A pilot-operated combined safety valve core structure and its application method

Abstract

This invention discloses a combined safety valve core structure with pilot function and its usage method, relating to the field of safety valve technology. The main valve core is slidably and sealed to the inner wall of the valve body, while a secondary valve core is slidably and sealed to the central through-hole. A lower spring is sleeved around the secondary valve core. A main valve core seat is located at the bottom of the valve body. A pressure chamber is formed between the upper end face of the main valve core and the top of the inner wall of the valve body. The bottom medium inlet of the valve body is connected to the pressure chamber via a branch pipe. An upper spring is located within the pressure chamber, and a secondary valve core seat is located at the connection between the branch pipe and the top of the valve body. This invention achieves a synergistic effect of "secondary valve core pilot triggering and main valve core rapid response" through the coaxial nesting design of the main and secondary valve cores, combined with a dynamic balance mechanism between the upper and lower spring forces and the medium pressure. This invention possesses the rapid response characteristics of a direct-start safety valve, while also having the advantages of a pilot-operated safety valve, such as good sealing performance, pilot characteristics, and minimal impact from back pressure.

Description

Technical Field

[0001] This invention relates to the field of safety valve technology, specifically to a fast-response combined safety valve core structure with pilot function and its usage method, particularly for valves in nuclear power plants and other applications with high safety valve performance requirements. Background Technology

[0002] As a core protective device in industrial pipeline systems, the performance of safety valves directly affects production safety. In fields such as nuclear power and petrochemicals, fluid systems often face extreme conditions involving high temperatures, high pressures, and corrosive media, placing stringent demands on the sealing performance and response speed of safety valves. Traditional safety valves are mainly divided into two categories:

[0003] Pilot-operated safety valve: The main valve is controlled by a pilot valve. It has excellent sealing performance, but it has a complex structure, slow response speed, and is easily affected by back pressure.

[0004] Direct-start safety valve: It relies on the pressure of the medium to directly drive the valve core, which has a fast response but poor sealing performance and is prone to leakage or abnormal opening due to wear.

[0005] Especially in nuclear power settings, even minor leaks of steam can trigger a chain of safety hazards, and existing safety valves struggle to balance rapid action with long-term sealing. For example, traditional pilot-operated valves require a separate pilot valve to work with the main valve, resulting in complex piping layouts and high maintenance costs; while direct-start valves are prone to failure after frequent opening and closing due to wear on the sealing surface.

[0006] Therefore, there is an urgent need for an integrated design that can improve sealing reliability through a pilot mechanism and optimize the structure to shorten response time. Summary of the Invention

[0007] The purpose of this invention is to overcome the shortcomings of existing technologies and provide a combined safety valve core structure with pilot-operated function and its usage method. This invention possesses the rapid response characteristics of a direct-acting safety valve, while also having the advantages of a pilot-operated safety valve, such as good sealing performance, pilot characteristics, and less susceptibility to back pressure. This invention modifies the non-uniform area main valve core of a classic pilot-operated safety valve by adding a small non-uniform area secondary valve core inside the main valve core. The pilot function is achieved through the advance action of the secondary valve core, resulting in a faster response speed than a pilot-operated safety valve and better sealing performance than a direct-acting safety valve.

[0008] The specific technical solution adopted in this invention is as follows:

[0009] In a first aspect, the present invention provides a combined safety valve core structure with pilot function, including a main valve core and a secondary valve core coaxially mounted inside the valve body;

[0010] The main valve core is slidably and sealed to the inner wall of the valve body. A stepped through-hole is axially opened in the middle, and a secondary valve core is slidably and sealed to the through-hole. The through-hole includes three sections from top to bottom. The first section is used to limit the lower limit position of the secondary valve core within the main valve core. The second section has a gap with the secondary valve core and communicates with the medium outlet through a vent hole opened on the main valve core. A lower spring is sleeved on the outside of the secondary valve core located in the third section. A medium outlet is opened on one side of the valve body, and a main valve core seat is provided at the bottom. When the main valve core is at the lower limit position, it can connect with the main valve core. The valve core and seat cooperate to achieve a seal, and a pressure chamber is formed between the upper end face of the main valve core and the top of the inner wall of the valve body. The medium inlet at the bottom of the valve body is connected to the pressure chamber through a branch pipe. An upper spring is provided in the pressure chamber, and the two ends of the upper spring are in contact with the top of the inner wall of the valve body and the upper end face of the main valve core, respectively. A secondary valve core seat is provided at the connection between the branch pipe and the top of the valve body. When the secondary valve core is in the upper limit position, it can cooperate with the secondary valve core seat to achieve a seal. The upper end face area of ​​the main valve core is larger than its lower end face area, and the upper end face area of ​​the secondary valve core is smaller than its lower end face area.

[0011] Preferably, the upper part of the main valve core is provided with a third sealing ring along the circumferential direction to achieve a seal with the inner wall of the valve body.

[0012] Preferably, the outer periphery of the auxiliary valve core located at the first and third sections of the through hole is provided with a second sealing ring and a first sealing ring, respectively, to achieve a sealed connection with the main valve core.

[0013] Preferably, the effective distance that the lower spring can compress during use is greater than the distance from the upper surface of the secondary valve core to the secondary valve core seat.

[0014] Preferably, the lower end face of the main valve core and the top face of the main valve core seat are both set as conical surfaces that can cooperate with each other to increase the sealing performance.

[0015] Preferably, the upper end face of the secondary valve core and the bottom face of the secondary valve core seat are both set as conical surfaces that can cooperate with each other to increase the sealing performance.

[0016] Preferably, the lower part of the secondary valve core has a T-shaped structure, and the lower spring is limited by the inner wall of the connection between the bottom of the secondary valve core and the second and third sections of the main valve core through hole.

[0017] Preferably, the main valve core, auxiliary valve core, lower spring, upper spring, main valve core seat, auxiliary valve core seat, and valve body are all coaxially arranged.

[0018] Preferably, both the upper and lower springs are always in a compressed state.

[0019] Secondly, the present invention provides a method of using the combined safety valve core structure with pilot function as described in any one of the first aspects, as follows:

[0020] S1: When the medium pressure at the medium inlet is the normal pressure, the main valve core is in the lower limit position, the auxiliary valve core is in the lower limit position inside the main valve core, and the combined safety valve core structure is in the closed state; the medium enters through the medium inlet and fills the pipeline, and at the same time, the medium fills the pressure chamber through the branch section;

[0021] Because the upper surface area of ​​the main valve core is larger than its lower surface area, a downward medium force is generated under the pressure of the same medium. At the same time, the upper spring is in a compressed state and exerts a downward spring force on the upper surface of the main valve core, so that the lower surface of the main valve core is tightly pressed against the main valve core seat, ensuring the sealing performance of the entire circuit. The lower spring is in a compressed state at this time and exerts a downward force on the auxiliary valve core. Although the lower surface area of ​​the auxiliary valve core is larger than the upper surface area, resulting in an upward medium force on the auxiliary valve core under the action of the medium, in this state, the upward medium force of the medium on the auxiliary valve core is less than the downward spring force of the lower spring, so that the auxiliary valve core can make tight contact with the main valve core under the total downward force, achieving a seal. At this time, although the lower spring exerts an upward spring force on the main valve core, this spring force is less than the medium force caused by the difference in the upper and lower surface areas of the main valve core, thus preventing the main valve core from moving upward.

[0022] S2: When the medium pressure at the medium inlet gradually increases, both the main valve core and the auxiliary valve core gradually move upward, and the valve core structure of the combined safety valve is in the upward opening state;

[0023] At the beginning of this stage, the main valve core is still subjected to downward medium force, thus sealing with the main valve core seat. At this time, because the lower end face area of ​​the auxiliary valve core is larger than the upper end face area, and the medium pressure is also higher, the upward medium force on the auxiliary valve core in this state is greater than the downward spring force of the lower spring, causing the auxiliary valve core to move upward and the lower spring to be further compressed. When the auxiliary valve core moves upward to the auxiliary valve core seat, it is limited and stops moving, and makes tight contact with the auxiliary valve core seat to achieve a seal, cutting off the connection between the branch section and the pressure chamber. The movement allows the medium in the pressure chamber to flow into the main valve core through the vent hole and out of the valve body through the medium outlet. After the medium in the pressure chamber is released, the pressure inside the pressure chamber decreases. At this time, the upward medium pressure on the lower end face of the main valve core is greater than the sum of the downward medium pressure and the spring force on the upper end face, causing the main valve core to gradually move upward under the action of the upward medium force and open. After the main valve core moves upward, the medium at the medium inlet is released in large quantities directly from the medium outlet through the main valve core seat, reducing the pressure of the entire pipeline and thus achieving overpressure protection.

[0024] S3: When the medium pressure at the medium inlet rises to the set pressure, both the main valve core and the auxiliary valve core are at their upper limit positions, and the valve core structure of the combined safety valve is in a fully open state.

[0025] The auxiliary valve core remains in close contact with the auxiliary valve core seat. At the same time, the upper spring is in a compressed state. The upward medium force and the downward spring force on the main valve core are balanced, and a stable medium discharge outlet is formed between the lower end face and the main valve core seat. The medium at the medium inlet is continuously discharged through the medium outlet, causing the pressure in the entire pipeline to gradually decrease.

[0026] S4: When the medium pressure at the medium inlet gradually decreases from the set pressure to the normal pressure, the main valve core and the auxiliary valve core move downwards simultaneously until the initial state, and the valve core structure of the combined safety valve gradually returns to the closed state.

[0027] As the medium pressure at the medium inlet decreases, the upward medium force acting on the auxiliary valve core gradually decreases until it is less than the downward force exerted by the lower spring on the auxiliary valve core. At this point, the auxiliary valve core moves back to the lower limit position within the main valve core. At this time, the branch pipe is connected to the pressure chamber, but most of the medium is still discharged directly from the medium outlet through the main valve core seat. As some medium enters the branch pipe, and the pressure in the entire pipeline continuously decreases due to the venting, the upward medium force acting on the main valve core gradually decreases until it is less than the downward spring force of the upper spring. The main valve core gradually moves downward, causing the venting channel formed between the main valve core and the main valve core seat to gradually narrow. Simultaneously, the medium enters the pressure chamber through the branch pipe, and the downward medium force on the upper end face of the main valve core gradually increases. Under the action of the downward spring force of the upper spring, the main valve core, together with the auxiliary valve core, moves downward synchronously until it is completely closed and returns to the initial state of S1.

[0028] Compared with the prior art, the present invention has the following advantages:

[0029] 1) Compared with traditional pilot-operated safety valves, the response speed is greatly improved and the reliability of the safety valve operation is enhanced, thereby improving the safety of the circuit.

[0030] 2) The structure has low manufacturing cost and is simple and convenient to implement. Compared with the traditional pilot-operated safety valve structure, it is simpler and easier to process and manufacture.

[0031] 3) The structure is simple and compact, integrating the functions of a pilot valve and a safety valve with a single main valve, which can optimize pipeline layout design.

[0032] 4) Improved sealing performance: Compared with traditional direct-lift safety valves, the sealing performance is greatly improved, and the use of a secondary valve core to drive the main valve core also provides greater stability.

[0033] 5) Wide range of applications: It integrates the advantages of traditional direct-start safety valves and pilot-operated safety valves, has strong integrated advantages, fewer application restrictions, and is suitable not only for ordinary chemical plants, but also for extreme working conditions such as nuclear power plants. Attached Figure Description

[0034] Figure 1This is a schematic diagram of the overall structure of the device of the present invention;

[0035] Reference numerals in the attached drawings: 1. Main valve core; 2. Auxiliary valve core; 3. Lower spring; 4. Medium inlet; 5. Branch pipe; 6. Medium outlet; 7. Vent hole; 8. Main valve core seat; 9. Auxiliary valve core seat; 10. Pressure chamber; 11-a first sealing ring; 11-b second sealing ring; 11-c third sealing ring; 12. Valve body; 13. Upper spring. Detailed Implementation

[0036] 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.

[0037] This invention utilizes a coaxial nested design of the main valve core and the auxiliary valve core, combined with a dynamic balance mechanism between the upper and lower spring forces and the medium pressure, to achieve a synergistic effect of "auxiliary valve core pilot triggering and main valve core rapid response." This structure simplifies the traditional multi-stage valve body design, reduces manufacturing costs, and significantly improves sealing performance and operational stability through optimization of the conical sealing surface and vent hole. It is suitable for fields such as nuclear power where safety and response speed are extremely critical.

[0038] like Figure 1 The diagram shows a schematic of a combined safety valve core structure with pilot function provided by the present invention. This combined safety valve core structure mainly includes a main valve core 1 and a secondary valve core 2, which are coaxially mounted inside the valve body 12. The present invention proposes a novel combined structure that can improve response speed and sealing performance: In the closed state, the main valve core is pressed tightly against the valve seat due to the area difference and medium pressure, while the secondary valve core remains sealed under the action of spring force; when the pressure reaches the set value, the secondary valve core opens first, releasing the medium in the pressure chamber through the vent hole, triggering the main valve core to open rapidly, thus achieving overpressure protection.

[0039] The structure and connection method of each component in the device of the present invention will be described in detail below.

[0040] In the device of the present invention, the main valve core 1 is disposed in the inner cavity of the valve body 12, and the outer wall of the main valve core 1 is sealed to the inner wall of the valve body 12, and the main valve core 1 can slide up and down along the inner wall of the valve body 12. A stepped through hole is axially opened in the middle of the main valve core 1, and a secondary valve core 2 is disposed in the through hole. The secondary valve core 2 can slide up and down in the through hole, and maintains a sealed state with the inner wall of the through hole during the sliding process.

[0041] In a preferred embodiment of the present invention, in order to achieve a sealed sliding connection between the main valve core 1 and the valve body 12, a third sealing ring 11-c can be provided circumferentially on the upper part of the main valve core 1, and the sealing is achieved between the third sealing ring 11-c and the inner wall of the valve body 12.

[0042] In the device of this invention, the through hole has a three-section structure from top to bottom, and the cross-sectional diameter of the middle section (i.e., the second section) is smaller than that of the first and third sections. The top of the auxiliary valve core 2 has a protrusion with a larger cross-sectional diameter, which cooperates with the first section of the through hole to achieve a seal in the initial state; and since the cross-section of the first section of the through hole is larger than that of the second section, the through hole in this section can limit the lower limit position of the auxiliary valve core 2 in the main valve core 1, that is, it can prevent the protrusion on the top of the auxiliary valve core 2 from entering the second section of the through hole. There is a certain gap between the second section of the through hole and the main body of the auxiliary valve core 2, and a vent hole 7 is provided on one side of the main valve core 1 located at the second section, which is connected to the medium outlet 6. The medium outlet 6 is located on one side of the valve body 12. A lower spring 3 is coaxially sleeved on the outside of the auxiliary valve core 2 located in the third section, and the lower spring 3 can provide a vertical spring force on the auxiliary valve core 2.

[0043] In a preferred embodiment of the present invention, the through hole is vertically oriented and the vent hole 7 is horizontally opened on one side of the main valve core 1.

[0044] In a preferred embodiment of the present invention, to fix the lower spring 3 and achieve sealed sliding, the cross-section of the lower end face of the auxiliary valve core 2 can be enlarged, i.e., the lower end face and the main body of the auxiliary valve core 2 form an inverted T-shape. This allows both ends of the lower spring 3 to contact the lower end face of the auxiliary valve core 2 and the inner wall of the main valve core 1 located at the connection between the second and third sections of the through hole, thereby fixing the lower spring 3. Simultaneously, to achieve a sealed sliding connection between the auxiliary valve core 2 and the main valve core 1, a second sealing ring 11-b can be circumferentially provided on the protruding top of the auxiliary valve core 2, and a first sealing ring 11-a can be circumferentially provided on the lower end face of the auxiliary valve core 2. The sealed sliding connection with the main valve core 1 is achieved through the second sealing ring 11-b and the first sealing ring 11-a.

[0045] In a preferred embodiment of the present invention, the effective distance that the lower spring 3 can be compressed during use is greater than the distance from the upper surface of the secondary valve core 2 to the secondary valve core seat 9, so that the secondary valve core can contact the upper secondary valve core seat.

[0046] In the device of this invention, a main valve core seat 8 is provided at the bottom of the valve body 12. When the main valve core 1 is in the lower limit position, the main valve core 1 can cooperate with the main valve core seat 8 to achieve a seal. The upper end face of the main valve core 1 and the top of the inner wall of the valve body 12 form a pressure chamber 10. The bottom medium inlet 4 of the valve body 12 is connected to the pressure chamber 10 through a branch pipe 5. In actual use, in the initial state, the medium entering from the medium inlet 4 can contact the lower end faces of the main valve core 1 and the auxiliary valve core 2, generating an upward force on them, and can also enter the pressure chamber 10 through the branch pipe 5. In actual use, the pressure of the medium entering the internal chamber of the pressure chamber 10 mainly acts on the upper end face of the main valve core 1.

[0047] In a preferred embodiment of the present invention, the lower end face of the main valve core 1 and the top face of the main valve core seat 8 are both set as conical surfaces. The sealing performance between the main valve core 1 and the main valve core seat 8 can be increased by the cooperation of the two conical surfaces.

[0048] In the device of this invention, an upper spring 13 is provided inside the pressure chamber 10, which provides a vertical spring force to the main valve core 1. The upper and lower ends of the upper spring 13 contact the top of the inner wall of the valve body 12 and the upper end face of the main valve core 1, respectively, thereby fixing its position. A secondary valve core seat 9 is provided at the connection between the branch pipe 5 and the top of the valve body 12, and the secondary valve core seat 9 is located inside the top of the valve body 12. When the secondary valve core 2 is in the upper limit position, it can cooperate with the secondary valve core seat 9 to achieve a seal. In order to achieve the synergistic effect of "secondary valve core pilot triggering and main valve core rapid response", the upper end face area of ​​the main valve core 1 is set to be larger than its lower end face area, and the upper end face area of ​​the secondary valve core 2 is set to be smaller than its lower end face area.

[0049] In a preferred embodiment of the present invention, the upper end face of the secondary valve core 2 and the bottom face of the secondary valve core seat 9 are both set as conical surfaces. The sealing performance of the secondary valve core 2 and the secondary valve core seat 9 can be increased by the mutual cooperation of the two conical surfaces.

[0050] In a preferred embodiment of the present invention, the main valve core 1, the auxiliary valve core 2, the lower spring 3, the upper spring 13, the main valve core seat 8, the auxiliary valve core seat 9, and the valve body 12 are all coaxially arranged.

[0051] In a preferred embodiment of the present invention, in order to enhance the sealing effect, both the upper spring 13 and the lower spring 3 are always in a compressed state.

[0052] Based on the above-mentioned combined safety valve core structure with pilot function, the present invention also provides a method of use with pilot function that can improve response speed and sealing performance, as follows:

[0053] S1: When the medium pressure at medium inlet 4 is at normal pressure (i.e., the circuit pressure is at normal pressure), the main valve core 1 is at its lower limit position, and the auxiliary valve core 2 is at its lower limit position within the main valve core 1. The entire structure of the combined safety valve core is in a closed state. The medium enters through medium inlet 4 and fills the pipeline. At the same time, the medium fills the pressure chamber 10 through branch section 5.

[0054] Since the upper end face area of ​​the main valve core 1 is larger than its lower end face area, the upper and lower end faces form an area difference. Under the pressure of the same medium, a downward medium force is formed. At the same time, the upper spring 13 is in a compressed state and gives the upper end face of the main valve core 1 a downward spring force. Therefore, the lower end face of the main valve core 1 is tightly pressed onto the main valve core seat 8, ensuring good sealing performance of the entire circuit.

[0055] At this time, the lower spring 3 is in a compressed state, exerting a downward force on the secondary valve core 2. Although the lower end face area of ​​the secondary valve core 2 is larger than its upper end face area, resulting in an upward medium force on the secondary valve core 2 under the action of the medium, in the current state, the upward medium force on the secondary valve core 2 is less than the downward spring force exerted by the lower spring 3 on it. Therefore, under the total downward force, the secondary valve core 2 can make tight contact with the main valve core 1 and is located at the lower limit position within the main valve core 1, thereby achieving a sealing effect. At this time, although the lower spring 3 exerts an upward spring force on the main valve core 1, this spring force is less than the downward medium force on the main valve core 1 due to the difference in the upper and lower end face areas, thus preventing the main valve core 1 from moving upward.

[0056] S2: When the medium pressure at medium inlet 4 gradually increases (i.e., the circuit pressure gradually increases), both the main valve core 1 and the auxiliary valve core 2 gradually move upward, and the valve core structure of the combined safety valve is in the upward opening state.

[0057] In the initial short period of this stage, the main valve core 1 is still subjected to a downward medium force, thus sealing with the main valve core seat 8. At this time, because the lower end face area of ​​the auxiliary valve core 2 is larger than its upper end face area, and the medium pressure is also higher, the upward medium force on the auxiliary valve core 2 in this state is greater than the downward spring force exerted on it by the lower spring 3, causing the auxiliary valve core 2 to move upward, and the lower spring 3 is further compressed. When the auxiliary valve core 2 moves upward to the auxiliary valve core seat 9, it is limited and stops moving, and makes tight contact with the auxiliary valve core seat 9 to achieve a seal, while also cutting off the connection between the branch section 5 and the pressure chamber 10. As the auxiliary valve core 2 moves upward, the medium in the pressure chamber 10 flows into the through hole of the main valve core 1, and is discharged from the valve body 12 through the vent hole 7 and the medium outlet 6, thus achieving venting.

[0058] After the medium in pressure chamber 10 is released, the internal pressure of pressure chamber 10 decreases. At this time, the upward medium pressure on the lower end face of the main valve core 1 is much greater than the downward force on the upper end face (the downward force is the sum of the medium pressure and the spring force). As a result, the main valve core 1 gradually moves upward under the action of the upward medium force, thus opening the main valve core 1. After the main valve core 1 moves upward, the medium at the medium inlet 4 is released in large quantities directly from the medium outlet 6 through the main valve core seat 8, reducing the pressure of the entire pipeline, thereby enabling the safety valve to achieve overpressure protection.

[0059] S3: When the medium pressure at medium inlet 4 rises to the set pressure (i.e., the circuit pressure is at the set pressure), both the main valve core 1 and the auxiliary valve core 2 are at the upper limit position, and the valve core structure of the combined safety valve is in the fully open state.

[0060] The auxiliary valve core 2 remains in close contact with the auxiliary valve core seat 9, while the upper spring 13 is compressed. The upward medium force on the main valve core 1 is balanced by the downward spring force exerted by the upper spring 13, and the main valve core 1 is in its upper limit position. A stable medium discharge outlet is formed between the lower end face of the main valve core 1 and the main valve core seat 8. At this time, the medium at the medium inlet 4 is continuously discharged through the medium outlet 6, causing the pressure in the entire pipeline to gradually decrease.

[0061] S4: When the medium pressure at medium inlet 4 gradually decreases from the set pressure to the normal pressure (i.e., the circuit pressure decreases from the set pressure to the normal pressure), the main valve core 1 and the auxiliary valve core 2 move downwards simultaneously until the initial state, and the valve core structure of the combined safety valve gradually returns to the closed state.

[0062] First, as the medium pressure at medium inlet 4 decreases, the upward medium force acting on the auxiliary valve core 2 gradually decreases until it is less than the downward force exerted by the lower spring 3 on the auxiliary valve core 2. At this point, the auxiliary valve core 2 moves back to the lower limit position (i.e., the initial state) within the main valve core 1. At this time, the branch pipe 5 is connected to the pressure chamber 10, but most of the medium is still discharged directly from the medium outlet 6 through the main valve core seat 8. As some medium enters the branch pipe 5, and the pressure in the entire pipeline continuously decreases due to the venting, the upward medium force acting on the main valve core 1 gradually decreases until it is less than the downward spring force of the upper spring 13. At this point, the main valve core 1 gradually moves downward, causing the venting channel formed between the main valve core 1 and the main valve core seat 8 to gradually narrow. Simultaneously, the medium enters the pressure chamber 10 through the branch pipe 5. The downward medium force on the upper surface of the main valve core 1 gradually increases, and it is also subjected to a downward spring force from the upper spring 13. The main valve core 1, together with the auxiliary valve core 2, moves downward synchronously until it is completely closed and returns to the initial state of S1.

[0063] This invention solves the problems of slow response, insufficient sealing performance, and complex structure of traditional safety valves. Traditional pilot-operated safety valves rely on multi-stage valve body linkage, resulting in delayed response and high manufacturing costs; while direct-start safety valves have fast response, poor sealing performance can easily lead to abnormal tripping. This invention proposes a novel combined structure by integrating a secondary valve core, upper and lower springs, and a vent hole inside the main valve core: In the closed state, the main valve core is pressed tightly against the valve seat due to the area difference and medium pressure, while the secondary valve core remains sealed under the action of spring force; when the pressure reaches the set value, the secondary valve core opens first, releasing the medium in the pressure chamber through the vent hole, triggering the main valve core to open rapidly, thus achieving overpressure protection. This invention combines the advantages of high sealing performance of pilot-operated valves and rapid response of direct-start valves, with a compact structure and low manufacturing cost, making it suitable for high-pressure, high-reliability scenarios such as nuclear power and chemical industries.

[0064] 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 method of using a combined safety valve core structure with pilot function, characterized in that, The pilot-operated combined safety valve core structure includes a main valve core (1) and a secondary valve core (2) coaxially mounted inside the valve body (12). The main valve core (1) is slidably and sealed to the inner wall of the valve body (12). A stepped through hole is axially opened in the middle, and a secondary valve core (2) is slidably and sealed to the through hole. The through hole includes three sections from top to bottom. The first section is used to limit the lower limit position of the secondary valve core (2) in the main valve core (1). The second section has a gap with the secondary valve core (2) and is connected to the medium outlet (6) through the vent hole (7) opened on the main valve core (1). A lower spring (3) is sleeved on the outside of the secondary valve core (2) in the third section. A medium outlet (6) is opened on one side of the valve body (12), and a main valve core seat (8) is provided at the bottom. When the main valve core (1) is in the lower limit position, it can cooperate with the main valve core seat (8) to achieve a tight seal. The main valve core (1) is sealed, and the upper end face of the main valve core (1) and the top of the inner wall of the valve body (12) form a pressure chamber (10). The bottom medium inlet (4) of the valve body (12) is connected to the pressure chamber (10) through the branch pipe (5). The pressure chamber (10) is provided with an upper spring (13), and the two ends of the upper spring (13) are in contact with the top of the inner wall of the valve body (12) and the upper end face of the main valve core (1), respectively. The branch pipe (5) is connected to the top of the valve body (12) with a secondary valve core seat (9). When the secondary valve core (2) is in the upper limit position, it can cooperate with the secondary valve core seat (9) to achieve a seal. The upper end face area of ​​the main valve core (1) is larger than its lower end face area, and the upper end face area of ​​the secondary valve core (2) is smaller than its lower end face area. The specific usage method is as follows: S1: When the medium pressure at the medium inlet is the normal pressure, the main valve core is in the lower limit position, the auxiliary valve core is in the lower limit position inside the main valve core, and the combined safety valve core structure is in the closed state; the medium enters through the medium inlet and fills the pipeline, and at the same time, the medium fills the pressure chamber through the branch pipe; Because the upper end face area of ​​the main valve core is larger than its lower end face area, a downward medium force is generated under the pressure of the same medium. At the same time, the upper spring is in a compressed state and applies a downward spring force to the upper end face of the main valve core, so that the lower end face of the main valve core is tightly pressed onto the main valve core seat, ensuring the sealing performance of the entire circuit. The lower spring is in a compressed state at this time and exerts a downward force on the auxiliary valve core. Although the lower end face area of ​​the secondary valve core is larger than that of the upper end face area, resulting in an upward medium force on the secondary valve core under the action of the medium, in this state, the upward medium force on the secondary valve core is less than the downward spring force of the lower spring, allowing the secondary valve core to make tight contact with the main valve core under the total downward force, thus achieving a seal; at this time, although the lower spring exerts an upward spring force on the main valve core, this spring force is less than the medium force on the main valve core due to the difference in the upper and lower end face areas, thus preventing the main valve core from moving upward; S2: When the medium pressure at the medium inlet gradually increases, both the main valve core and the auxiliary valve core gradually move upward, and the valve core structure of the combined safety valve is in the upward opening state; At the beginning of S2, the main valve core is still subjected to the downward medium force, which in turn seals with the main valve core seat. At this point, because the lower end face area of ​​the secondary valve core is larger than the upper end face area, and the medium pressure is also higher, the upward medium force on the secondary valve core in this state is greater than the downward spring force of the lower spring, causing the secondary valve core to move upward and the lower spring to be further compressed. When the secondary valve core moves upward to the secondary valve core seat, it is limited and stops moving, and makes tight contact with the secondary valve core seat to achieve a seal, cutting off the connection between the branch pipe and the pressure chamber. As the secondary valve core moves upward, the medium in the pressure chamber flows into the main valve core through hole and is discharged from the valve body through the medium outlet via the vent hole. After the medium in the pressure chamber is discharged, the pressure inside the pressure chamber decreases. At this time, the upward medium pressure on the lower end face of the main valve core is greater than the sum of the downward medium pressure and the spring force on the upper end face, causing the main valve core to gradually move upward under the action of the upward medium force and achieve opening. After the main valve core moves upward, the medium at the medium inlet is directly discharged in large quantities from the medium outlet through the main valve core seat, reducing the pressure of the entire pipeline and thus achieving overpressure protection. S3: When the medium pressure at the medium inlet rises to the set pressure, both the main valve core and the auxiliary valve core are at their upper limit positions, and the valve core structure of the combined safety valve is in a fully open state. The auxiliary valve core remains in close contact with the auxiliary valve core seat. At the same time, the upper spring is in a compressed state. The upward medium force and the downward spring force on the main valve core are balanced, and a stable medium discharge outlet is formed between the lower end face and the main valve core seat. The medium at the medium inlet is continuously discharged through the medium outlet, causing the pressure in the entire pipeline to gradually decrease. S4: When the medium pressure at the medium inlet gradually decreases from the set pressure to the normal pressure, the main valve core and the auxiliary valve core move downwards simultaneously until the initial state is reached, and the valve core structure of the combined safety valve gradually returns to the closed state.

2. The method of use according to claim 1, characterized in that, The upper part of the main valve core (1) is provided with a third sealing ring (11-c) along the circumferential direction to achieve a seal with the inner wall of the valve body (12).

3. The method of use according to claim 1, characterized in that, The outer periphery of the auxiliary valve core (2) located at the first and third sections of the through hole is provided with a second sealing ring (11-b) and a first sealing ring (11-a) respectively, so as to achieve a sealed connection with the main valve core (1).

4. The method of use according to claim 1, characterized in that, The effective distance that the lower spring (3) can compress during use is greater than the distance from the upper surface of the secondary valve core (2) to the secondary valve core seat (9).

5. The method of use according to claim 1, characterized in that, The lower end face of the main valve core (1) and the top face of the main valve core seat (8) are both set as conical surfaces that can cooperate with each other to increase the sealing performance.

6. The method of use according to claim 1, characterized in that, The upper surface of the secondary valve core (2) and the bottom surface of the secondary valve core seat (9) are both set as conical surfaces that can cooperate with each other to increase the sealing performance.

7. The method of use according to claim 1, characterized in that, The lower part of the secondary valve core (2) has a T-shaped structure, and the lower spring (3) is limited by the inner wall of the connection between the bottom of the secondary valve core (2) and the second and third sections of the through hole of the main valve core (1).

8. The method of use according to claim 1, characterized in that, The main valve core (1), the auxiliary valve core (2), the lower spring (3), the upper spring (13), the main valve core seat (8), the auxiliary valve core seat (9), and the valve body (12) are all coaxially arranged.

9. The method of use according to claim 1, characterized in that, Both the upper spring (13) and the lower spring (3) are always in a compressed state.

10. The method of use according to claim 1, characterized in that, S4 is specifically as follows: As the medium pressure at the medium inlet decreases, the upward medium force acting on the auxiliary valve core gradually decreases until it is less than the downward force exerted by the lower spring on the auxiliary valve core. At this point, the auxiliary valve core moves back to the lower limit position within the main valve core. At this time, the branch pipe is connected to the pressure chamber, but most of the medium is still discharged directly from the medium outlet through the main valve core seat. As some medium enters the branch pipe, and the pressure in the entire pipeline continuously decreases due to the venting, the upward medium force acting on the main valve core gradually decreases until it is less than the downward spring force of the upper spring. The main valve core gradually moves downward, causing the venting channel formed between the main valve core and the main valve core seat to gradually narrow. Simultaneously, the medium enters the pressure chamber through the branch pipe, and the downward medium force on the upper end face of the main valve core gradually increases. Under the action of the downward spring force of the upper spring, the main valve core, together with the auxiliary valve core, moves downward synchronously until it is completely closed and returns to the initial state of S1.

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