of the inner sleeve; energize the solenoid valve cover (2), and under the action of electromagnetic attraction, the sleeve that has been released from the limit moves upward and enters the upper valve body (3) to adjust the flow diameter in the lower valve body (6). At the same time, the valve stem (1) drives the piston (5) to move upward together, so that the variable diameter solenoid pilot valve opens; when the sleeve that has been released from the limit moves up to the point where it is no longer in contact with the second positioning bolt (122), rotate the second positioning bolt (122) radially away from the sleeve to avoid obstructing the flow of fluid. S4: When the pressure relief process ends, close the variable diameter solenoid pilot valve, so that the pressure inside the main valve gradually increases and finally the main valve is closed by relying on the pressure difference. At this time, first rotate the second positioning bolt (122) radially towards the sleeve to reset it so as to support the falling sleeve. At the same time, de-energize the solenoid valve cover (2), the electromagnetic force disappears, the attracted sleeve is reset under the action of gravity, and the valve stem (1) moves downward under the action of gravity, driving the piston (5) to reset, pushing the bottom end of the piston (5) to the inside of the innermost sleeve again to achieve sealing.

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