Combined sealing structure for piston dynamic seal of high-pressure hydrogen pressure reducing valve

Abstract

The invention relates to the field of pressure reducing valves, and discloses a combined type sealing structure for piston dynamic sealing of a high-pressure hydrogen pressure reducing valve, which comprises a valve body provided with a valve cavity and a piston piece arranged in the valve cavity in a sliding manner, the valve cavity comprises an upper valve cavity, a sliding part and a lower valve cavity from top to bottom, and the upper valve cavity is communicated with the lower valve cavity through the sliding part; the upper piston piece comprises a head end arranged in the upper valve cavity in a sliding mode and a sliding section in sliding fit with the sliding portion, the upper piston piece further comprises a spring arranged on the sliding section in a sleeving mode, the diameter of the head end is larger than that of the sliding section, the piston piece slides in a reciprocating mode to adjust opening and closing of the air inlet, and the head end divides the upper valve cavity into a first cavity and a second cavity communicated with the atmosphere. An air guide part communicated with the first cavity and the lower valve cavity is formed in the piston piece, Y-shaped sealing rings and O-shaped sealing rings are arranged on the periphery of the head end and the periphery of the sliding section in a sleeving mode, and the Y-shaped sealing rings are arranged at the top end of the head end and the tail end of the sliding section respectively, so that the pressure reducing valve structure is good in sealing effect.

Description

Technical Field

[0001] The invention relates to the field of pressure reducing valves, and in particular to a combined sealing structure for dynamic sealing of a piston of a high-pressure hydrogen pressure reducing valve. Background Art

[0002] Pressure reducing valves (also known as pressure stabilizing valves) are widely used in various gas supply pipelines. Generally, the flow of gas is adjusted by controlling the opening of the opening and closing parts in the valve body, thereby adjusting the higher inlet pressure to the lower outlet pressure, and keeping the outlet pressure stable within a certain range. In pipelines with large pressure differences, for example, the hydrogen supply pipeline of a fuel cell, in order to maintain the vehicle's cruising range, hydrogen usually needs to be stored in the form of high pressure. However, for a hydrogen fuel cell stack, normal operating conditions require a lower air pressure, and the hydrogen needs to be decompressed during the process of flowing from the storage tank through the fuel cell. In the prior art, piston-type pressure reducing valves are more common in the field of hydrogen energy, but the dynamic sealing effect on the piston body is often poor. For hydrogen with the smallest molecules, this sealing method may cause hydrogen to leak into the environment, especially when applied to fuel cells, it may bring dangers in use. A pressure reducing valve structure with good sealing effect should be provided. Summary of the invention

[0003] The present invention is intended to provide a combined sealing structure for dynamic sealing of a piston of a high-pressure hydrogen pressure reducing valve, so as to provide a pressure reducing valve structure with good sealing effect.

[0004] To achieve the above-mentioned purpose, the present invention adopts the following technical scheme: a combined sealing structure for the dynamic seal of the piston of a high-pressure hydrogen pressure reducing valve, comprising a valve body provided with a valve cavity and a piston member slidably arranged in the valve cavity, the valve cavity comprising an upper valve cavity, a sliding portion and a lower valve cavity from top to bottom, the upper valve cavity and the lower valve cavity are connected through the sliding portion, a gas transmission joint is arranged at the top of the upper valve cavity, a valve seat is also arranged below the valve body, and an air inlet hole is opened on the valve seat; the piston member comprises a head end slidably arranged in the upper valve cavity and a sliding section slidably matched with the sliding portion, and also comprises a spring sleeved on the sliding section, the diameter of the head end is larger than that of the sliding section, the piston member reciprocates to adjust the opening and closing of the air inlet hole, the head end divides the upper valve cavity into a first cavity and a second cavity connected to the atmosphere, an air guide portion connecting the first cavity and the lower valve cavity is opened in the piston member, a Y-type sealing ring and an O-type sealing ring are sleeved on the outer periphery of the head end and the sliding section, and the Y-type sealing ring is respectively arranged at the top of the head section and the tail of the sliding section.

[0005] The beneficial effects of this program are:

[0006] In the technical solution, the high-pressure hydrogen pipe is connected through the valve seat below the valve body, and enters the lower valve cavity from the air inlet hole on the valve seat. An air guide portion connecting the first cavity and the lower valve cavity is opened in the piston member, and the gas enters the first cavity from the air guide portion. The gas transmission joint is connected with the pipeline. After the hydrogen enters the pipeline from the gas transmission joint, it is burned and used. During operation, if the pressure in the first cavity increases, the gas pressure acting on the head end face of the piston member will increase because the diameter of the head end is larger than the sliding section. When the gas pressure acting on the upper surface of the head end of the piston member is greater than the elastic force of the spring sleeved on the sliding section, the piston member slides downward and disconnects the air inlet hole. As the rear end gas continues to be consumed, the pressure in the first cavity will decrease. When the gas pressure acting on the head end is less than the spring force, the piston moves upward, opens the air inlet hole and continues to connect to the high-pressure gas source. The reciprocating cycle dynamically maintains the stability of the outlet pressure. The up and down movement of the piston in the valve cavity will cause the volume of the first cavity, the second cavity and the lower valve cavity to change continuously. By setting the second cavity to be connected to the atmosphere, it is possible to prevent the gas in the first cavity or the lower valve cavity from leaking into the second cavity, causing a pressure difference in the piston body, thereby preventing the piston from failing due to pressure imbalance. At the same time, the technical solution is also provided with a strict sealing structure to prevent dangerous situations caused by hydrogen leakage.

[0007] Under normal temperature conditions, the Y-type sealing ring achieves sealing through the self-sealing effect of the lip. When the Y-type sealing ring is installed in the piston groove and is subjected to external pressure, the lip will generate a pre-compression force and close to the cover to form a seal; as the pressure increases, the lip will further close to the cover to increase the sealing effect. At the same time, the Y-type sealing ring is very effective in sealing under high temperature conditions, but in low temperature environments, the rubber material will harden, resulting in the weakening of the pre-compression force provided by the lip of the Y-type sealing ring. It can be seen from the sealing principle of the Y-type sealing ring that micro-leakage will occur. An O-ring is also provided in this technical solution, and the O-ring can make up for the shortcomings of the Y-ring. The sealing effect of low-pressure gas will not fail under low-temperature conditions, and the low-pressure hydrogen leaking from the Y-ring will be further sealed, so that this combined sealing structure can provide good sealing performance; the sealing characteristics of the Y-ring and the O-ring are combined to form a combined sealing structure. The first seal uses a Y-ring to seal high-pressure hydrogen, and the second seal uses an O-ring to seal low-pressure or normal-pressure hydrogen leaking from the first seal, which greatly improves the dynamic sealing reliability of the pressure reducing valve for hydrogen. After 100,000 endurance tests with the above settings, the hydrogen leakage from the breathing hole was found to be 0ppm, ensuring the safety of the use of fuel cells within the temperature range of -40℃ to 85℃. It can still maintain good sealing performance and adapt to a wider range of application environments.

[0008] Preferably, as an improvement, an extension ring which can be sleeved on the sliding section is further provided at the connection between the second cavity and the sliding portion, the extension ring is slidably matched with the sliding section, and the spring is located outside the extension ring.

[0009] The beneficial effects are as follows: an extension ring sleeved on the sliding section is provided at the connection between the second chamber and the sliding section, and the spring is located on the outside of the extension ring, which plays a role in extending the sliding section but the overall length of the valve body will not be extended, which can effectively reduce the length of the valve body, which is beneficial to the miniaturization of the pressure reducing valve structure. At the same time, under the premise of ensuring double sealing, the length of the piston member is relatively short. On the one hand, the shorter piston body is less likely to tilt during the movement of the piston, and the tilting of the piston often leads to uneven contact of the sealing surface, thereby accelerating the wear of the sealing structure. Through the above-mentioned arrangement, the piston maintains better balance and stability during the movement, avoiding the wear of the sealing structure, thereby extending the service life of the valve body; on the other hand, the setting of the extension ring further constrains the movement of the sliding section, preventing the sliding section from tilting due to uneven force or unstable movement. This constraint allows the piston member to slide more accurately in the valve body, ensuring continuous and stable sealing performance.

[0010] Preferably, as an improvement, a guide ring is provided between the Y-shaped sealing ring and the O-shaped sealing ring at both ends of the piston member, and the guide ring is sleeved on the outer wall of the piston member and slidably cooperates with the valve cavity.

[0011] The beneficial effects are as follows: the reciprocating motion of the piston is guided by setting a guide ring, which is set between the Y-shaped sealing ring and the O-shaped sealing ring, which is convenient for installation and can maximize the distance between the two guide rings. The guide ring serves as the fulcrum for the piston to contact the valve cavity. The larger the spacing, the smaller the deviation angle between the piston axis and the axis of the valve body inner hole, and the better the guiding effect. The contact between the piston and the valve body is more uniform, thereby reducing the friction and wear caused by the tilt, improving the sealing effect, and ensuring the stability and accuracy of the assembly. By setting the guide ring as above, the movement direction of the piston is ensured to be aligned with the direction of the valve body inner hole. The piston can slide stably and smoothly in the valve body, reducing the wear and structural failure caused by misalignment, thereby ensuring the sealing performance and service life of the valve body.

[0012] Preferably, as an improvement, the valve seat includes a flange and an air inlet portion fixed on the flange, the air inlet portion is sealed with the lower valve cavity, the air inlet port is arranged on the air inlet portion, an annular groove is opened at the upper end of the air inlet, and a sealing seat is embedded in the annular groove.

[0013] The beneficial effect is that a sealing seat is embedded in the annular embedding groove opened at the upper end of the air inlet, and the embedding of the sealing seat further improves the sealing effect and enhances the sealing performance of the lower valve cavity.

[0014] Preferably, as an improvement, a tail end is further provided at the end of the sliding section, and the lower cross-section of the tail end is hemispherical.

[0015] The beneficial effects are: the hemispherical tail end will accurately embed into the sealing seat when the piston slides downward, which can effectively cut off the high-pressure gas source during the movement of the piston. The close fit between the hemispherical shape and the sealing seat ensures that the sealing contact surface is uniform and avoids any gas leakage. The hemispherical tail end design enables the piston to maintain a more stable motion trajectory when high-pressure hydrogen passes through, and is self-guided during the downward sliding process, so that the tail end can be accurately embedded in the sealing seat.

[0016] Preferably, as an improvement, a vent hole communicating with the second chamber is opened on the valve body, and a vent plug is provided at the end of the vent hole.

[0017] The beneficial effect is: by setting an exhaust hole connected to the second chamber and designing a vent plug, the second chamber is connected to the atmosphere, which can prevent the gas in the first chamber or the lower valve chamber from leaking into the second chamber and causing a pressure difference in the piston body, thereby preventing the pressure difference from being generated and causing the piston to be unable to move.

[0018] Preferably, as an improvement, the air guide portion includes a plurality of first air holes circumferentially distributed on the side wall of the tail end and a main air hole penetrating the piston member and communicating with the first air holes.

[0019] The beneficial effects are: the lower valve chamber and the first chamber are connected through the first air vent and the main air vent fluid, the high-pressure gas entering from the air inlet enters the lower valve chamber, and enters the first chamber through the first air vent with reduced air pressure, and the arrangement of multiple first air vents in the circumferential direction allows the gas to apply uniform force to the piston body in the circumferential direction, thereby avoiding the lower end face of the piston from being tilted due to uneven force.

[0020] Preferably, as an improvement, the gas delivery connector is sealed and fixed to the end of the upper valve cavity, and a gas delivery hole is opened in the center of the gas delivery connector. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 It is a structural schematic diagram of an embodiment of the present invention;

[0022] Figure 2 for Figure 1 The enlarged schematic diagram of point A in the middle;

[0023] Figure 3 for Figure 1 The enlarged schematic diagram of point B in the middle;

[0024] Figure 4 Schematic diagram of the structure of a piston member according to an embodiment of the present invention. DETAILED DESCRIPTION

[0025] The following is further described in detail through specific implementation methods:

[0026] The figure marks in the drawings of the specification include: valve body 1, sliding part 2, lower valve chamber 3, gas supply connector 4, gas supply hole 5, air inlet hole 6, spring 7, first chamber 8, second chamber 9, exhaust hole 10, vent plug 11, first vent hole 12, main air hole 13, head end 14, sliding section 15, Y-type sealing ring 16, O-type sealing ring 17, extension ring 18, guide ring 19, sealing seat 20, valve seat 21, tail end 22.

[0027] Example

[0028] The embodiment is basically as follows Figure 1-Figure 4 As shown, Figure 1 The combined sealing structure for the dynamic seal of the piston of a high-pressure hydrogen pressure reducing valve shown in the figure comprises a valve body 1 provided with a valve cavity and a piston member slidably arranged in the valve cavity, the valve cavity comprising an upper valve cavity, a sliding portion 2 and a lower valve cavity 3 from top to bottom, the upper valve cavity and the lower valve cavity 3 are connected through the sliding portion 2, a gas delivery connector 4 is provided at the top of the upper valve cavity, the gas delivery connector 4 is sealed and fixed to the end of the upper valve cavity and fixed by bolts, a gas delivery hole 5 is opened in the center of the gas delivery connector 4, a valve seat 21 is further provided under the valve body 1, and an air inlet hole 6 is opened on the valve seat 21; the piston member comprises a sliding The head end 14 is arranged on the upper valve cavity and the sliding section 15 that slides with the sliding part 2, and also includes a spring 7 sleeved on the sliding section 15, the two ends of the spring 7 are respectively against the bottom surface of the upper valve cavity and the lower surface of the head end 14, the diameter of the head end 14 is larger than the sliding section 15, the piston member reciprocates to adjust the opening and closing of the air inlet 6, and the head end 14 of the piston member divides the upper valve cavity into a first cavity 8 and a second cavity 9 connected to the atmosphere, specifically: the valve body 1 is provided with an exhaust hole 10 connected to the second cavity 9, and the end of the exhaust hole 10 is provided with a vent plug 11; in addition, as shown in FIG. Figure 2 and Figure 3 As shown, the outer peripheries of the head end 14 and the sliding section 15 are fixedly sleeved with a Y-shaped sealing ring 16 and an O-shaped sealing ring 17 , and the Y-shaped sealing ring 16 is respectively arranged at the top of the head section and the tail of the sliding section 15 .

[0029] In the present technical solution, the high-pressure hydrogen pipe is connected through the valve seat 21 below the valve body 1, and enters the lower valve chamber 3 from the air inlet 6 on the valve seat 21. An air guide portion connecting the first chamber 8 and the lower valve chamber 3 is opened in the piston member, and the gas enters the first chamber 8 from the air guide portion. The gas supply connector 4 is connected to the pipeline. After the hydrogen enters the pipeline from the gas supply connector 4, it is burned and used. During operation, if the pressure in the first chamber 8 increases, since the diameter of the head end 14 is larger than the sliding section 15, the gas pressure acting on the head end 14 of the piston member will increase. When the gas pressure acting on the upper surface of the head end 14 of the piston member is greater than the elastic force of the spring 7 sleeved on the sliding section 15, the piston member slides downward and disconnects the air inlet 6; due to the continuous consumption of the rear end gas, the pressure in the first chamber 8 will decrease. When the gas pressure acting on the head end 14 is less than the force of the spring 7, the piston moves up, opens the air inlet 6 and continues to connect to the high-pressure gas source, and the reciprocating cycle dynamically maintains the stability of the outlet pressure. The up and down movement of the piston in the valve cavity will cause the internal volumes of the first cavity 8, the second cavity 9 and the lower valve cavity 3 to change continuously. By providing an exhaust hole 10 connected to the second cavity 9 and designing a vent plug 11, the second cavity 9 is connected to the atmosphere. This can prevent the gas in the first cavity 8 or the lower valve cavity 3 from leaking into the second cavity 9, causing a pressure difference in the piston body, thereby preventing the piston from failing due to pressure imbalance. At the same time, the technical solution is also provided with a tight sealing structure to prevent dangerous situations caused by hydrogen leakage.

[0030] Under normal temperature conditions, the Y-type sealing ring 16 achieves sealing through the self-sealing effect of the lip. When the Y-type sealing ring 16 is installed in the piston groove and is subjected to external pressure, the lip will generate a pre-compression force and close to the cover to form a seal; as the pressure increases, the lip will further close to the cover to increase the sealing effect. At the same time, the sealing effect of the Y-type sealing ring 16 is very effective in a high temperature environment, but in a low temperature environment, the rubber material will harden, resulting in the weakening of the pre-compression force provided by the lip of the Y-type sealing ring 16. It can be seen from the sealing principle of the Y-type sealing ring 16 that micro-leakage will occur. In this technical solution, an O-ring 17 is provided, and the O-ring 17 can make up for the shortcomings of the Y-ring 16. The sealing effect of low-pressure gas will not fail under low-temperature conditions, and the low-pressure hydrogen leaking from the Y-ring 16 will be further sealed, so that this combined sealing structure can provide good sealing performance; the combined sealing structure is based on the sealing characteristics of the Y-ring 16 and the O-ring 17. The first seal uses the Y-ring 16 to seal the high-pressure hydrogen, and the second seal uses the O-ring 17 to seal the low-pressure or normal-pressure hydrogen leaking from the first seal, which greatly improves the dynamic sealing reliability of the pressure reducing valve for hydrogen. After 100,000 durability tests with the above settings, it was found that the hydrogen leakage from the breathing hole was 0ppm, ensuring the safety of the use of fuel cells within the temperature range of -40°C to 85°C. It can still maintain good sealing performance and adapt to a wider range of application environments.

[0031] like Figure 1 and Figure 3 As shown, in this embodiment, the connection between the second cavity 9 and the sliding portion 2 is further provided with an extension ring 18 that can be sleeved on the sliding section 15. The extension ring 18 is slidably matched with the sliding section 15, and the spring 7 is located on the outside of the extension ring 18, which plays a role in extending the sliding portion 2, but the overall length of the valve body 1 will not be extended, which can effectively reduce the length of the valve body 1, which is conducive to the miniaturization of the pressure reducing valve structure. At the same time, under the premise of ensuring double sealing, the length of the piston member is relatively short. On the one hand, the shorter piston body is less likely to tilt during the piston movement. The tilting of the piston often leads to uneven contact of the sealing surface, thereby accelerating the wear of the sealing structure. Through the above-mentioned arrangement, the piston maintains better balance and stability during the movement, avoids the wear of the sealing structure, and thus extends the service life of the valve body 1; on the other hand, the arrangement of the extension ring 18 further constrains the movement of the sliding section 15, preventing the sliding section 15 is tilted due to uneven force or unstable movement. This constraint allows the piston to slide more accurately in the valve body 1, ensuring continuous and stable sealing performance; a guide ring 19 is provided between the Y-ring 16 and the O-ring 17 at both ends of the piston. The guide ring 19 is sleeved on the outer wall of the piston and slidably cooperates with the valve cavity. The guide ring guides the reciprocating motion of the piston. The guide ring 19 is arranged between the Y-ring 16 and the O-ring 17, which is convenient for installation and can maximize the distance between the two guide rings 19. The guide ring 19 serves as the fulcrum for the contact between the piston and the valve cavity. The larger the spacing, the smaller the deviation angle between the piston axis and the axis of the inner hole of the valve body 1, the better the guiding effect can be provided, and the contact between the piston and the valve body 1 is more uniform, thereby reducing the friction and wear caused by the tilt, improving the sealing effect, and ensuring the stability and accuracy of the component. By setting the guide ring 19 as mentioned above, it is ensured that the movement direction of the piston is aligned with the direction of the inner hole of the valve body 1, and the piston can slide stably and smoothly in the valve body 1, reducing wear and structural failure caused by misalignment, thereby ensuring the sealing performance and service life of the valve body 1.

[0032] In this embodiment, Figure 4As shown, a tail end 22 is also provided at the end of the sliding section 15, and the lower cross-section of the tail end 22 is hemispherical. The hemispherical tail end 22 will accurately embed into the sealing seat 20 when the piston member slides downward, and can effectively cut off the high-pressure gas source during the movement of the piston member. The hemispherical shape and the sealing seat 20 are closely matched to ensure that the sealing contact surface is uniform; the valve seat 21 includes a flange plate and an air inlet portion fixed on the flange plate, the air inlet portion is sealed with the lower valve cavity 3, the air inlet is arranged on the air inlet portion, and an annular embedding groove is opened at the upper end of the air inlet, and a sealing seat 20 is embedded in the annular embedding groove. The sealing effect is further improved by embedding the sealing seat 20, and the sealing of the lower valve cavity 3 is ensured when the tail end 22 is embedded in the sealing seat 20. An air guide portion connecting the first chamber 8 and the lower valve chamber 3 is opened in the piston member, and the air guide portion includes a plurality of first air holes 12 circumferentially distributed on the side wall of the tail end 22 and a main air hole 13 that passes through the piston member and is connected to the first air holes 12. The lower valve chamber 3 and the first chamber 8 are fluidically connected through the first air holes 12 and the main air holes 13. The high-pressure gas entering from the air inlet enters the lower valve chamber 3, and enters the main air holes 13 through the first air holes 12 and the first chamber 8 with reduced air pressure. The circumferential arrangement of the plurality of first air holes 12 allows the gas to apply uniform force to the piston body in the circumferential direction, thereby preventing the lower end face of the piston member from being tilted due to uneven force.

[0033] The above is only an embodiment of the present invention, and the common knowledge such as the known specific technical solutions and / or characteristics in the solution is not described in detail here. It should be pointed out that for those skilled in the art, without departing from the technical solution of the present invention, several modifications and improvements can be made, which should also be regarded as the protection scope of the present invention, and these will not affect the effect of the implementation of the present invention and the practicality of the patent. The scope of protection required by this application shall be based on the content of its claims, and the specific implementation methods and other records in the specification can be used to interpret the content of the claims.

Claims

1. A combined sealing structure for a high-pressure hydrogen pressure reducing valve piston dynamic seal, comprising a valve body provided with a valve cavity and a piston member slidably arranged in the valve cavity, the valve cavity comprising an upper valve cavity, a sliding portion and a lower valve cavity from top to bottom, the upper valve cavity and the lower valve cavity are connected through the sliding portion, a gas transmission joint is provided at the top of the upper valve cavity, a valve seat is also provided below the valve body, and an air inlet hole is opened on the valve seat, characterized in that: The piston member includes a head end slidably arranged in the upper valve cavity and a sliding section slidably matched with the sliding part, and also includes a spring sleeved on the sliding section. The diameter of the head end is larger than that of the sliding section. The reciprocating sliding of the piston member can adjust the opening and closing of the air inlet hole. The head end divides the upper valve cavity into a first cavity and a second cavity connected to the atmosphere. An air guide portion connecting the first cavity and the lower valve cavity is opened in the piston member. The outer periphery of the head end and the sliding section are sleeved with a Y-type sealing ring and an O-type sealing ring. The Y-type sealing ring is respectively arranged at the top of the head section and the tail of the sliding section.

2. The combined sealing structure for dynamic sealing of a high-pressure hydrogen pressure reducing valve piston according to claim 1, characterized in that: An extension ring which can be sleeved on the sliding section is also provided at the connection between the second cavity and the sliding part. The extension ring is slidably matched with the sliding section, and the spring is located outside the extension ring.

3. The combined sealing structure for dynamic sealing of a high-pressure hydrogen pressure reducing valve piston according to claim 2, characterized in that: A guide ring is arranged between the Y-shaped sealing ring and the O-shaped sealing ring at both ends of the piston, and the guide ring is sleeved on the outer wall of the piston and slidably matched with the valve cavity.

4. The combined sealing structure for dynamic sealing of a high-pressure hydrogen pressure reducing valve piston according to claim 3, characterized in that: The valve seat comprises a flange and an air inlet portion fixed on the flange, the air inlet portion is sealed with the lower valve cavity, the air inlet is arranged on the air inlet portion, an annular groove is opened at the upper end of the air inlet, and a sealing seat is embedded in the annular groove.

5. The combined sealing structure for dynamic sealing of a high-pressure hydrogen pressure reducing valve piston according to claim 4, characterized in that: A tail end is also provided at the end of the sliding section, and the lower cross section of the tail end is hemispherical.

6. A combined sealing structure for dynamic sealing of a high-pressure hydrogen pressure reducing valve piston according to claim 5, characterized in that: The valve body is provided with an exhaust hole which is communicated with the second cavity, and a vent plug is arranged at the end of the exhaust hole.

7. A combined sealing structure for dynamic sealing of a piston of a high-pressure hydrogen pressure reducing valve according to claim 6, characterized in that: The air guide portion comprises a plurality of first air vents circumferentially distributed on the side wall of the tail end and a main air vent that penetrates the piston member and is in communication with the first air vents.

8. The combined sealing structure for dynamic sealing of a high-pressure hydrogen pressure reducing valve piston according to claim 7, characterized in that: The gas transmission joint is sealed and fixed at the end of the upper valve cavity, and a gas transmission hole is opened at the center of the gas transmission joint.

Images