A pilot safety valve

Abstract

The present invention provides a pilot safety valve, comprising a valve body, a main valve core, a valve cover, a first elastic member, a diaphragm and a locking member, wherein the inner side of the valve body has a first channel, a second channel and a third channel, and the two ends are provided with a first groove and a second groove, the main valve core is located inside the valve body, the first end is located in the first groove, the second end passes through the first channel, the interior of the main valve core is provided with a channel hole connected to the second channel, and the channel hole is connected to the second groove; the valve cover is fixedly connected to the valve body, the valve cover and the second groove define a cavity, the valve cover is provided with an exhaust hole, and the aperture of the exhaust hole is smaller than the aperture of the channel hole; the first elastic member, the diaphragm and the locking member are located in the cavity, the first elastic member is used to apply a pulling force to the main valve core, so that the first end of the main valve core closes the first channel, the opening airflow enters the cavity through the third channel and the channel hole, and the back pressure is applied to the diaphragm to push the main valve core to open the valve inlet. The valve can improve the adjustment accuracy and reliability.

Description

Technical Field

[0001] The invention relates to the technical field of power system valves, and in particular to a pilot-operated safety valve. Background Art

[0002] With the rapid development of the aerospace industry, various technologies involved in the rocket field have also achieved rapid progress. The safety valve is an important component of the self-generated booster delivery system of the liquid rocket engine and plays an important role in the booster circuit. The safety valve is installed at the outlet of the pressure reducing valve. Its function is to open the exhaust system to restore the pressure of the pressure reducing valve outlet to a safe range when the pressure at the pressure reducing valve outlet is overshot, and close the valve of the safety valve to protect the safety of the system. The usual design scheme is to use a direct-acting safety valve to achieve sealing and safe discharge. However, this scheme is suitable for systems with a large opening and closing pressure difference. For systems with as small an opening and closing pressure difference as possible, it is difficult to take into account the pressure accuracy requirements of sealing, opening and returning to the seat using a direct-acting safety valve, which greatly reduces the reliability and safety of the system.

[0003] Therefore, there is an urgent need to provide a safety valve that can improve the adjustment accuracy and reliability and ensure the safe operation of the liquid rocket engine. Summary of the invention

[0004] The purpose of the present invention is to overcome the deficiencies of the prior art and provide a pilot-operated safety valve that can improve the regulation accuracy and reliability, ensure the safe operation of a liquid rocket engine, and thus improve the working reliability and efficiency of the liquid rocket engine.

[0005] One aspect of the present invention provides a pilot-operated safety valve, comprising a valve body, a main valve core, a valve cover, a first elastic member, a diaphragm and a locking member, wherein:

[0006] The inner side of the valve body is provided with a first channel, a second channel and a third channel extending in a different direction from the first channel for gas medium to flow, and two ends of the valve body are respectively provided with a first groove and a second groove concave toward the center of the valve body, and the first groove and the second groove are connected through the first channel;

[0007] The main valve core is located inside the valve body, with a first end thereof located in the first groove, and a second end thereof penetrating the first channel. A channel hole communicating with the second channel is provided inside the main valve core and close to the second groove, and an end of the channel hole away from the second channel is communicated with the second groove;

[0008] The valve cover is fixedly connected to the valve body, the valve cover and the second groove define a cavity, the valve cover is provided with an exhaust hole, and the aperture of the exhaust hole is smaller than the aperture of the channel hole;

[0009] The first elastic member, the diaphragm and the locking member are located in the cavity, and the first elastic member, the diaphragm and the locking member are respectively sleeved on the main valve core, the diaphragm is fixed to the main valve core through the locking member, the diaphragm abuts against the bottom of the second groove along the outer end surface circumferentially, and one end of the first elastic member abuts against the side of the diaphragm close to the first elastic member;

[0010] The first elastic member is used to apply a pulling force to the main valve core, so that the first end of the main valve core closes the first channel, opens the air flow through the second channel and the channel hole into the cavity, and applies back pressure to the diaphragm to push the main valve core to open the valve inlet.

[0011] Furthermore, the main valve core includes a first valve core portion and a second valve core portion of an integrally formed design, the first valve core portion and the second valve core portion are cylindrical structures in appearance, and the diameter of the first valve core portion is larger than the aperture of the first channel, the circumferential outer surface of the second valve core portion is tightly attached to the inner wall of the first channel and can move freely inside the first channel; the first valve core portion is tightly attached to / separated from the bottom of the first groove, thereby realizing the closing / conducting of the first channel and the third channel.

[0012] Furthermore, at least two sealing rings are disposed on the circumferential surface of the second valve core portion, and the two sealing rings are located on both sides of the connection between the second channel and the channel hole.

[0013] Furthermore, an annular inner groove for cooperating and fixing the sealing ring is provided on the first channel wall, the inner side of the sealing ring is in close contact with the outer surface of the second valve core portion, and the outer side of the sealing ring is located in the annular inner groove.

[0014] Furthermore, an annular sealing gasket and an annular groove for cooperating and fixing the annular sealing gasket are provided on one side of the first valve core portion close to the bottom of the first groove.

[0015] Furthermore, a boss is provided on the valve body, and the boss is a structure in which the valve body protrudes inward and then protrudes toward the valve cover, and the inner side of the boss forms a part of the first channel, and an annular groove is formed between the outer side and the inner wall of the valve body. The first elastic member is sleeved on the boss, and one end of the first elastic member abuts against the bottom of the annular groove, and the other end abuts against an end of the diaphragm away from the valve cover.

[0016] Furthermore, the valve body has a first part with a first diameter and a second part with a second diameter in sequence on its inner side from the side matching with the valve cover to the first groove, and the first diameter is larger than the second diameter, so that the diaphragm abuts against the table surface where the first part transitions to the second part.

[0017] Furthermore, the valve cover is further provided with a recess, a second elastic member and an auxiliary valve core, the recess is located in the middle of the valve cover and faces the main valve core, the second elastic member and the auxiliary valve core are located inside the recess, one end of the second elastic member abuts against the bottom surface of the recess, and the other end is connected to the auxiliary valve core. The second elastic member is used to apply pressure to the auxiliary valve core so that the auxiliary valve core closes the channel hole of the main valve core.

[0018] Furthermore, the axis of the auxiliary valve core coincides with the axis of the first channel, and one end of the auxiliary valve core abuts against the main valve core.

[0019] Furthermore, the circumferential outer surface of the valve cover is provided with an external thread, and the inner side of the valve body is provided with an internal thread matching the external thread; the valve cover is a cylindrical structure; the first elastic member and the second elastic member are springs; and the locking member is a locking nut.

[0020] A pilot-operated safety valve provided in an embodiment of the present invention is composed of a valve body, a main valve core, a valve cover, a first elastic member, a diaphragm and a locking member.

[0021] In the initial state, the safety valve is in a closed state, that is, the main valve core is closed, and the first channel is not connected to the third channel. When a small amount of gas medium enters the valve body, the gas medium first enters the channel hole inside the main valve core through the second channel, and then the gas medium enters the cavity. Since the aperture of the exhaust hole is smaller than the aperture of the channel hole, the gas medium entering the cavity from the channel hole is greater than the gas medium flowing out from the exhaust hole, which in turn causes the amount of gas medium in the cavity to increase, causing the pressure in the cavity to increase, and the pressure will exert back pressure on the diaphragm to push the main valve core to open the valve inlet, so that the first channel and the third channel are connected, so that the gas medium is quickly discharged from the third channel to the outside of the valve body.

[0022] When the gas medium in the valve body decreases, that is, the pressure exerted by the gas medium entering the cavity on the back of the diaphragm is less than the pressure exerted by the first elastic member on the front of the diaphragm, the elastic member can push the main valve core to close the valve inlet. In addition, by designing that the first elastic member, the diaphragm and the locking member are respectively sleeved on the main valve core, the first elastic member and the diaphragm can be prevented from radial movement, which facilitates the first elastic member to quickly exert pressure on the diaphragm, so as to increase the adjustment rate of the valve, thereby improving the working efficiency of the valve.

[0023] The design of the entire safety valve can improve the adjustment accuracy and reliability, ensure the safe operation of the liquid rocket engine, and thus improve the working reliability and efficiency of the liquid rocket engine.

[0024] It should be understood that the above general description and the following detailed description are merely exemplary and illustrative and are not intended to limit the scope of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] The following drawings are part of the specification of the present invention, and illustrate exemplary embodiments of the present invention. Together with the description of the specification, the accompanying drawings are used to explain the principles of the present invention.

[0026] Figure 1 It is a structural schematic diagram of the pilot-operated safety valve of the present invention;

[0027] Figure 2 It is a cross-sectional schematic diagram of the valve body, main valve core and valve cover of the present invention;

[0028] Figure 3 It is a structural schematic diagram of the valve body and the main valve core of the present invention;

[0029] Figure 4 It is a structural schematic diagram of the valve cover of the present invention;

[0030] Figure 5 It is a structural schematic diagram of the main valve core of the present invention;

[0031] Figure 6 It is a three-dimensional diagram of the boss of the present invention.

[0032] Description of reference numerals:

[0033] 1 Valve body 2 Main valve core

[0034] 3 valve cover 4 first elastic member

[0035] 5 diaphragm 6 locking piece

[0036] 7 First channel 8 Second channel

[0037] 9 first groove 10 second groove

[0038] 11 channel hole 12 exhaust hole

[0039] 13 boss 14 cavity

[0040] 15 sealing ring 16 first valve core part

[0041] 17 second valve core portion 18 annular inner groove

[0042] 19 channel cavity 20 annular groove

[0043] 21 table top 22 concave part

[0044] 23 second elastic member 24 auxiliary valve core

[0045] 25Third Channel DETAILED DESCRIPTION

[0046] Various exemplary embodiments of the present invention will now be described in detail. This detailed description should not be considered as limiting the present invention, but should be understood as a more detailed description of certain aspects, features, and embodiments of the present invention.

[0047] It will be apparent to those skilled in the art that various modifications and variations may be made to the specific embodiments of the present invention description without departing from the scope or spirit of the present invention. Other embodiments derived from the present invention description will be apparent to those skilled in the art. The present application description and examples are exemplary only.

[0048] One aspect of the present invention provides a pilot-operated safety valve. Figure 1 , Figure 2 , Figure 3 , Figure 4 and Figure 5 As shown, the safety valve comprises a valve body 1, a main valve core 2, a valve cover 3, a first elastic member 4, a diaphragm 5 and a locking member 6. The inner side of the valve body 1 is provided with a first channel 7, a second channel 8 and a third channel 25 extending in a different direction from the first channel 7 for the flow of gas medium, and the two ends of the valve body 1 are respectively provided with a first groove 9 and a second groove 10 recessed toward the center of the valve body 1, and the first groove 9 and the second groove 10 are connected through the first channel 7 (the space of the first groove 9 constitutes a part of the first channel 7 of the valve body 1). The main valve core 2 is located on the inner side of the valve body 1, with its first end located in the first groove 9 and its second end passing through the first channel 7. A channel hole 11 connected to the second channel 8 is provided inside the main valve core 2 and close to the second groove 10. The channel hole 11 is connected to the second groove 10 at the end away from the second channel 8.

[0049] The valve cover 3 is fixedly connected to the valve body 1 . The valve cover 3 , the diaphragm 5 and the second groove 10 define a cavity 14 . The valve cover 3 is provided with an exhaust hole 12 , and the aperture of the exhaust hole 12 is smaller than the aperture of the channel hole 11 .

[0050] The first elastic member 4, the diaphragm 5 and the locking member 6 are located in the cavity 14, and the first elastic member 4, the diaphragm 5 and the locking member 6 are respectively sleeved on the main valve core 2, the diaphragm 5 is fixedly arranged on the main valve core 2 through the locking member 6, the diaphragm 5 abuts against the bottom of the second groove 10 along the outer end surface circumferentially, and one end of the first elastic member 4 abuts against the side of the diaphragm 5 close to the first elastic member 4. The side of the main valve core close to the valve cover 3 extends out from the middle opening of the diaphragm 5, the locking member 6 locks the diaphragm 5 from the extended part of the main valve core 2, and the first elastic member 4 is arranged on the other side of the diaphragm 5.

[0051] The first elastic member 4 is used to apply tension to the main valve core 2, so that the first end of the main valve core 2 closes the first channel 7, opens the air flow through the second channel 8 and the channel hole 11 into the cavity 14, and applies back pressure to the diaphragm 5 to push the main valve core 2 to open the valve inlet.

[0052] Specifically, the pilot-operated safety valve is composed of a valve body 1 , a main valve core 2 , a valve cover 3 , a first elastic member 4 , a diaphragm 5 and a locking member 6 .

[0053] In the initial state, the safety valve is in a closed state, that is, the main valve core 2 is closed, and the first channel 7 is not connected to the third channel 25. When a small amount of gas medium enters the valve body, the gas medium first enters the channel hole inside the main valve core through the second channel 8, and then the gas medium enters the cavity 14. Since the aperture of the exhaust hole 12 is smaller than the aperture of the channel hole 11, the gas medium entering the cavity 14 from the channel hole 11 is greater than the gas medium flowing out from the exhaust hole 12, which in turn causes the amount of gas medium in the cavity 14 to increase, so that the pressure in the cavity 14 increases, and the pressure will exert back pressure on the diaphragm 5 to push the main valve core 2 to open the valve inlet, so that the first channel 7 and the third channel 25 are connected, so that the gas medium is quickly discharged from the third channel 25 to the outside of the valve body.

[0054] When the gas medium in the valve body 1 decreases, that is, the pressure exerted by the gas medium entering the cavity 14 on the back of the diaphragm 5 is less than the pressure exerted by the first elastic member 4 on the front of the diaphragm 5, the first elastic member 4 can push the main valve core 2 to close the valve inlet. In addition, the design of the first groove 9 and the second groove 10 can facilitate the installation of the valve body 1 and various components in the valve body 1. In addition, the safety valve of the present application can avoid radial movement of the first elastic member 4 and the diaphragm 5 by the design that the first elastic member 4, the diaphragm 5 and the locking member 6 are respectively sleeved on the main valve core 2, so as to facilitate the first elastic member 4 to quickly apply pressure to the diaphragm 5, so as to increase the adjustment rate of the valve, thereby improving the working efficiency of the valve. The entire design can improve the adjustment accuracy and reliability of the safety valve, ensure the safe operation of the liquid rocket engine, and thus improve the working reliability and efficiency of the liquid rocket engine.

[0055] It should be noted that, in order to facilitate the movement of the main valve core 2 and to facilitate the main valve core 2 to seal the first channel 7, for example, the main valve core 2 includes a first valve core portion 16 and a second valve core portion 17, and the first valve core portion 16 and the second valve core portion 17 are cylindrical in shape, and the diameter of the first valve core portion 16 is larger than the aperture of the first channel 7. The circumferential outer surface of the second valve core portion 17 is in close contact with the inner wall of the first channel 7 and can move freely inside the first channel 7. The first valve core portion 16 is in close contact with / separated from the bottom of the first groove 9 (the surface of the first valve core portion 16 and the first groove 9 on the side close to each other) to achieve the closing / conducting of the first channel 7 and the third channel 25. In order to make the first valve core portion 16 and the second valve core portion 17 tightly connected and more firmly fixed, for example, the first valve core portion 16 and the second valve core portion 17 are designed to be integrally formed.

[0056] It is worth noting that in order to prevent the gas medium from leaking into the first channel 7 from the gap at the connection between the second channel 8 and the channel hole 11, for example, at least two sealing rings are provided on the circumferential surface of the second valve core portion 17, and the two sealing rings 15 are separated on both sides of the connection between the second channel 8 and the channel hole 11, which can reduce the outflow of the gas medium from the gap between the inner surface of the first channel 7 and the outer surface of the second valve core portion 17, ensure that the gas medium quickly acts on the cavity, complete the expansion of the back of the diaphragm 5 (bending toward the side of the first valve core portion 16) and the opening of the main valve core 2, and ensure the rapid connection between the first channel 7 and the third channel 25.

[0057] It should be noted that in order to avoid axial movement of the sealing ring 15 and facilitate the fixation of the sealing ring 15, for example, an annular inner groove 18 is provided on the wall of the first channel 7 to cooperate with and fix the sealing ring 15. The inner side of the sealing ring 15 is tightly attached to the outer surface of the second valve core portion 17, and the outer side of the sealing ring 15 is located in the annular inner groove 18.

[0058] In addition, in order to improve the sealing performance of the medium inlet and reduce the direct contact between the first valve core 16 and the end surface of the first channel 7, an annular sealing gasket is provided on the first valve core 16 near the bottom of the first groove 9. The annular sealing gasket can reduce the damage of the first valve core 16 and the end surface of the first channel 7 caused by frequent opening and closing of the main valve core 2. In addition, in order to prevent the annular sealing gasket from falling off and improve the stability of the annular sealing gasket, for example, an annular groove 20 for cooperating and fixing the annular sealing gasket can be provided on the first valve core 16.

[0059] In addition, if Figure 1 , Figure 2 , Figure 3 and Figure 6 As shown, in order to facilitate the movement of the first elastic member 4, the first elastic member 4 quickly responds to the diaphragm 5 (reducing the force of the first elastic member 4 that is different from the axial direction). For example, a boss 13 is also provided on the side of the valve body 1 close to the second groove 10. The boss is a structure that protrudes inward from the valve body and then protrudes in the direction of the valve cover. The boss 13 is provided with a channel cavity 19 connected to the first channel 7. The inner side of the boss forms a part of the first channel (channel cavity 19), and an annular groove is formed between the outer side and the inner wall of the valve body 1. When used, the first elastic member is sleeved on the boss, one end of the first elastic member abuts against the bottom of the annular groove, and the other end abuts against the end of the diaphragm away from the valve cover. The annular groove can be used to fix one end of the first elastic member (abutting against the bottom of the annular groove) to prevent the first elastic member from moving to the side away from the valve cover. In addition, the first elastic member can move along the outer wall of the boss, and the boss acts as a guide rod to reduce the radial deviation of the first elastic member 4 and prevent the combined force of the first elastic member 4 moving in the axial direction from becoming smaller, thereby affecting the deformation of the diaphragm.

[0060] It is worth mentioning that, in order to facilitate the fixing of the diaphragm, for example, the valve body 1 is provided with a first part with a first diameter and a second part with a second diameter in sequence on the inner side from the side matching with the valve cover 3 to the first groove 9, and the first diameter is larger than the second diameter, so that the diaphragm 5 contacts the table surface where the first part transitions to the second part (the side of the diaphragm 5 close to the main valve core 2 is in close contact with the main valve core 2). The circumferential extension side of the diaphragm 5 is in close contact with the table surface, and the table surface and the end surface of the side of the valve cover 3 close to the diaphragm 5 clamp the diaphragm 5 between the table surface and the end surface, so that the extension side is fixed therein, thereby improving the stability of the diaphragm 5. In addition, in order to facilitate the deformation of the diaphragm 5 (the part of the middle part of the diaphragm 5 that is not clamped between the table surface and the end surface), the diaphragm 5 is an elastic metal sheet. In addition, the table is provided with a plurality of raised strips arranged in the radial direction (for example, the raised strips are evenly arranged on the table, the number of raised strips can be 3, and the angle between adjacent raised strips is 120°), and the diaphragm 5 is provided with a recessed portion for matching the raised strips, and the raised strips and the recessed portion achieve a concave-convex match, which can prevent the diaphragm 5 from making axial movement along the surface of the boss, thereby affecting the deformation of the diaphragm (the force on the diaphragm changes, that is, the resultant force decreases); on the other hand, when the pressure applied by the gas medium and the diaphragm increases, the diaphragm shrinks, that is, the outer side of the diaphragm approaches the center of the diaphragm, and when the pressure decreases, the diaphragm recovers along the raised strips (equivalent to the track). In order to make the diaphragm 5 and the main valve core 2 tightly connected and firmly fixed, for example, the diaphragm 5 and the main valve core 2 are connected by threads.

[0061] In this embodiment, in order to reduce the contact between the main valve core 2 and the valve cover 3 and avoid the damage of the main valve core 2 to the valve cover 3 due to frequent contact between the two, for example, the valve cover 3 is also provided with a recess 22, a second elastic member 23 and an auxiliary valve core 24. The recess 22 is located in the middle of the valve cover 3 and is arranged facing the main valve core 2, the second elastic member 23 and the auxiliary valve core 24 are located inside the recess 22, one end of the second elastic member 23 abuts against the bottom surface of the recess 22, and the other end is connected to the auxiliary valve core 24. The second elastic member 23 is used to apply pressure to the auxiliary valve core 24 so that the auxiliary valve core 24 closes the channel hole 11 of the main valve core 2. The cross-sectional end surfaces of the two ends of the auxiliary valve core 24 tangent to the axis of the auxiliary valve core 24 are convex, the large end side is connected to the main valve core 2, and the small end side is connected to the second elastic member 23. For example, during the movement of the auxiliary valve core 24, the large end side of the auxiliary valve core 24 can always be in the recess 22. In order to improve the stability of the movement of the auxiliary valve core 24 , for example, the circumferential surface of the large end of the auxiliary valve core 24 abuts against the inner surface of the recess 22 and can move freely along the inner surface of the recess 22 .

[0062] In addition, in order to facilitate the gas medium to drive the auxiliary valve core 24 to move, the axis of the auxiliary valve core 24 coincides with the axis of the first channel 7, and one end of the auxiliary valve core 24 abuts against the main valve core 2. During the whole process, the gas medium applies pressure to the auxiliary valve core 24, so that the auxiliary valve core 24 moves toward the side of the recess 22, so that a gap appears between the main valve core 2 and the auxiliary valve core 24 (the pressure applied by the gas medium to the auxiliary valve core 24 is large enough), thereby facilitating the gas medium to enter the cavity 14 through the second channel 8, the channel hole inside the main valve core, and the gap between the main valve core and the auxiliary valve core.

[0063] In addition, in order to allow the gas medium to quickly enter the first channel through the second channel 8, for example, the second channel 8 can be designed as a bending structure, that is, the second channel 8 includes a fourth channel arranged parallel to the first channel and a fifth channel connected to the fourth channel, one end of the fifth channel is connected to the channel hole, and the angles between the axis of the fourth channel and the axis of the fifth channel are 100°, 110°, and 120°. After a large number of simulation experiments, when the angle between the axis of the fourth channel and the axis of the fifth channel is A, and satisfies 100°≤A≤150°, the gas medium can quickly enter the channel hole, and at the same time, the impact of the gas medium on the fifth channel can be reduced, and the fifth channel can be effectively protected, thereby increasing the service life of the valve body.

[0064] In addition, in order to facilitate installation and disassembly, for example, the circumferential outer surface of the valve cover 3 is provided with an external thread, and the inner side of the valve body 1 is provided with an internal thread matching the external thread. In order to facilitate the installation of the valve cover 3 and reduce the weight of the valve cover 3, for example, the valve cover 3 is a cylindrical structure matching the inner side of the valve body 1.

[0065] In this embodiment, the first elastic member 4 and the second elastic member 23 are springs, and the locking member 6 is a locking nut.

[0066] The above embodiments can be combined with each other and have corresponding technical effects.

[0067] The above description is only an illustrative specific implementation manner of the present invention. Without departing from the concept and principle of the present invention, any equivalent changes and modifications made by those skilled in the art should fall within the scope of protection of the present invention.

Claims

1. A pilot-operated safety valve, characterized in that: It comprises a valve body, a main valve core, a valve cover, a first elastic member, a diaphragm and a locking member, wherein: The inner side of the valve body is provided with a first channel, a second channel and a third channel extending in a different direction from the first channel for gas medium to flow, and two ends of the valve body are respectively provided with a first groove and a second groove concave toward the center of the valve body, and the first groove and the second groove are connected through the first channel; The main valve core is located inside the valve body, with a first end thereof located in the first groove and a second end thereof penetrating the first channel. A channel hole communicating with the second channel is provided inside the main valve core and close to the second groove, and an end of the channel hole away from the second channel is communicated with the second groove. The valve cover is fixedly connected to the valve body, the valve cover and the second groove define a cavity, the valve cover is provided with an exhaust hole, and the aperture of the exhaust hole is smaller than the aperture of the channel hole; The first elastic member, the diaphragm and the locking member are located in the cavity, and the first elastic member, the diaphragm and the locking member are respectively sleeved on the main valve core, the diaphragm is fixed to the main valve core through the locking member, the diaphragm abuts against the bottom of the second groove along the outer end surface circumferentially, and one end of the first elastic member abuts against the side of the diaphragm close to the first elastic member; The first elastic member is used to apply a pulling force to the main valve core, so that the first end of the main valve core closes the first channel, and the air flow enters the cavity through the second channel and the channel hole, and applies back pressure to the diaphragm to push the main valve core to open the valve inlet; the main valve core includes a first valve core part and a second valve core part of an integrally formed design, the first valve core part and the second valve core part have a cylindrical structure, and the diameter of the first valve core part is larger than the aperture of the first channel, the circumferential outer surface of the second valve core part is tightly attached to the inner wall of the first channel and can move freely inside the first channel; the first valve core part is tightly attached to / separated from the bottom of the first groove to achieve the closing / conducting of the first channel and the third channel.

2. The pilot operated safety valve according to claim 1, characterized in that: At least two sealing rings are disposed on the circumferential surface of the second valve core portion, and the two sealing rings are located on both sides of the connection point between the second channel and the channel hole.

3. The pilot operated safety valve according to claim 2, characterized in that: The first channel wall is provided with an annular inner groove for cooperating and fixing the sealing ring, the inner side of the sealing ring is in close contact with the outer surface of the second valve core part, and the outer side of the sealing ring is located in the annular inner groove.

4. The pilot operated safety valve according to claim 1, characterized in that: An annular sealing gasket and an annular groove for cooperating and fixing the annular sealing gasket are provided on one side of the first valve core portion close to the bottom of the first groove.

5. The pilot operated safety valve according to claim 1, characterized in that: The valve body is also provided with a boss, which is a structure that protrudes inwardly from the valve body and then protrudes toward the valve cover, and the inner side of the boss forms a part of the first channel, and an annular groove is formed between the outer side and the inner wall of the valve body. The first elastic member is sleeved on the boss, and one end of the first elastic member abuts against the bottom of the annular groove, and the other end abuts against one end of the diaphragm away from the valve cover.

6. The pilot operated safety valve according to claim 1, characterized in that: The valve body has a first part with a first diameter and a second part with a second diameter in sequence on its inner side from the side matching with the valve cover to the first groove. The first diameter is larger than the second diameter, so that the diaphragm abuts against the table surface where the first part transitions to the second part.

7. The pilot operated safety valve according to claim 1, characterized in that: The valve cover is also provided with a recess, a second elastic member and an auxiliary valve core. The recess is located in the middle of the valve cover and faces the main valve core. The second elastic member and the auxiliary valve core are located on the inner side of the recess. One end of the second elastic member abuts against the bottom surface of the recess, and the other end is connected to the auxiliary valve core. The second elastic member is used to apply pressure to the auxiliary valve core so that the auxiliary valve core closes the channel hole of the main valve core.

8. The pilot operated safety valve according to claim 7, characterized in that: The axis of the secondary valve core coincides with the axis of the first passage.

9. The pilot operated safety valve according to claim 7, characterized in that: The circumferential outer surface of the valve cover is provided with an external thread, and the inner side of the valve body is provided with an internal thread matching the external thread; the valve cover is a cylindrical structure matching the inner side of the valve body; the first elastic member and the second elastic member are springs; and the locking member is a locking nut.

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