Water pipe anti-explosion connector

Abstract

The water pipe anti-explosion connector comprises a connector body, a water inlet channel and a water outlet channel are arranged in the connector body, and the water inlet channel is communicated with the water outlet channel; an inclined rod is arranged on the upper portion of the water inlet channel of the connector body, an air storage cavity is formed in the inclined rod and communicated with the water inlet channel, the air storage cavity faces upwards in an inclined mode, air is stored through the air storage cavity after water is introduced, and 78% of nitrogen which is not prone to being dissolved in water exists in the air. Nitrogen can enter a gap of a crystal structure of ice crystals to relieve pressure in a pipeline, space expansion is needed when water is frozen, ice can enter an air storage cavity, the function that the water pipe anti-explosion connector is not prone to burst when the water pipe anti-explosion connector is frozen is achieved, the structure is simple, assembly and installation are convenient, economic cost input is low, and the water pipe anti-explosion connector belongs to the technical field of water pipes.

Description

Technical Field

[0001] The invention relates to the technical field of water pipes, and in particular to an explosion-proof connector for water pipes. Background Art

[0002] In modern buildings and industrial facilities, the safe operation of water pipe systems is crucial. Especially in cold regions or low-temperature environments, the water in the water pipes freezes and expands, which can easily cause the water pipes and their connectors to burst, causing serious property losses and safety hazards. Therefore, water pipe explosion-proof technology has always been a key area of ​​concern in the industry.

[0003] At present, most of the explosion-proof mechanisms for water pipes on the market mainly rely on rebound mechanisms to deal with the expansion pressure generated when water freezes. This rebound mechanism is usually composed of multiple complex parts, including elastic elements, transmission components, and precision control components. When water expands when it freezes, the rebound mechanism absorbs part of the pressure through the deformation of the elastic element and uses the transmission components to disperse the force, trying to stabilize the air pressure of the pipeline to prevent bursting. However, this design has many defects that are difficult to overcome.

[0004] From the perspective of structural complexity, the combination of multiple components of the rebound mechanism makes its overall structure extremely complex, and each component needs to be precisely matched and installed, which places extremely high demands on the production and processing process. Any slight deviation may affect the performance of the rebound mechanism, resulting in its inability to effectively play an explosion-proof role. In the processing process, complex structures mean higher processing difficulty. The manufacture of elastic elements requires special materials and processes to ensure that they have stable and reliable elastic properties; transmission components require high-precision processing to ensure accurate force transmission. This not only increases the technical difficulty in the production process, but also greatly increases the scrap rate, further pushing up production costs. Summary of the invention

[0005] In view of the technical problems existing in the prior art, the purpose of the present invention is to provide a water pipe explosion-proof connector, which stores air through an air storage chamber after water is passed through. 78% of the air is nitrogen that is not easily soluble in water. When the water in the connector body freezes, the nitrogen can enter the gaps in the crystal structure of the ice crystals to relieve the pressure in the pipeline. Water needs space to expand when it freezes, and the ice can enter the air storage chamber, thereby realizing the function that the connector is not easy to burst when frozen. The structure is simple, the assembly and installation are convenient, and the economic cost investment is low.

[0006] In order to achieve the above object, the present invention adopts the following technical solution:

[0007] A water pipe explosion-proof connector comprises a connector body, wherein a water inlet channel and a water outlet channel are arranged in the connector body, and the water inlet channel is connected with the water outlet channel; the connector body is provided with an inclined rod at the upper part of the water inlet channel, and an air storage chamber is arranged in the inclined rod, and the air storage chamber is connected with the water inlet channel, and the air storage chamber is inclined upward.

[0008] As a preferred embodiment, the water inlet channel is oriented horizontally, and the water outlet of the water outlet channel faces downward.

[0009] As a preferred embodiment, the water inlet channel includes a main water flow section and a water flow chamber, the main water flow section is connected to the water flow chamber, the water flow chamber is connected to the water outlet channel, the inner diameter of the water flow chamber is larger than the inner diameter of the main water flow section, and the lower end of the air storage chamber is arranged at the main water flow section and is connected to the main water flow section.

[0010] As a preferred embodiment, a water inlet pipe connection structure is provided at the water inlet end of the water inlet channel, and a water outlet pipe connection structure is provided at the water outlet end of the water outlet channel.

[0011] As a preferred embodiment, the water pipe explosion-proof connector also includes a water inlet acceleration joint, which is connected to the water inlet pipe connecting structure. A tapered section and a straight section are arranged in the water inlet acceleration joint. The inner diameter of the tapered section gradually decreases with the direction of water flow. The tapered section is connected to the straight section, and the straight section is connected to the water inlet channel.

[0012] As a preferred embodiment, a first external thread is provided on the outer periphery of the water inlet acceleration joint, and the water inlet pipe connection structure is a first internal thread, and the connection between the water inlet acceleration joint and the connector body is achieved by screwing the first external thread into the first internal thread.

[0013] As a preferred embodiment, a guide surface is provided on the outer periphery of the water inlet acceleration joint close to the straight-through section, and the guide surface is located in the water inlet channel.

[0014] As a preferred embodiment, the water pipe explosion-proof connector also includes a sealing ring, the outer diameter of the guide surface is smaller than the outer diameter of the first external thread, the sealing ring is sleeved on the guide surface, the diameter of the first internal thread is larger than the inner diameter of the water inlet channel, and the sealing ring is compressed between the water inlet acceleration joint and the connector body.

[0015] As a preference, a one-way pressurizing valve is provided at the tail end of the air storage chamber.

[0016] As a preferred embodiment, the one-way pressurizing valve includes a pressurizing valve body, a valve core, a spring, and a supporting and fixing seat. A through hole is provided at the tail end of the air storage chamber. The pressurizing valve body is tightly plugged into the through hole and welded and fixed. An air passage is provided in the pressurizing valve body. The supporting and fixing seat, the spring, and the valve core are arranged in the air passage in sequence from the inside to the outside. The supporting and fixing seat is fixedly connected to the bottom of the air passage. A through air hole is provided in the supporting and fixing seat. The spring is compressed between the supporting and fixing seat and the valve core. A blocking portion is provided in the middle of the air passage. The valve core abuts against the blocking portion to block the air passage. A second internal thread is provided in the upper portion of the air passage.

[0017] The present invention has the following advantages:

[0018] 1. An inclined rod is set on the upper part of the water inlet channel in the connector body, and an air storage chamber is configured therein, and the air storage chamber is inclined upward. After water is passed through, air is stored in the air storage chamber. 78% of the air is nitrogen. When the water in the connector body freezes, the nitrogen can enter the gaps in the crystal structure of the ice crystals to relieve the pressure in the pipeline. The water needs space to expand when it freezes, and the ice can enter the air storage chamber, so that the connector is not easy to burst when it freezes. The structure is simple, easy to assemble and install, and the economic cost investment is low.

[0019] 2. The inner diameter of the water passage chamber is larger than that of the main water passage section, so that the water passage chamber can store more air. Under the action of power and gravity, the water flow will first flow to the lower part of the water passage chamber instead of filling the upper part of the water passage chamber first. When the water flows back to fill the upper part of the water passage chamber, the air in the upper part of the water passage chamber will be squeezed into the air storage chamber, so that more air can be stored in the air storage chamber. If the water freezes, more nitrogen will penetrate into the gaps in the crystal structure of the ice crystals, so that the connector and the water pipe connected to the connector are not easily broken by the expansion of water freezing. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0021] Figure 1 It is a schematic structural diagram of the connector body of the first embodiment.

[0022] Figure 2 This is a schematic structural diagram of a connector body according to the second embodiment.

[0023] Figure 3 This is a schematic diagram of the structure of the water pipe explosion-proof connector of Example 3.

[0024] Figure 4 This is a schematic diagram of the structure of the water inlet acceleration joint of Example 3.

[0025] Figure 5 This is a schematic diagram of the structure in which the one-way pressurizing valve of Example 4 is installed at the tail end of the air storage chamber.

[0026] Figure 6 for Figure 5 Enlarged view of point A.

[0027] Among them, 1. connector body; 2. water inlet channel; 3. water outlet channel; 4. inclined rod; 5. air storage chamber; 6. water inlet pipe connection structure; 7. water outlet pipe connection structure; 8. main water flow section; 9. water flow chamber; 10. water inlet acceleration joint; 11. tapered section; 12. straight section; 13. first external thread; 14. first internal thread; 15. guide surface; 16. sealing ring; 17. one-way pressurizing valve; 18. pressurizing valve body; 19. valve core; 20. spring; 21. support and fixing seat; 22. air duct; 23. air hole; 24. blocking part; 25. second internal thread; 26. chamfer; 27. through hole; 28. blocking surface. DETAILED DESCRIPTION

[0028] The following will be combined with the accompanying drawings in the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work belong to the protection scope of the present invention.

[0029] Embodiment 1

[0030] like Figure 1As shown, a water pipe explosion-proof connector includes a connector body 1, in which a water inlet channel 2 and a water outlet channel 3 are arranged, and the water inlet channel 2 is connected with the water outlet channel 3; the connector body 1 is provided with an inclined rod 4 at the upper part of the water inlet channel 2, and an air storage chamber 5 is arranged in the inclined rod 4, and the air storage chamber 5 is connected with the water inlet channel 2, and the long strip air storage chamber 5 is in the same direction as the inclined rod 4, and the air storage chamber 5 is inclined upward. The implementation principle of the present application is that when the connector body 1 is empty at the beginning and there is no water, the water inlet channel 2, the water outlet channel 3 and the air storage chamber 5 are all filled with air. When water starts to flow from the water inlet channel 2 through the water outlet channel 3, the water flow expels the air in the water inlet channel 2 and the water outlet channel 3 to the outside, but the density of air is smaller than that of water. Due to the effect of gravity, during the process of the water inlet channel 2 and the water outlet channel 3 being filled with water, the air in the air storage chamber 5 is still stored in the air storage chamber 5. The water continues to compress the air in the air storage chamber 5 until the internal pressure of the entire connector body 1 is consistent, because 78% of the air is nitrogen, nitrogen is not easily soluble in water under normal temperature and low temperature environment, and nitrogen is not easily frozen. Therefore, nitrogen occupies a certain space in the air storage chamber 5 under normal water temperature and water pressure. When the temperature gradually decreases, the water in the water inlet channel 2 and the water outlet channel 3 is frozen and begins to freeze. The freezing process of water is relatively slow. The ice is in the form of ice crystals. Ice crystals are crystal structures formed by water molecules arranged according to certain rules. There are gaps in the crystal structure, so the water will expand during the freezing process. When the water in contact with nitrogen also freezes, the nitrogen will penetrate into the gaps in the crystal structure, thereby leaving a certain space for the expansion of the frozen water. In order to stabilize the internal air pressure, the water will enter the air storage chamber 5 to freeze, thereby protecting the connector and not being easily broken by the expansion of the frozen water. When the temperature rises, the ice slowly melts into water, and the nitrogen is released from the ice crystals, and the nitrogen will re-enter the air storage chamber 5 upward.

[0031] Compared with the prior art water pipe explosion-proof mechanism, the water pipe explosion-proof connector of the present application has a simple structure, is easy to manufacture, is easy to assemble and install, and has a low economic cost. The air in the air storage chamber 5 enters the gaps in the crystal structure of the ice crystals. Water freezes and needs space to expand. Ice can enter the air storage chamber to achieve explosion-proof. After testing, the explosion-proof effect is significant.

[0032] The water inlet channel 2 is oriented horizontally, and the angle between the water inlet channel 2 and the water outlet channel 3 is a right angle. The water outlet of the water outlet channel 3 faces downward, which can change the direction of the water flow. The tail end of the water inlet channel 2 is a blocking surface 28. When the water pipe explosion-proof connector starts to pass water, the water flows through the blocking surface 28 and then flows downward from the water outlet channel 3, which can provide a buffering process for the water flow. After testing, the angle between the water inlet channel 2 and the water outlet channel 3 is a right angle, which can better store air in the air storage chamber 5.

[0033] The present application prefers that the inclination angle of the air storage chamber 5 relative to the water inlet channel 2 is 30°, but the present application does not limit the inclination angle of the air storage chamber 5 relative to the water inlet channel 2. The water pipe explosion-proof connector is usually a connector between multiple water pipes. After the water inlet channel 2 and the water outlet channel 3 of the water pipe explosion-proof connector are installed with water pipes, the air storage chamber 5 is located at the upper part of the water inlet channel 2. The inclination angle of the air storage chamber 5 relative to the water inlet channel 2 can realize the function of storing air in the air storage chamber 5 after water passes through, which falls within the protection scope of the present application.

[0034] The water inlet end of the water inlet channel 2 is provided with a water inlet pipe connection structure 6, and the water outlet end of the water outlet channel 3 is provided with a water outlet pipe connection structure 7. The water inlet pipe connection structure 6 and the water outlet pipe connection structure 7 of the present application are both threaded connection structures, which can be internal threads or external threads, that is, the connection between the connector and the water pipe can be a threaded connection. Of course, the present application is not limited to threaded connection, and can be selected as a clamp connection, a hot melt connection, a capacitor connection, etc., all of which are within the protection scope of the present application.

[0035] The connector body 1 is made of copper, stainless steel, or plastic.

[0036] Embodiment 2

[0037] like Figure 2 As shown, the difference between this embodiment and the first embodiment is that the water inlet channel 2 includes a main water flow section 8 and a water flow chamber 9, the main water flow section 8 is connected to the water flow chamber 9, the water flow chamber 9 is connected to the water outlet channel 3, the lower end of the air storage chamber 5 is arranged at the main water flow section 8 and is connected to the main water flow section 8, the inner diameter of the water flow chamber 9 is larger than the inner diameter of the main water flow section 8, so that the water flow chamber 9 can store more air, and the water flow is affected by the power and gravity, and the water flow will preferentially flow to the lower part of the water flow chamber 9 instead of preferentially filling the upper part of the water flow chamber 9. When the water flow returns to fill the upper part of the water flow chamber 9, the air in the upper part of the water flow chamber 9 will be squeezed into the air storage chamber 5, so that more nitrogen can be stored in the air storage chamber 5, so that when the water freezes, more nitrogen will penetrate into the gaps in the crystal structure of the ice crystals, so that the connector is not easily broken by the expansion of water freezing.

[0038] Embodiment 3

[0039] like Figure 3 and Figure 4As shown, the difference between this embodiment and the second embodiment is that the water pipe explosion-proof connector also includes a water inlet acceleration joint 10, which is connected to the water inlet pipe connection structure 6, and a tapered section 11 and a straight section 12 are arranged in the water inlet acceleration joint 10. The inner diameter of the tapered section 11 gradually decreases with the direction of water flow, the water outlet of the tapered section 11 is the same as the inner diameter of the straight section 12, the tapered section 11 is connected to the straight section 12, and the straight section 12 is connected to the water inlet channel 2. The water inlet acceleration joint 10 is used to connect with the water inlet pipe. When the water inlet acceleration joint 10 is connected with the water inlet pipe, the tapered section 11 is connected with the pipe of the water inlet pipe. Based on the continuity equation principle of the law of conservation of mass, for incompressible fluids (such as water), under the condition of stable flow, the fluid flow rate through any cross section of the pipe is the same, which means that in the narrower part of the pipe (where the cross-sectional area is reduced), in order to maintain the same flow rate, the flow rate becomes larger. Therefore, the inner diameter of the tapered section 11 of the present application gradually decreases with the direction of water flow, and the water flow rate increases in the gradually decreasing direction. The inside of the contraction section 11 gradually becomes larger along the direction of the water flow. As the water flow speed increases, the water flows directly into the water cavity 9 through inertia, and will first quickly fill the water cavity 9 before returning to fill the main water flow section 8. That is, a certain amount of air will remain before the main water flow section 8 is filled. When the main water flow section 8 is also filled, the remaining air will be squeezed into the air storage cavity 5, so that more gas can be stored in the air storage cavity 5, so that when the water freezes, more nitrogen will penetrate into the gaps in the crystal structure of the ice crystals, thereby making the connector less likely to be broken by the expansion of water freezing.

[0040] The outer periphery of the water inlet acceleration joint 10 is provided with a first external thread 13, and the water inlet pipe connection structure 6 is a first internal thread 14. The first external thread 13 is screwed into the first internal thread 14 to realize the connection between the water inlet acceleration joint 10 and the connector body 1, which facilitates the disassembly and assembly of the water inlet acceleration joint 10. The first external thread 13 is only partially screwed into the first internal thread 14, and the partially exposed first external thread 13 is used to connect with the water inlet pipe.

[0041] The outer periphery of the water inlet acceleration joint 10 is provided with a guide surface 15 near the straight-through section 12, and the guide surface 15 is located in the main water flow section 8. The guide surface 15 provides convenience for the installation of the water inlet acceleration joint 10. The guide surface 15 can assist the operator to quickly and accurately locate the position of the water inlet acceleration joint 10, so that the first external thread 13 can be smoothly screwed into the first internal thread 14, ensuring the guide docking between the water inlet acceleration joint 10 and the connector body 1, and speeding up the installation speed. The inner side of the guide surface 15 is provided with a chamfer 26, and the chamfer 26 assists in guiding the guide surface 15 to be inserted into the main water flow section 8.

[0042] The water pipe explosion-proof connector also includes a sealing ring 16. The outer diameter of the guide surface 15 is smaller than the outer diameter of the first external thread 13. The sealing ring 16 is sleeved on the guide surface 15. The diameter of the first internal thread 14 is larger than the inner diameter of the water inlet channel 2. The sealing ring 16 is compressed between the water inlet acceleration joint 10 and the connector body 1. The sealing ring 16 effectively prevents water leakage and ensures a reliable sealing effect even in environments with different air pressures. The outer diameter of the guide surface 15 is smaller than the outer diameter of the first external thread 13, and the diameter of the first internal thread 14 is larger than the inner diameter of the water inlet channel 2, which provides sufficient compression space for the sealing ring 16 and ensures a good sealing contact area.

[0043] The material of the water inlet acceleration joint 10 is copper, stainless steel, or plastic.

[0044] Embodiment 4

[0045] like Figure 5 and Figure 6 As shown, the difference between this embodiment and the first, second and third embodiments is that a one-way pressure valve 17 is provided at the tail end of the air storage chamber 5. When the water in the water pipe explosion-proof connector freezes and the ice melts due to the temperature rise, the nitrogen in the air storage chamber 5 may be carried away by the water flow due to the internal air pressure change, and the nitrogen will be reduced a little compared with before. At this time, a certain amount of air is injected through the one-way pressure valve 17 to ensure that the nitrogen in the air storage chamber 5 is sufficient, so as to prepare for the next water freezing explosion, and ensure that the water pipe explosion-proof connector and the water pipe connected to the connector are not easily broken by the expansion of water freezing when the water freezes next time.

[0046] The one-way pressurizing valve 17 includes a pressurizing valve body 18, a valve core 19, a spring 20, and a supporting and fixing seat 21. A through hole 27 is provided at the tail end of the air storage chamber 5. The pressurizing valve body 18 is fixedly connected in the through hole 27. A through air passage 22 is provided in the pressurizing valve body 18. The supporting and fixing seat 21, the spring 20, and the valve core 19 are sequentially arranged in the air passage 22 from the inside to the outside. The supporting and fixing seat 21 is fixedly connected to the bottom of the air passage 22. A through air hole 23 is provided in the supporting and fixing seat 21. The spring 20 is compressed between the supporting and fixing seat 21 and the valve core 19. A blocking portion 24 is provided in the middle of the air passage 22. The valve core 19 abuts against the blocking portion 24 through the elastic force of the spring 20 to block the air passage 22, so as to prevent the air in the air storage chamber 5 from escaping to the outside. A second internal thread 25 is provided at the upper portion of the air passage 22. When it is necessary to add air to the air storage chamber 5, the output end of the pressurizing device is threadedly connected to the second internal thread 25, and air is added to the air passage 22. The valve core 19 is pushed by the pressure, and the spring 20 is further compressed, so that there is a gap between the valve core 19 and the blocking part 24, and the pressurized air smoothly enters the air storage chamber 5 through the air passage 22. When the pressurizing device is released, the spring 20 rebounds, and the valve core 19 returns to its position to block the air passage 22. The valve core 19 is provided with a sealing groove on the side facing the blocking part 24, and a rubber ring is embedded in the sealing groove to enhance the sealing effect between the valve core 19 and the blocking part 24.

[0047] The present invention is further described above with the aid of specific embodiments. However, it should be understood that the specific description here should not be construed as limiting the essence and scope of the present invention. Various modifications made to the above embodiments by ordinary technicians in the field after reading this specification are all within the scope of protection of the present invention.

Claims

1. A water pipe explosion-proof connector, characterized in that: The invention comprises a connector body (1), wherein a water inlet channel (2) and a water outlet channel (3) are arranged in the connector body (1), and the water inlet channel (2) is connected to the water outlet channel (3); the connector body (1) is provided with an inclined rod (4) at the upper part of the water inlet channel (2), and an air storage chamber (5) is arranged in the inclined rod (4), and the air storage chamber (5) is connected to the water inlet channel (2), and the air storage chamber (5) is inclined upward.

2. The water pipe explosion-proof connector according to claim 1, characterized in that: The water inlet channel (2) is oriented horizontally, and the water outlet of the water outlet channel (3) is oriented downward.

3. The water pipe explosion-proof connector according to claim 2, characterized in that: The water inlet channel (2) comprises a main water flow section (8) and a water flow chamber (9), the main water flow section (8) is connected to the water flow chamber (9), the water flow chamber (9) is connected to the water outlet channel (3), the inner diameter of the water flow chamber (9) is larger than the inner diameter of the main water flow section (8), and the lower end of the air storage chamber (5) is arranged at the main water flow section (8) and is connected to the main water flow section (8).

4. A water pipe explosion-proof connector according to any one of claims 2 or 3, characterized in that: A water inlet pipe connection structure (6) is provided at the water inlet end of the water inlet channel (2), and a water outlet pipe connection structure (7) is provided at the water outlet end of the water outlet channel (3).

5. The water pipe explosion-proof connector according to claim 4, characterized in that: The water pipe explosion-proof connector also includes a water inlet acceleration joint (10), which is connected to the water inlet pipe connection structure (6), and a tapered section (11) and a straight section (12) are arranged in the water inlet acceleration joint (10), the inner diameter of the tapered section (11) gradually decreases with the direction of water flow, the tapered section (11) is connected to the straight section (12), and the straight section (12) is connected to the water inlet channel (2).

6. The water pipe explosion-proof connector according to claim 5, characterized in that: The outer periphery of the water inlet acceleration joint (10) is provided with a first external thread (13), and the water inlet pipe connection structure (6) is a first internal thread (14). The water inlet acceleration joint (10) is connected to the connector body (1) by screwing the first external thread (13) into the first internal thread (14).

7. The water pipe explosion-proof connector according to claim 6, characterized in that: A guide surface (15) is provided on the outer periphery of the water inlet acceleration joint (10) close to the straight-through section (12), and the guide surface (15) is located in the water inlet channel (2).

8. The water pipe explosion-proof connector according to claim 7, characterized in that: The water pipe explosion-proof connector also includes a sealing ring (16); the outer diameter of the guide surface (15) is smaller than the outer diameter of the first outer thread (13); the sealing ring (16) is sleeved on the guide surface (15); the diameter of the first inner thread (14) is larger than the inner diameter of the water inlet channel (2); and the sealing ring (16) is compressed between the water inlet acceleration joint (10) and the connector body (1).

9. The water pipe explosion-proof connector according to claim 1, characterized in that: A one-way pressurizing valve (17) is provided at the rear end of the air storage chamber (5).

10. The water pipe explosion-proof connector according to claim 9, characterized in that: The one-way pressurizing valve (17) comprises a pressurizing valve body (18), a valve core (19), a spring (20), and a supporting and fixing seat (21). A through hole (27) is provided at the rear end of the air storage chamber (5). The pressurizing valve body (18) and the through hole (27) are tightly plugged and fixed by welding. An air passage (22) is provided in the pressurizing valve body (18). The supporting and fixing seat (21), the spring (20), and the valve core (19) are arranged in sequence from the inside to the outside in the air passage (22). The support fixing seat (21) is fixedly connected to the bottom of the air passage (22), a through air hole (23) is provided in the support fixing seat (21), the spring (20) is compressed between the support fixing seat (21) and the valve core (19), a blocking portion (24) is provided in the middle of the air passage (22), the valve core (19) abuts against the blocking portion (24) to block the air passage (22), and a second internal thread (25) is provided in the upper part of the air passage (22).

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