Breather valve capable of overcoming back pressure

Abstract

The utility model relates to a breather valve capable of overcoming back pressure, and belongs to the technical field of chemical production. The main cavity, the exhalation cavity and the suction cavity are internally arranged, the exhalation outlet flange, the suction inlet flange and the connector flange are externally connected to form the breather valve body, and meanwhile the exhalation pilot device and the suction pilot device are arranged and connected with the breather valve body. The self-adaptive exhalation and inhalation actions can be realized by combining the action of the balance spring and the air cylinder, the function of overcoming the back pressure of the exhalation side and the inhalation side is realized, and the internal and external air pressure environments are effectively balanced. In addition, exhaling and inhaling pressure can be accurately adjusted by adjusting the spring strength of the pilot device and the air cylinder, the problem that control over the pressure difference in a traditional breather valve is not accurate is solved, and meanwhile the sealing performance can be guaranteed through the arrangement of a sealing gasket.

Description

Technical Field

[0001] The utility model relates to a breathing valve for overcoming back pressure, belonging to the technical field of chemical production. Background Art

[0002] In the chemical production process, the breathing valve is a frequently used pipe fitting for balancing the air pressure. However, in actual use, there is often a phenomenon that the breathing valve does not open normally due to back pressure at the exhalation or inhalation port. This phenomenon may cause the breathing valve to lose its shielding function, resulting in the loss of oil and gas or nitrogen sealing nitrogen, or even a safety accident.

[0003] At present, the mainstream solution to this situation is to control the back pressure. For example, if there is negative pressure generated by the fan of the exhaust gas treatment equipment in the exhalation outlet pipe, the pressure difference between the exhalation pipe and the protected device must be strictly controlled to avoid abnormal opening of the valve plate. The solution on the suction side is similar. However, the problem brought by this solution is that the pressure of the suction pipe and the exhalation pipe must be controlled very accurately, which is difficult to achieve in actual production. Utility Model Content

[0004] In order to solve the above problems, the utility model provides a breathing valve for overcoming back pressure, comprising:

[0005] A breathing valve body, wherein different positions of the breathing valve body are respectively connected with an interface flange, an exhalation outlet flange, and an inhalation inlet flange; the interior of the breathing valve body includes a main cavity connected with the interface flange, an exhalation cavity connected with the main cavity and the exhalation outlet flange, and an inhalation cavity connected with the inhalation inlet flange, wherein the inhalation cavity is located inside the main cavity, and the main cavity is connected with the exhalation cavity and the inhalation cavity; the exhalation cavity and the inhalation cavity are respectively provided with a movable exhalation cylinder and a movable inhalation cylinder;

[0006] An exhalation pilot device is connected to the main cavity and the exhalation cavity; the exhalation pilot device has an exhalation pilot cavity that allows communication with the outside world, and an exhalation pilot piston is arranged in the exhalation pilot cavity;

[0007] The suction pilot device is connected to the main cavity and the suction cavity; the suction pilot device has a suction pilot cavity that allows communication with the outside, and a suction pilot piston is arranged in the suction pilot cavity.

[0008] Furthermore, the surfaces of the exhalation cylinder and the inhalation cylinder are respectively provided with an exhalation sealing pad and an inhalation sealing pad, the exhalation cylinder cooperates with the inner wall of the exhalation cavity through the exhalation sealing pad, and the inhalation cylinder cooperates with the inhalation cavity through the inhalation sealing pad;

[0009] The exhalation outlet flange is connected to the inner wall of the exhalation cavity that cooperates with the exhalation sealing pad, allowing the exhalation cylinder to open or completely close the exhalation outlet flange by moving along the inner wall of the exhalation cavity; the inlet flange is connected to the inner wall of the inhalation cavity that cooperates with the inhalation sealing pad, allowing the inhalation cylinder to open or completely close the inlet flange by moving along the inner wall of the inhalation cavity.

[0010] Furthermore, the exhalation cavity is connected to the main cavity via a first opening, which is located on the inner wall of the exhalation cavity that is not matched with the exhalation sealing pad; the inhalation cavity is provided with a second opening on the inner wall that is not matched with the inhalation sealing pad, and the inhalation cavity is provided with a third opening on the inner wall that is matched with the inhalation cylinder, and an inhalation spring is connected between the second opening and the inhalation cylinder.

[0011] Furthermore, an exhalation pilot piston is arranged in the exhalation pilot cavity, and the exhalation pilot piston includes a lower sealing gasket of the exhalation pilot piston, an upper sealing gasket of the exhalation pilot piston, and an exhalation pilot connecting rod connecting the lower sealing gasket of the exhalation pilot piston and the upper sealing gasket of the exhalation pilot piston; the lower sealing gasket of the exhalation pilot piston and the upper sealing gasket of the exhalation pilot piston are both matched with the inner wall of the exhalation pilot cavity and the diameter of the lower sealing gasket of the exhalation pilot piston is smaller than the diameter of the upper sealing gasket of the exhalation pilot piston; the exhalation pilot cavity is provided with at least one exhalation air pressure balance hole connected to the outside.

[0012] Further, the exhalation pilot cavity includes an exhalation pilot first cavity, an exhalation pilot second cavity, and an exhalation pilot third cavity which are connected in sequence, and the exhalation pilot piston lower sealing gasket, the exhalation pilot piston upper sealing gasket, and the exhalation pilot connecting rod are respectively matched with the exhalation pilot first cavity, the exhalation pilot second cavity, and the exhalation pilot third cavity. The exhalation pilot first cavity is connected to the exhalation cavity through the first exhalation air pipe, and the exhalation pilot second cavity is connected to the main cavity through the second exhalation air pipe.

[0013] Furthermore, a suction pilot piston is arranged in the suction pilot cavity, and the suction pilot piston includes a lower sealing gasket of the suction pilot piston, an upper sealing gasket of the suction pilot piston, and a suction pilot connecting rod connecting the lower sealing gasket of the suction pilot piston and the upper sealing gasket of the suction pilot piston; the lower sealing gasket of the suction pilot piston and the upper sealing gasket of the suction pilot piston are both matched with the inner wall of the suction pilot cavity and the diameter of the lower sealing gasket of the suction pilot piston is larger than the diameter of the upper sealing gasket of the suction pilot piston; the suction pilot cavity is provided with at least one suction air pressure balance hole connected to the outside.

[0014] Furthermore, the suction pilot cavity includes a suction pilot first cavity and a suction pilot second cavity connected in sequence, the suction pilot piston lower sealing gasket is matched with the suction pilot first cavity, the suction pilot piston upper sealing gasket and the suction pilot connecting rod are both matched with the suction pilot second cavity, and the suction pilot first cavity is connected to the suction cavity and the main cavity through the first suction air pipe and the second suction air pipe respectively.

[0015] Furthermore, the exhalation pilot first cavity and the inhalation pilot first cavity are respectively provided with an exhalation air pressure balance hole and an inhalation air pressure balance hole.

[0016] Furthermore, the exhalation pilot connecting rod and the inhalation pilot connecting rod are respectively sleeved with an exhalation pilot spring and an inhalation pilot spring.

[0017] Beneficial effects of the utility model:

[0018] The utility model constructs a breathing valve body by internally connecting a main cavity, an exhalation cavity, an inhalation cavity, and externally connecting an exhalation port flange, an inhalation port flange, and an interface flange. At the same time, an exhalation pilot device and an inhalation pilot device are provided to connect with the breathing valve body. The combined effect of a balance spring and a cylinder can realize adaptive exhalation and inhalation actions and has the function of overcoming the back pressure on the exhalation and inhalation sides, effectively balancing the internal and external air pressure environments. In addition, the exhalation and inhalation pressures can be precisely adjusted by adjusting the spring strength of the pilot device and the cylinder, solving the problem of inaccurate pressure difference control in traditional breathing valves. At the same time, the setting of the sealing pad can also ensure the sealing performance. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 This is a schematic diagram of the overall structure of an implementation method of the utility model;

[0020] In the figure: 1, breathing valve body; 2, interface flange; 3, exhalation outlet flange; 4, inhalation inlet flange; 5, exhalation pilot device; 6, inhalation pilot device; 71, first exhalation air pipe; 72, second exhalation air pipe; 81, first inhalation air pipe; 82, second inhalation air pipe;

[0021] 11. Main cavity; 12. Exhalation cavity; 13. Inhalation cavity; 14. Exhalation cylinder; 15. Inhalation cylinder; 141. Exhalation sealing pad; 151. Inhalation sealing pad; 16. Inhalation spring; 17. First port; 18. Second port; 19. Third port;

[0022] 51. Exhalation pilot piston lower seal; 52. Exhalation pilot piston upper seal; 53. Exhalation pilot connecting rod; 54. Exhalation air pressure balance hole; 55. Exhalation pilot spring;

[0023] 61. Suction pilot piston lower seal; 62. Suction pilot piston upper seal; 63. Suction pilot connecting rod; 64. Suction air pressure balance hole; 65. Suction pilot spring. DETAILED DESCRIPTION

[0024] The technical solution of the utility model will be described clearly and completely below in conjunction with the accompanying drawings. Obviously, the described embodiments are part of the embodiments of the utility model, not all of the embodiments. Based on the embodiments of the utility model, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the utility model.

[0025] In the description of the present invention, it should be noted that the terms "center", "up", "down", "left", "right", "vertical", "horizontal", "inside", "outside" and the like indicate positions or positional relationships based on the positions or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present invention. In addition, the terms "first" and "second" are used for descriptive purposes only, and cannot be understood as indicating or implying relative importance. Among them, the terms "first position" and "second position" are two different positions.

[0026] In the description of the present invention, it should be noted that, unless otherwise clearly specified and limited, the terms "installation", "connection" and "connection" should be understood in a broad sense, for example, it can be a fixed connection or a detachable connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium, or it can be the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0027] Example 1

[0028] like Figure 1 As shown, the utility model provides a breathing valve for overcoming back pressure, comprising:

[0029] A breathing valve body 1, wherein different positions of the breathing valve body 1 are respectively connected with an interface flange 2, an exhalation outlet flange 3, and an inhalation inlet flange 4; the breathing valve body 1 includes a main cavity 11 connected with the interface flange 2, an exhalation cavity 12 connected with the main cavity 11 and the exhalation outlet flange 3, and an inhalation cavity 13 connected with the inhalation inlet flange 4, wherein the inhalation cavity 13 is located inside the main cavity 11, and the main cavity 11 is connected with the exhalation cavity 12 and the inhalation cavity 13; the exhalation cavity 12 and the inhalation cavity 13 are respectively provided with a movable exhalation cylinder 14 and a movable inhalation cylinder 15;

[0030] The exhalation pilot device 5 is connected to the main cavity 11 and the exhalation cavity 12; the exhalation pilot device 5 has an exhalation pilot cavity that allows communication with the outside, and an exhalation pilot piston is arranged in the exhalation pilot cavity;

[0031] The suction pilot device 6 connects the main cavity 11 and the suction cavity 13; the suction pilot device 6 has a suction pilot cavity that allows communication with the outside, and a suction pilot piston is arranged in the suction pilot cavity.

[0032] Furthermore, the surfaces of the exhalation cylinder 14 and the inhalation cylinder 15 are respectively provided with an exhalation sealing pad 141 and an inhalation sealing pad 151, the exhalation cylinder 14 cooperates with the inner wall of the exhalation cavity 12 through the exhalation sealing pad 141, and the inhalation cylinder 15 cooperates with the inhalation cavity 13 through the inhalation sealing pad 151;

[0033] The exhalation outlet flange 3 is connected to the inner wall of the exhalation cavity 12 which cooperates with the exhalation sealing pad 141, allowing the exhalation cylinder 14 to open or completely close the exhalation outlet flange 3 by moving along the inner wall of the exhalation cavity 12; the inlet flange 4 is connected to the inner wall of the inhalation cavity 13 which cooperates with the inhalation sealing pad 151, allowing the inhalation cylinder 15 to open or completely close the inlet flange 4 by moving along the inner wall of the inhalation cavity 13.

[0034] Furthermore, the exhalation cavity 12 is connected to the main cavity 11 via a first opening 17, and the first opening 17 is located on the inner wall of the exhalation cavity 12 which is not matched with the exhalation sealing pad 141; the inhalation cavity 13 is provided with a second opening 18 on the inner wall which is not matched with the inhalation sealing pad 151, and the inhalation cavity 13 is provided with a third opening 19 on the inner wall which is matched with the inhalation cylinder 15, and an inhalation spring 16 is connected between the second opening 18 and the inhalation cylinder 15.

[0035] Furthermore, an exhalation pilot piston is provided in the exhalation pilot cavity, and the exhalation pilot piston includes an exhalation pilot piston lower sealing pad 51, an exhalation pilot piston upper sealing pad 52, and an exhalation pilot connecting rod 53 connecting the exhalation pilot piston lower sealing pad 51 and the exhalation pilot piston upper sealing pad 52; the exhalation pilot piston lower sealing pad 51 and the exhalation pilot piston upper sealing pad 52 are both matched with the inner wall of the exhalation pilot cavity, and the diameter of the exhalation pilot piston lower sealing pad 51 is smaller than the diameter of the exhalation pilot piston upper sealing pad 52;

[0036] Furthermore, the exhalation pilot cavity includes an exhalation pilot first cavity, an exhalation pilot second cavity, and an exhalation pilot third cavity which are connected in sequence. The exhalation pilot piston lower seal 51, the exhalation pilot piston upper seal 52, and the exhalation pilot connecting rod 53 are respectively matched with the exhalation pilot first cavity, the exhalation pilot second cavity, and the exhalation pilot third cavity. The exhalation pilot first cavity is connected to the exhalation cavity 12 through the first exhalation air pipe 71, and the exhalation pilot second cavity is connected to the main cavity 11 through the second exhalation air pipe 72.

[0037] Further, a suction pilot piston is arranged in the suction pilot cavity, and the suction pilot piston includes a suction pilot piston lower sealing pad 61, a suction pilot piston upper sealing pad 62, and a suction pilot connecting rod 63 connecting the suction pilot piston lower sealing pad 61 and the suction pilot piston upper sealing pad 62; the suction pilot piston lower sealing pad 61 and the suction pilot piston upper sealing pad 62 are both matched with the inner wall of the suction pilot cavity, and the diameter of the suction pilot piston lower sealing pad 61 is greater than the diameter of the suction pilot piston upper sealing pad 62;

[0038] Furthermore, the suction pilot cavity includes a suction pilot first cavity and a suction pilot second cavity connected in sequence, the suction pilot piston lower sealing gasket 61 is matched with the suction pilot first cavity, the suction pilot piston upper sealing gasket 62 and the suction pilot connecting rod 63 are both matched with the suction pilot second cavity, and the suction pilot first cavity is connected to the suction cavity 13 and the main cavity 11 through the first suction air pipe 81 and the second suction air pipe 82 respectively.

[0039] Furthermore, the exhalation pilot first cavity and the inhalation pilot first cavity are respectively provided with an exhalation air pressure balance hole 54 and an inhalation air pressure balance hole 64.

[0040] Furthermore, the exhalation pilot connecting rod 53 and the inhalation pilot connecting rod 63 are respectively sleeved with an exhalation pilot spring 55 and an inhalation pilot spring 65 .

[0041] The working principle of this utility model:

[0042] Call out process:

[0043] like Figure 1 As shown, first, the interface flange 2 is connected to the protected device. At this time, the pressures on the upper and lower sides of the exhalation cylinder 14 are equal. Due to gravity, the exhalation cylinder 14 is kept at the lowermost side of the exhalation cavity 12 (i.e., the first opening 17 is completely blocked);

[0044] Secondly, when the pressure of the protected device rises, the high-pressure gas passed to the main cavity 11 is conducted through the second exhalation air pipe 72 to between the lower seal 51 of the exhalation pilot piston and the upper seal 52 of the exhalation pilot piston of the exhalation pilot cavity, and then conducted through the first exhalation air pipe 71 to the upper space of the exhalation active cylinder in the exhalation cavity 12;

[0045] Next, when the air pressure rises further, since the diameter of the lower seal pad 51 of the exhalation pilot piston is smaller than the diameter of the upper seal pad 52 of the exhalation pilot piston, the pressure difference caused by the different surface areas of the seal pads can push the exhalation pilot piston to overcome the elastic force of the exhalation pilot spring 55, and drive the exhalation pilot connecting rod 54 to move upward together, until the height of the lower seal pad 51 of the exhalation pilot piston is higher than the height of the connection port of the first exhalation air pipe 71 at the location of the exhalation pilot device;

[0046] Then, the high-pressure gas in the upper space of the exhalation cylinder 14 in the exhalation cavity 12 is discharged to the outside through the first exhalation air pipe 71, the first exhalation pilot cavity, and the exhalation air pressure balance hole 54, and is restored to be equal to the external air pressure and then maintained;

[0047] Furthermore, as the air pressure of the protected device further increases, the exhalation cylinder 14 moves upward under the pressure difference between the upper and lower sides, and opens the exhalation outlet flange 3, the breathing valve body 1 performs the exhalation action, and the air pressure of the protected device is released. When the air pressure in the protected device and the breathing valve body 1 decreases, the exhalation cylinder 14 resets under the action of gravity, and the exhalation pilot piston resets under the action of the exhalation pilot spring 55 and returns to the initial state.

[0048] Inhalation process:

[0049] like Figure 1 As shown, first, the interface flange 2 is installed on the protected device. At this time, the pressures on the upper and lower sides of the suction cylinder 15 are equal, the upward pulling force of the suction spring 16 is balanced with the gravity, and the suction movable cylinder remains in place (i.e., the third port 19 is blocked); at the same time, because the diameter of the lower sealing gasket 61 of the suction pilot piston is larger than the diameter of the upper sealing gasket 62 of the suction pilot piston, the downward force generated by the air pressure difference caused by the surface area difference is balanced with the upward pulling force of the suction pilot spring 65, and the suction pilot piston also remains in place;

[0050] Secondly, when the pressure of the protected device drops, the high-pressure gas passed to the main cavity 11 is conducted by the second suction air pipe 82 to the suction pilot piston lower seal 61 and the suction pilot piston upper seal 62 of the suction pilot cavity, and then conducted by the first suction air pipe 81 to the lower side space of the suction cylinder in the suction cavity 13;

[0051] Then, when the air pressure drops further, the downward force of the suction pilot piston due to the upper and lower pressure difference decreases and is insufficient to resist the pulling force of the suction pilot spring 65. Therefore, the suction pilot piston will drive the suction pilot connecting rod 63 to move upward together until the height of the sealing gasket 61 under the suction pilot piston is higher than the height of the connection port of the first suction air pipe 81 at the suction pilot device.

[0052] Subsequently, gas is sucked from the outside into the lower space of the suction cylinder 15 in the suction cavity 13 through the first suction air pipe 81, the suction pilot first cavity, and the suction air pressure balance hole 64, and the pressure is kept equal to that of the outside.

[0053] Furthermore, as the air pressure in the protected device further drops, the pressure caused by the pressure difference between the upper and lower sides of the suction cylinder 15 causes it to move upward and open the suction port flange 4, the breathing valve body 1 performs the suction action, and the air pressure in the protected device is replenished; when the air pressure in the protected device and the breathing valve body 1 increases, the suction cylinder 15 is reset under the action of gravity, and the suction pilot piston is reset again under the action of the pressure difference to overcome the pulling force of the suction pilot spring 65, and the breathing valve body 1 returns to its initial state.

[0054] Although the present invention has been disclosed as above in terms of preferred embodiments, it is not intended to limit the present invention. Anyone familiar with the technology may make various changes and modifications without departing from the spirit and scope of the present invention. Therefore, the scope of protection of the present invention should be based on the definition of the claims.

Claims

1. A breathing valve for overcoming back pressure, characterized in that: include: A breathing valve body, wherein different positions of the breathing valve body are respectively connected with an interface flange, an exhalation outlet flange, and an inhalation inlet flange; the interior of the breathing valve body includes a main cavity connected with the interface flange, an exhalation cavity connected with the main cavity and the exhalation outlet flange, and an inhalation cavity connected with the inhalation inlet flange, wherein the inhalation cavity is located inside the main cavity, and the main cavity is connected with the exhalation cavity and the inhalation cavity; the exhalation cavity and the inhalation cavity are respectively provided with a movable exhalation cylinder and a movable inhalation cylinder; An exhalation pilot device is connected to the main cavity and the exhalation cavity; the exhalation pilot device has an exhalation pilot cavity that allows communication with the outside world, and an exhalation pilot piston is arranged in the exhalation pilot cavity; The suction pilot device is connected to the main cavity and the suction cavity; the suction pilot device has a suction pilot cavity that allows communication with the outside, and a suction pilot piston is arranged in the suction pilot cavity.

2. A breathing valve for overcoming back pressure according to claim 1, characterized in that: The surfaces of the exhalation cylinder and the inhalation cylinder are respectively provided with an exhalation sealing pad and an inhalation sealing pad, the exhalation cylinder cooperates with the inner wall of the exhalation cavity through the exhalation sealing pad, and the inhalation cylinder cooperates with the inhalation cavity through the inhalation sealing pad; The exhalation outlet flange is connected to the inner wall of the exhalation cavity that cooperates with the exhalation sealing pad, allowing the exhalation cylinder to open or completely close the exhalation outlet flange by moving along the inner wall of the exhalation cavity; the inlet flange is connected to the inner wall of the inhalation cavity that cooperates with the inhalation sealing pad, allowing the inhalation cylinder to open or completely close the inlet flange by moving along the inner wall of the inhalation cavity.

3. A breathing valve for overcoming back pressure according to claim 2, characterized in that: The exhalation cavity is connected to the main cavity via a first opening, and the first opening is located on the inner wall of the exhalation cavity which is not matched with the exhalation sealing pad; the inhalation cavity is provided with a second opening on the inner wall which is not matched with the inhalation sealing pad, and the inhalation cavity is provided with a third opening on the inner wall which is matched with the inhalation cylinder, and an inhalation spring is connected between the second opening and the inhalation cylinder.

4. A breathing valve for overcoming back pressure according to claim 3, characterized in that: An exhalation pilot piston is arranged in the exhalation pilot cavity, and the exhalation pilot piston includes a lower sealing pad of the exhalation pilot piston, an upper sealing pad of the exhalation pilot piston, and an exhalation pilot connecting rod connecting the lower sealing pad of the exhalation pilot piston and the upper sealing pad of the exhalation pilot piston; the lower sealing pad of the exhalation pilot piston and the upper sealing pad of the exhalation pilot piston are both matched with the inner wall of the exhalation pilot cavity, and the diameter of the lower sealing pad of the exhalation pilot piston is smaller than the diameter of the upper sealing pad of the exhalation pilot piston; the exhalation pilot cavity is provided with at least one exhalation air pressure balance hole connected to the outside.

5. A breathing valve for overcoming back pressure according to claim 4, characterized in that: The exhalation pilot cavity includes an exhalation pilot first cavity, an exhalation pilot second cavity, and an exhalation pilot third cavity which are connected in sequence. The exhalation pilot piston lower sealing pad, the exhalation pilot piston upper sealing pad, and the exhalation pilot connecting rod are respectively matched with the exhalation pilot first cavity, the exhalation pilot second cavity, and the exhalation pilot third cavity. The exhalation pilot first cavity is connected to the exhalation cavity through the first exhalation air pipe, and the exhalation pilot second cavity is connected to the main cavity through the second exhalation air pipe.

6. A breathing valve for overcoming back pressure according to claim 5, characterized in that: A suction pilot piston is arranged in the suction pilot cavity, and the suction pilot piston includes a lower sealing gasket of the suction pilot piston, an upper sealing gasket of the suction pilot piston, and a suction pilot connecting rod connecting the lower sealing gasket of the suction pilot piston and the upper sealing gasket of the suction pilot piston; the lower sealing gasket of the suction pilot piston and the upper sealing gasket of the suction pilot piston are both matched with the inner wall of the suction pilot cavity, and the diameter of the lower sealing gasket of the suction pilot piston is larger than the diameter of the upper sealing gasket of the suction pilot piston; the suction pilot cavity is provided with at least one suction air pressure balance hole connected to the outside.

7. A breathing valve for overcoming back pressure according to claim 6, characterized in that: The suction pilot cavity includes a suction pilot first cavity and a suction pilot second cavity which are connected in sequence. The suction pilot piston lower sealing gasket is matched with the suction pilot first cavity. The suction pilot piston upper sealing gasket and the suction pilot connecting rod are both matched with the suction pilot second cavity. The suction pilot first cavity is connected to the suction cavity and the main cavity through the first suction air pipe and the second suction air pipe respectively.

8. A breathing valve for overcoming back pressure according to claim 7, characterized in that: The exhalation pilot first cavity and the inhalation pilot first cavity are respectively provided with an exhalation air pressure balance hole and an inhalation air pressure balance hole.

9. A breathing valve for overcoming back pressure according to claim 8, characterized in that: The exhalation pilot connecting rod and the inhalation pilot connecting rod are respectively sleeved with an exhalation pilot spring and an inhalation pilot spring.

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