A pilot valve and respiratory system

Abstract

The present application relates to the technical field of pilot breathing valve, and particularly relates to a pilot valve and a breathing system, which comprises a valve body, an upper cavity, a middle cavity and a lower cavity are formed in the valve body by an inductive diaphragm and an amplification diaphragm, the middle cavity and the lower cavity are respectively communicated with a first gas channel and a second gas channel, the second gas channel is provided with a first flow-limiting airway, wherein a stress area of the inductive diaphragm is S1, a stress area of the amplification diaphragm is S2, and S2>S1. By adopting the 'dual-diaphragm differential design', the middle cavity only bears the function of providing stable downward resistance, and the area difference between the amplification diaphragm and the inductive diaphragm specially amplifies the influence of the lower cavity pressure change on the net upward force, which not only avoids the problem that the gas in the sealing cavity of the main valve is retained and the opening of the valve disc is hindered due to the high-frequency opening and closing of the pilot seat in the traditional structure, but also improves the pressure regulation stability by forming a clear and stable opening and return seat pressure difference interval.

Description

Technical Field

[0001] This invention relates to the field of pilot-operated breathing valve technology, and in particular to a pilot valve and breathing system. Background Technology

[0002] As the core device for overpressure protection in various storage tank systems, the pilot-operated breather valve can automatically vent or draw in air based on changes in pressure inside and outside the storage tank, ensuring the safety of the storage tank.

[0003] Cryogenic storage tanks are mainly used to store cryogenic media such as liquid nitrogen, liquid oxygen, liquid argon and LNG. Cryogenic liquids are extremely prone to vaporization, and in order to maintain a slightly positive pressure environment inside the tank, pressure fluctuations inside the tank must be strictly controlled.

[0004] Pilot-operated breather valves offer significantly better sealing than conventional breather valves, minimizing the entry of external heat, preventing excessive evaporation of the medium, and ensuring system stability. In cryogenic environments, the mechanical components of traditional breather valves are prone to jamming due to freezing points or material contraction. Pilot-operated breather valves, however, are designed and use advanced materials to effectively prevent freezing and adhesion, ensuring reliable operation of safety devices in critical moments.

[0005] Traditional pilot-operated breather valves generally rely on a single diaphragm structure to establish a balance between pressure and force: the diaphragm only bears the pressure inside the tank on one side, and the other side bears the downward resistance such as the spring preload. When the thrust generated by the pressure inside the tank exceeds the resistance, the breather valve opens to release gas, and vice versa.

[0006] However, this single-diaphragm structure has significant drawbacks. Because pressure and force are transmitted solely through a single diaphragm, it lacks the amplification effect for pressure changes, and there is typically no significant and stable pressure differential design between the middle and lower chambers. When the pressure inside the tank fluctuates slightly, the net force on the single diaphragm easily switches frequently between "pushing the valve to open" and "blocking the valve from opening," leading to high-frequency opening and closing (fluttering) of the pilot-operated breather valve. On the one hand, high-frequency opening and closing accelerates the wear of components such as the valve seat and diaphragm, reducing the lifespan of the breather valve; on the other hand, frequent opening and closing prevents the breather valve from stably and effectively completing the venting action, making it difficult to effectively control the tank pressure, posing a safety hazard of tank overpressure, and seriously affecting the operational safety and stability of the storage tank. Therefore, improvements are needed. Summary of the Invention

[0007] In this section, as well as in the abstract and title of this application, some simplifications or omissions may be made to avoid obscuring the purpose of this section, the abstract, and the title of this application, and such simplifications or omissions shall not be used to limit the scope of the invention.

[0008] To address the problem that the single-diaphragm structure in the prior art easily leads to high-frequency opening and closing (chatter) of the pilot valve, one objective of the present invention is to provide a pilot valve.

[0009] To achieve the above objectives, the present invention adopts the following technical solution: a pilot valve, comprising a valve body, wherein an upper cavity, a middle cavity, and a lower cavity are formed inside the valve body by means of a sensing diaphragm and a magnifying diaphragm, the middle cavity and the lower cavity are respectively connected to a first gas channel and a second gas channel, the second gas channel being provided with a first flow-limiting gas passage; wherein, the force-bearing area of ​​the sensing diaphragm is S1, the force-bearing area of ​​the magnifying diaphragm is S2, and S2>S1.

[0010] In a preferred embodiment of the pilot valve of the present invention, the valve body further includes a pilot assembly, which includes a pilot spring and a pilot seat; the fixed end of the pilot spring is connected to the inner wall of the valve body and is located in the upper cavity; the pilot seat is connected to the telescopic end of the pilot spring, and the sensing diaphragm and the amplifying diaphragm are coaxially connected to the pilot seat.

[0011] In a preferred embodiment of the pilot valve of the present invention, the pilot assembly further includes an upper support, a lower support, and a connector; the upper support is connected to the pilot seat and is fitted to the upper end face of the sensing diaphragm; the lower support is connected to the pilot seat and is fitted to the upper end face of the amplifying diaphragm; the connector is connected to the pilot seat and is located between the sensing diaphragm and the lower support; wherein the height of the connector is equal to the height between the sensing diaphragm and the lower support.

[0012] In a preferred embodiment of the pilot valve of the present invention, the valve body further includes a vent, an exhaust pipe, a canister pressure air passage, and an atmospheric air passage; the vent is located at the lower end of the valve body and is in contact with the lower end face of the pilot seat; the exhaust pipe communicates with the valve body and is located above the vent; the canister pressure air passage is connected to the vent; and the atmospheric air passage is connected to the upper cavity.

[0013] As a preferred embodiment of the pilot valve of the present invention, the first gas channel includes a central cavity gas passage communicating with the central cavity and the vent hole, and a second flow-limiting gas passage is provided at the end of the central cavity gas passage facing the vent hole.

[0014] In a preferred embodiment of the pilot valve of the present invention, the second gas passage further includes a lower chamber gas passage connected to the tank pressure gas passage, and the first flow-limiting gas passage is connected between the tank pressure gas passage and the middle chamber gas passage.

[0015] In a preferred embodiment of the pilot valve of the present invention, the valve body further includes a flow-limiting needle connected to a first flow-limiting air passage, and the flow-limiting needle is threadedly connected to the valve body.

[0016] In order to solve the problem in the prior art that the high-frequency opening and closing of the pilot valve causes gas to stagnate in the sealing cavity of the main valve and hinders the normal opening of the valve disc opening and closing parts, another objective of the present invention is to provide a breathing system.

[0017] To achieve the above objectives, the present invention adopts the following technical solution: a breathing system, including a pilot valve, a main valve, and a tank pressure chamber connected to a storage tank. The tank pressure chamber is connected to a tank pressure air passage through a tank pressure pipeline, and the main valve is connected to a vent through a connecting channel.

[0018] In a preferred embodiment of the respiratory system of the present invention, the main valve further includes a sealed cavity formed by a partition diaphragm and communicating with the connecting channel, wherein the partition diaphragm is provided with a valve disc opening and closing element that contacts and connects with the top of the pressure chamber.

[0019] The beneficial effects of this invention are as follows: The "dual-diaphragm differentiated design" allows the middle cavity to only provide stable downward resistance, while the area difference between the amplifying diaphragm and the sensing diaphragm specifically amplifies the impact of pressure changes in the lower cavity on the net upward force. This avoids the problem of gas stagnation in the main valve sealing cavity caused by high-frequency opening and closing of the pilot seat in traditional structures, which hinders the opening of the valve disc. Furthermore, by forming a clear and stable pressure difference range between opening and reseating, the stability of pressure regulation is improved. Simultaneously, the stable opening and closing state reduces component wear, extends equipment lifespan, and lowers maintenance costs. It can also adapt to complex pressure fluctuation conditions, effectively compensating for the performance shortcomings of traditional single-diaphragm breather valves. Attached Figure Description

[0020] To more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings used in the following description of the embodiments will be briefly introduced. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0021] Figure 1 This is a schematic diagram of the structure of the sensing diaphragm and the magnifying diaphragm of the present invention.

[0022] Figure 2 This is a planar sectional view of the valve body of the present invention.

[0023] Figure 3 This is a three-dimensional sectional view of the valve body of the present invention.

[0024] Figure 4 This is a schematic diagram of the structure of the pilot component of the present invention.

[0025] Figure 5 For the present invention Figure 2 Enlarged diagram of point A in the middle.

[0026] Figure 6 For the present invention Figure 3 Enlarged diagram of point B in the middle.

[0027] Figure 7 This is a schematic diagram of the first flow-limiting airway of the present invention.

[0028] Figure 8 This is a planar sectional view of the main valve and tank body of the present invention.

[0029] Figure 9 This is a schematic diagram of the overall structure of the present invention.

[0030] In the diagram: 100, valve body; 101, sensing diaphragm; 102, magnifying diaphragm; C0, upper chamber; C1, middle chamber; C2, lower chamber; 103, first gas passage; 104, second gas passage; 104a, first flow-limiting gas passage; 105, pilot assembly; 105a, pilot spring; 105b, pilot seat; 105c, upper support; 105d, lower support; 105e, connecting piece; 106 107. Vent hole; 108. Exhaust pipe; 109. Tank pressure air passage; 110. Atmospheric air passage; 103a. Isolation diaphragm; 103b. Second flow-limiting air passage; 104b. Lower flow-limiting air passage; 111. Flow-limiting needle; 200. Main valve; 201. Tank pressure chamber; 202. Tank pressure pipe; 203. Connecting channel; 204. Separating diaphragm; 205. Sealing chamber; 206. Valve disc opening and closing element. Detailed Implementation

[0031] To enable those skilled in the art to better understand the present invention, the present invention will be further described in detail below with reference to specific embodiments and accompanying drawings.

[0032] The terminology used in this invention is that which is currently widely used in the art in consideration of the function of the invention; however, these terms may vary according to the intent of those skilled in the art, precedent, or new technology in the art. Furthermore, specific terms may be chosen by the applicant, and in such cases, their detailed meanings will be described in the detailed description of the invention. Therefore, the terms used in this specification should not be construed as simple names, but rather based on their meanings and the overall description of the invention.

[0033] Reference Figures 1-3 This embodiment provides a pilot valve, including a valve body 100. Inside the valve body 100, an upper cavity C0, a middle cavity C1, and a lower cavity C2 are formed by a sensing diaphragm 101 and a magnifying diaphragm 102. The middle cavity C1 and the lower cavity C2 are respectively connected to a first gas channel 103 and a second gas channel 104. The second gas channel 104 is provided with a first flow-limiting gas channel 104a. The force-bearing area of ​​the sensing diaphragm 101 is S1, the force-bearing area of ​​the magnifying diaphragm 102 is S2, and S2>S1.

[0034] Furthermore, the valve body 100 also includes a pilot assembly 105, which includes a pilot spring 105a and a pilot seat 105b; the pilot spring 105a has its fixed end connected to the inner wall of the valve body 100 and located in the upper cavity C0; the pilot seat 105b is connected to the telescopic end of the pilot spring 105a, and the sensing diaphragm 101 and the amplifying diaphragm 102 are coaxially connected to the pilot seat 105b.

[0035] Furthermore, the valve body 100 also includes a vent 106, an exhaust pipe 107, a tank pressure air passage 108, and an atmospheric pipe 109; the vent 106 is located at the lower end of the valve body 100 and is in contact with the lower end face of the pilot seat 105b; the exhaust pipe 107 is connected to the valve body 100 and is located above the vent 106; the tank pressure air passage 108 is connected to the vent 106; and the atmospheric pipe 109 is connected to the upper cavity C0.

[0036] The lower end face of the pilot spring 105a abuts against the upper end face of the pilot seat 105b. The sensing diaphragm 101 and the amplifying diaphragm 102 are sleeved on the outer periphery of the pilot seat 105b, and the sensing diaphragm 101 and the amplifying diaphragm 102 are coaxially arranged with the pilot seat 105b. The opening and closing of the vent 106 are controlled by the axial movement of the pilot seat 105b.

[0037] Specifically, by simultaneously arranging a sensing diaphragm 101 and an amplifying diaphragm 102 inside the valve body 100, and ensuring a difference in the force-bearing areas between the sensing diaphragm 101 and the amplifying diaphragm 102, this "dual-diaphragm differential design" (S2>S1) utilizes the area difference between the amplifying diaphragm 102 and the sensing diaphragm 101 to amplify the influence of pressure changes in the lower chamber C2 of the amplifying diaphragm 102 on the net upward force. When the pressure in the tank pressure chamber 201 (i.e., inside the storage tank) reaches the opening value, the thrust generated by the pressure in the lower chamber C2 through the amplifying diaphragm 102 and the resistance generated by the pressure in the middle chamber C1 through the sensing diaphragm 101 form a stable force balance difference, ensuring that once the pilot seat 105b is opened, it can maintain a stable open state, avoiding high-frequency opening and closing.

[0038] This design allows the gas in the sealing cavity 205 to be released smoothly without any stagnation or accumulation, completely eliminating the problem of "obstructing the opening of the valve disc opening and closing element 206", ensuring that the main valve 200 can be opened quickly and completely when needed, and efficiently complete the exhaust.

[0039] Reference Figure 4This embodiment provides a pilot valve, in which the pilot assembly 105 further includes an upper support 105c, a lower support 105d, and a connector 105e; the upper support 105c is connected to the pilot seat 105b and is attached to the upper end face of the sensing diaphragm 101; the lower support 105d is connected to the pilot seat 105b and is attached to the upper end face of the amplifying diaphragm 102; the connector 105e is connected to the pilot seat 105b and is located between the sensing diaphragm 101 and the lower support 105d; wherein, the height of the connector 105e is equal to the height between the sensing diaphragm 101 and the lower support 105d.

[0040] The upper support 105c, the lower support 105d, and the connector 105e are fixedly connected to the outer periphery of the pilot seat 105b and are coaxially arranged with the pilot seat 105b. By setting the height of the connector 105e to be consistent with the gap height between the sensing diaphragm 101 and the lower support 105d, the sensing diaphragm 101 and the amplifying diaphragm 102 can be kept to rise or fall synchronously when the pilot seat 105b moves axially. Both the sensing diaphragm 101 and the amplifying diaphragm 102 are made of a material with a certain elastic space.

[0041] Furthermore, the valve body 100 also includes a partition diaphragm 110 connected to the pilot seat 105b and located below the amplifying diaphragm 102, with the partition diaphragm 110 communicating with the atmosphere through an exhaust pipe 107 below it.

[0042] like Figure 5 As shown, the isolation diaphragm 110 is fixedly connected inside the valve body 100 and is located below the amplifying diaphragm 102. The space between the isolation diaphragm 110 and the amplifying diaphragm 102 is the lower cavity C2. The lower part of the isolation diaphragm 110 is connected to the atmosphere through the exhaust pipe 107.

[0043] Reference Figures 5-7 This embodiment provides a pilot valve, including a first gas passage 103 including a central cavity air passage 103a communicating with a central cavity C1 and a vent hole 106, and a second flow-limiting air passage 103b provided at one end of the central cavity air passage 103a facing the vent hole 106.

[0044] Furthermore, the second gas passage 104 also includes a lower cavity gas passage 104b connected to the canister pressure gas passage 108, and a first flow-limiting gas passage 104a connected between the canister pressure gas passage 108 and the middle cavity gas passage 103a.

[0045] Furthermore, the valve body 100 also includes a flow-limiting needle 111 connected to the first flow-limiting air passage 104a, and the flow-limiting needle 111 is threadedly connected to the valve body 100.

[0046] In this process, the position of the flow-limiting needle 111 is adjusted by tightening the screw, thereby adjusting the width of the first flow-limiting air passage 104a. In turn, the pressure difference between the lower chamber C2 and the middle chamber C1 is adjusted to regulate the reseating pressure of the pilot seat 105b.

[0047] Reference Figures 8-9 This embodiment provides a breathing system, including a pilot valve and a main valve 200, including a tank pressure chamber 201 connected to a storage tank. The tank pressure chamber 201 is connected to a tank pressure air passage 108 through a tank pressure pipe 202, and the main valve 200 is connected to a vent 106 through a connecting channel 203.

[0048] The tank pressure chamber 201 is used to connect to the storage tank, and the pressure in the tank pressure chamber 201 is always equal to the pressure in the storage tank. One end of the tank pressure pipe 202 is connected to the tank pressure air passage 108, and the other end is connected to the tank pressure chamber 201.

[0049] Preferably, the other end of the tank pressure pipeline 202 can also be directly connected to the storage tank.

[0050] Furthermore, the main valve 200 also includes a sealed cavity 205 formed by a partition diaphragm 204 that communicates with the connecting channel 203, and a valve disc opening and closing element 206 that is in contact with the top of the tank pressure cavity 201 is provided on the partition diaphragm 204.

[0051] When the pilot seat 105b is opened, the gas in the sealing chamber 205 is fully released, causing the valve disc opening and closing element 206 to be pushed open and separated from the pressure chamber 201, thus realizing the exhalation of the main valve 200.

[0052] Existing pilot-operated breather valves typically employ a single diaphragm structure to establish a balance between pressure and force (i.e., only the sensing diaphragm 101 is used). The sensing diaphragm 101 needs to withstand both the pressure of the canister chamber 201 (lower chamber C2 pressure) and the downward resistance such as the spring preload. When the thrust generated by the pressure of the canister chamber 201 exceeds the resistance, the main valve 200 opens to exhaust air, and vice versa.

[0053] However, this single-diaphragm structure transmits pressure and force through only a single diaphragm, lacking the amplification effect of pressure changes. When the pressure in the tank chamber 201 fluctuates slightly, the force on the single diaphragm is prone to frequently switching between "push valve opening" and "block valve opening", causing the pilot-operated breather valve to exhibit high-frequency opening and closing (fluttering) phenomenon.

[0054] Specifically, when the valve body 100 is equipped with only a sensing diaphragm 101 (i.e., a single diaphragm), the sensing diaphragm 101 can only form two chambers inside the valve body 100, namely the upper chamber C0 and the lower chamber C2. The upper chamber C0 is connected to the atmosphere, and the lower chamber C2 is connected to the pressure chamber 201.

[0055] The pressure on the upper surface of the sensing diaphragm 101 (i.e., the pressure of the upper cavity C0) is set to atmospheric pressure, which is always atmospheric pressure because it is connected to the atmosphere; the pressure on the lower surface of the sensing diaphragm 101 before the pilot seat 105b is opened (i.e., the pressure of the lower cavity C2) is set to the same pressure as the pressure chamber 201 because it is connected to the pressure chamber 201; the pressure on the lower surface of the sensing diaphragm 101 after the pilot seat 105b is opened (i.e., the pressure of the lower cavity C2) is set to be slightly lower than the pressure of the pressure chamber 201; S1 is set to the effective force-bearing area of ​​the sensing diaphragm 101; the total downward resistance of the pilot assembly 105 is set to G+F, where G is the weight of the pilot assembly 105 and F is the spring preload.

[0056] However, when the valve body 100 is equipped with only a sensing diaphragm 101 (i.e., a single diaphragm), the opening and closing of the pilot seat 105b depends entirely on the balance between the "total upward pressure generated by the pressure difference between the upper and lower sides of the sensing diaphragm 101" and the "total downward resistance (G+F)".

[0057] Total upward pressure of a single diaphragm: the difference between the pressure on the lower surface of the sensing diaphragm 101 and the atmospheric pressure on the upper surface, multiplied by the area of ​​the diaphragm subjected to force.

[0058] ,

[0059] in, The pressure on the lower surface of the sensing diaphragm 101 before it is turned on is After opening, it is .

[0060] Balance condition: When the total upward pressure is greater than or equal to the total downward resistance, the pilot seat 105b opens; otherwise, it closes.

[0061] Pilot 105b activation threshold formula: .

[0062] The fallback threshold formula for pilot seat 105b is as follows: .

[0063] Threshold formula activated by pilot seat 105b From this, we can deduce the pressure that the pressure chamber 201 needs to reach when the pilot seat 105b is opened:

[0064] .

[0065] because (Atmospheric pressure), G+F (total downward resistance) (The effective force-bearing area of ​​the sensing diaphragm 101) are all fixed values. It is a unique and fixed threshold for enabling.

[0066] When it returns to its seat, the pressure in the pressure chamber 201 only needs to drop to a certain level. < That will satisfy Therefore, the difference between the opening pressure of the pilot seat 105b and the repositioning pressure of the pilot seat 105b (i.e., the "pressure difference range") is:

[0067] .

[0068] The following are specific examples for verification: For example, taking atmospheric pressure. (That is, calculated according to gauge pressure), if G + F = 120N, ,but:

[0069] .

[0070] After exhaust Only needs to be reduced to 149 kPa ), which can satisfy Pilot seat 105b immediately closes.

[0071] Because the pressure difference range is too small, even slight fluctuations in the pressure of the tank chamber 201 can easily exceed the opening and closing threshold (such as pressure fluctuations during loading and unloading, or pressure changes caused by changes in ambient temperature).

[0072] In actual operating conditions, the pressure in tank pressure chamber 201 (storage tank) is... It has consistently remained in a state of "small fluctuations," combined with the aforementioned extremely small pressure difference range. The high-frequency start-stop process can be derived using formulas. When When the pressure in the pressure chamber 201 reaches 150 kPa:

[0073] .

[0074] The pilot seat 105b opens, and the sealed cavity 205 begins to exhaust air.

[0075] At the moment of exhaust, the pressure of C2 in the lower chamber The pressure in the pressure chamber 201 of the can decreases synchronously. =149 kPa, at this time:

[0076] .

[0077] The pilot seat 105b loses its opening power and closes quickly, preventing the sealed chamber 205 from venting.

[0078] After the tank is closed, the pressure chamber 201 continues to produce gas or feed material. The pressure quickly rises back to 150 kPa, and the pilot seat 105b opens again. This process repeats, forming a high-frequency cycle of "opening → closing → opening → closing," which is the "high-frequency opening and closing (chatter)" phenomenon of the pilot seat 105b mentioned above. This can lead to gas retention in the sealing cavity 205 of the main valve 200, hindering the opening of the valve disc opening and closing parts 206.

[0079] When a sensing diaphragm 101 and an amplifying diaphragm 102 are provided inside the valve body 100, and (when S2>S1), the sensing diaphragm 101 and the amplifying diaphragm 102 will form an upper cavity C0, a middle cavity C1 and a lower cavity C2 inside the valve body 100.

[0080] set up The pressure on the upper surface of the sensing diaphragm 101 (i.e., the pressure of the upper cavity C0) is always atmospheric pressure because it is connected to the atmosphere.

[0081] set up Before the pilot seat 105b is opened, the pressure in the middle cavity C1 is equal to the pressure in the tank pressure cavity 201. = ).

[0082] set up After the pilot seat 105b is opened, the pressure in the middle cavity C1 is higher than atmospheric pressure but much lower than the pressure in the tank pressure cavity 201, i.e. < < ).

[0083] set up Before the pilot seat 105b is opened, the pressure in the lower chamber C2 is equal to the pressure in the tank pressure chamber 201. = ).

[0084] set up The pressure in the lower chamber C2 after the pilot seat 105b is opened is slightly lower than the pressure in the tank pressure chamber 201. < ).

[0085] S1 is set as the effective force-bearing area of ​​the sensing diaphragm 101, and S2 is set as the effective force-bearing area of ​​the amplifying diaphragm 102, with S2 > S1.

[0086] The total downward resistance of the pilot assembly 105 is set to G+F (where G is the weight of the pilot assembly 105 and F is the spring preload).

[0087] The opening and closing of the dual-diaphragm pilot valve depends on the balance between the "resultant force of the sensing diaphragm 101 and the amplifying diaphragm 102" and the "total downward resistance (G+F)," combined with the "pressure difference between the middle cavity C1 and the lower cavity C2 on the combined effect of the sensing diaphragm 101 and the amplifying diaphragm 102."

[0088] The total net upward pressure consists of two parts: first, the upward thrust generated by the pressure difference between the lower cavity C2 and the middle cavity C1 on the amplifying diaphragm 102; and second, the upward thrust generated by the pressure difference between the middle cavity C1 and the upper cavity C0 on the sensing diaphragm 101.

[0089] .

[0090] Since P2 = P1, the simplified result before enabling is:

[0091] .

[0092] Equilibrium condition: When the total net upward force is greater than or equal to the total downward resistance, the pilot seat 105b opens; otherwise, it closes. The specific threshold is: Pilot seat 105b opening threshold formula: .

[0093] Before the pilot seat 105b is opened, P1 = P2.

[0094] The fallback threshold formula for pilot seat 105b is as follows: .

[0095] After the pilot seat 105b is opened, .

[0096] Threshold formula activated by pilot seat 105b From this, we can deduce the pressure that the pressure chamber 201 needs to reach when the pilot seat 105b is opened:

[0097] .

[0098] After the pilot seat 105b is opened, the pressure in the middle cavity C1 drops to ( < < ), lower chamber C2 pressure Because it is directly connected to the pressure chamber 201, the descent is relatively small. < = At this time, the pressure difference acting on the amplifying diaphragm 102 This will generate a significant additional upward force.

[0099] It is this additional force (whose magnitude is the difference in area) (Proportional to) the pilot seat 105b, so that it is under pressure in the pressure chamber 201. Below the opening pressure to a certain extent It can remain open even when [the device is not in use].

[0100] Therefore, by properly designing the values ​​of S2 and S1, a wide difference (pressure difference range) can be created between the opening pressure and the falling pressure of the pilot seat 105b.

[0101] .

[0102] The following are specific examples for verification: For example, taking atmospheric pressure. (i.e., calculated according to gauge pressure), if .

[0103] The opening of the pilot seat 105b is determined by the force balance of the sensing diaphragm 101, and its opening threshold pressure is:

[0104] .

[0105] When the pressure in the pressure chamber 201 reaches 150 kPa, the pilot seat 105b opens.

[0106] After the pilot seat 105b is opened, the gas flow causes the pressure in the middle cavity C1 to increase. Decline. Assuming stability at... =20kPa, while the pressure P2′ in the lower chamber C2 is directly connected to the pressure chamber 201, assuming it drops to... =100kPa.

[0107] At this point, the total net upward force is:

[0108]

[0109] When the total net upward force is greater than the total downward resistance:

[0110] .

[0111] The pilot seat 105b will remain open, even though the pressure in the pressure chamber 201 (100 kPa) is below the opening threshold (150 kPa). The above clearly demonstrates the pressure difference range generated by the dual diaphragm structure.

[0112] Pilot seat 105b will fall back: Pilot seat 105b will only fall back when the pressure in the pressure chamber 201 further decreases, making the net upward force less than the total downward resistance. For example, when Dropped to 80 Time (assuming) The corresponding decrease is approximately 16 ):

[0113]

[0114] At this point, the pilot seat 105b begins to close. Therefore, the actual reseating pressure is approximately 80 kPa, creating a wide pressure differential of about 70 kPa between it and the opening pressure (150 kPa). (≈70 kPa), this pressure difference range is much larger than the typical working pressure fluctuation of the tank pressure chamber 201 (e.g., ±5 kPa). Therefore, when loading / unloading or temperature changes cause small fluctuations in the tank pressure chamber 201, the fluctuation amplitude cannot cross this wide opening and closing threshold range, thus fundamentally avoiding frequent operation (chatter) of the pilot seat 105b.

[0115] so > The structure utilizes the pressure difference between the middle cavity C1 and the lower cavity C2 generated by the flow resistance after the pilot seat 105b is opened to generate an additional holding force in the area difference region, thus achieving a wide pressure difference range and providing the system with excellent anti-interference stability.

[0116] Derivation of the pilot seat 105b's pullback pressure ratio (k value): The pullback of the pilot seat 105b is determined by the force balance state after opening. The critical condition for pullback is that the net upward force equals the total downward resistance (G+F). The force balance equation is as follows:

[0117] .

[0118] At the instant the pilot seat 105b opens, the pressure in the pressure chamber 201 is the opening pressure P, and the opening condition is met:

[0119] .

[0120] Substituting formula (2) into formula (1) eliminates (G+F), yielding the relationship between the pressures at the critical fallout state:

[0121] .

[0122] After simplification, we get:

[0123] .

[0124] Define the pullback pressure ratio k = That is, the pressure in the can pressure chamber 201 when it reseated. The ratio of the opening pressure P to the opening pressure.

[0125] Since the pressure in the lower chamber C2 is nearly equal to that in the pressure chamber 201, This is the pressure in the can pressure chamber 201 during reseating. Simultaneously, the pressure in the middle chamber... It is determined by the flow rate and flow resistance through the first flow-limiting airway 104a and the second flow-limiting airway 103b.

[0126] Reference Figure 3 , Figure 5 , Figure 6 The gas in the canister pressure channel 108 enters the valve body 100 in two separate paths.

[0127] Route A: via the inferior vena cava C2 ​​airway → inferior vena cava C2.

[0128] Route B: Through the first flow-limiting airway 104a → the middle cavity C1 airway → the middle cavity C1.

[0129] Similarly, when the pilot seat 105b is opened, the gas in the middle cavity C1 and the lower cavity C2 is discharged from the valve body 100 in two separate paths.

[0130] Route A: Through the lower cavity C2 airway → first flow-limiting airway 104a → second flow-limiting airway 103b → exhaust pipe 107.

[0131] Route B: Through the C1 airway in the middle cavity → the second flow-limiting airway 103b → the exhaust pipe 107.

[0132] When the pilot seat 105b is opened, observe the flow path of gas through the pilot valve in the pressure chamber 201. There are two sections with a diameter significantly smaller than the others, such as... Figure 5 As shown, the first flow-limiting airway 104a and the second flow-limiting airway 103b are significantly smaller than the airflow channels such as the tank pressure airway 108 and the vent 106.

[0133] According to fluid mechanics, under steady flow conditions, the mass flow rate through a series of channels is equal. It is assumed that the flow resistance is mainly determined by the geometry of the two flow-limiting channels and follows the law reflected by the Darcy-Weisbach formula, i.e., the flow resistance is related to... If they are directly proportional, then:

[0134] ,

[0135] in: , is the pressure drop generated when the air flows through the first flow-limiting airway 104a.

[0136] , which is the pressure drop generated by the flow through the second flow-limiting airway 103b.

[0137] because At atmospheric pressure, it can be used in engineering estimations. Therefore, the pressure drop of the second flow-limiting airway 103b can be approximated as Δp2≈ 0. .

[0138] L1: Length of the first flow-limiting airway 104a, L2: Length of the second flow-limiting airway 103b.

[0139] d1: Diameter of the first flow-limiting airway 104a; d2: Diameter of the second flow-limiting airway 103b.

[0140] By combining equations (3) and (4), the relationship between the fallback pressure ratio k and the diaphragm areas S1 and S2, as well as the flow channel geometry L1, L2, d1, and d2, can be established. By designing these parameters, a specific fallback pressure ratio can be achieved.

[0141] Specific data examples are provided for illustration: If the design target is k=0.93, and S2=1.5×S1 is selected, that is, S2 / S1=1.5, substituting into equation (3):

[0142] .

[0143] Will =k = Substitute:

[0144] .

[0145] Solving for:

[0146] .

[0147] Then = and = Substitute into the flow resistance relationship (4):

[0148] .

[0149] Therefore, to achieve a reseating pressure ratio of 93%, the flow channel dimensions must meet the following requirements:

[0150] .

[0151] This requirement can be met by freely combining the diameter ratio (d1:d2) and the length ratio (L1:L2).

[0152] For example, if we set d1:d2 = 5:3, then L1:L2≈ ≈1.3.

[0153] In summary, the drop pressure ratio (k value) of the pilot seat 105b is not determined by a single factor, but rather by the diaphragm area ratio (S2 / S1) and the flow resistance ratio of the flow-limiting airway. ) / ( The result of their combined action. By adjusting these design parameters, the opening and closing pressure difference range of the pilot seat 105b can be precisely controlled, thereby avoiding chatter.

[0154] Finally, it should be noted that the methods and devices described in detail above are merely embodiments, and those skilled in the art can modify these embodiments in different ways as long as they do not depart from the scope of the present invention.

Claims

1. A pilot valve, characterized in that: include, The valve body (100) has an upper cavity (C0), a middle cavity (C1) and a lower cavity (C2) formed inside the valve body (100) by a sensing diaphragm (101) and a magnifying diaphragm (102). The middle cavity (C1) and the lower cavity (C2) are respectively connected to a first gas channel (103) and a second gas channel (104). The second gas channel (104) is provided with a first flow-limiting gas channel (104a). Wherein, the force-bearing area of ​​the sensing diaphragm (101) is S1, the force-bearing area of ​​the amplifying diaphragm (102) is S2, and S2>S1; The valve body (100) also includes a pilot assembly (105), which includes a pilot spring (105a) and a pilot seat (105b). The pilot spring (105a) has its fixed end connected to the inner wall of the valve body (100) and located in the upper cavity (C0); The pilot seat (105b) is connected to the telescopic end of the pilot spring (105a), and the sensing diaphragm (101) and the amplifying diaphragm (102) are coaxially connected to the pilot seat (105b). The valve body (100) also includes a vent (106), an exhaust pipe (107), a tank pressure duct (108), and an atmospheric duct (109). The vent (106) is located at the lower end of the valve body (100) and is in contact with the lower end face of the pilot seat (105b). The exhaust pipe (107) is connected to the valve body (100) and is located above the vent (106); The canister pressure air passage (108) is connected to the vent (106); The atmospheric conduit (109) is connected to the upper cavity (C0); The valve body (100) also includes a partition diaphragm (110) connected to the pilot seat (105b) and located below the amplifying diaphragm (102), the partition diaphragm (110) being connected to the atmosphere via an exhaust pipe (107); The first gas passage (103) includes a central cavity airway (103a) communicating with the central cavity (C1) and the vent (106), and a second flow-limiting airway (103b) is provided at one end of the central cavity airway (103a) facing the vent (106). The second gas passage (104) also includes a lower cavity gas passage (104b) connected to the canister pressure gas passage (108), and the first flow-limiting gas passage (104a) is connected between the canister pressure gas passage (108) and the middle cavity gas passage (103a).

2. The pilot valve as described in claim 1, characterized in that: The pilot assembly (105) also includes an upper support (105c), a lower support (105d), and a connector (105e). The upper support (105c) is connected to the pilot seat (105b) and is attached to the upper end face of the sensing diaphragm (101). The lower support (105d) is connected to the pilot seat (105b) and is attached to the upper surface of the magnifying diaphragm (102); The connector (105e) is connected to the pilot seat (105b) and is located between the sensing diaphragm (101) and the lower support (105d); The height of the connector (105e) is equal to the height between the sensing diaphragm (101) and the lower support (105d).

3. The pilot valve as described in claim 1 or 2, characterized in that: The valve body (100) also includes a flow-limiting needle (111) connected to the first flow-limiting air passage (104a), and the flow-limiting needle (111) is threadedly connected to the valve body (100).

4. A respiratory system, characterized in that: The system includes the pilot valve as described in claim 1 or 2, and also includes a main valve (200) and a tank pressure chamber (201) connected to the storage tank. The tank pressure chamber (201) is connected to the tank pressure air passage (108) through a tank pressure pipe (202), and the main valve (200) is connected to the vent (106) through a connecting channel (203).

5. The respiratory system as described in claim 4, characterized in that: The main valve (200) also includes a sealed cavity (205) formed by a partition diaphragm (204) and communicating with the connecting channel (203). The partition diaphragm (204) is provided with a valve disc opening and closing element (206) that is in contact with the top of the pressure chamber (201).

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