Steady-flow self-balancing type gas pressure regulator

Abstract

The invention relates to the field of gas pressure regulators and discloses a steady-flow self-balancing type gas pressure regulator which comprises a valve body, the left side of the valve body communicates with a gas inlet pipe, the right side of the valve body communicates with a gas outlet pipe, a valve seat is fixedly connected to the center of the interior of the valve body, and a valve port is formed in the center of the valve seat. A positioning cylinder is fixedly connected to the center of the upper end of the valve body, a guide cylinder is fixedly connected into the positioning cylinder, a valve rod extending to the position below a valve port is slidably inserted into the guide cylinder, a valve clack is fixedly connected to the bottom of the valve rod, a lubricating mechanism is arranged on the outer side of the guide cylinder, and the valve rod and the guide cylinder are lubricated through the lubricating mechanism. Therefore, surge caused by frequent friction between the valve rod and the guide cylinder is avoided. When the valve rod slides up and down in the guide cylinder, lubricating grease can be supplemented to the contact position of the valve rod and the guide cylinder, so that the lubricating function is started, surge caused by frequent friction between the valve rod and the guide cylinder is avoided, and the pressure regulating effect is guaranteed.

Description

Technical Field

[0001] This invention relates to the field of gas pressure regulators, and more specifically, to a flow-stabilizing self-balancing gas pressure regulator. Background Technology

[0002] A gas pressure regulator, commonly known as a pressure reducing valve, is a gas pressure regulating device specifically designed for use in gas transmission and distribution systems. It is widely used in gas transmission and distribution projects. Its function is to automatically adjust the gas outlet pressure, stabilizing it within a specific pressure range to meet the user's required pressure value and usage requirements.

[0003] The valve disc of a pressure reducing valve is the main actuating component, and it often experiences frequent up-and-down vibrations due to changes in the gas inlet pressure, a phenomenon known as surging. This surging leads to unstable gas outlet pressure, and in severe cases, can affect downstream users' access to gas. Therefore, it is essential to provide a gas pressure regulator that can effectively prevent surging.

[0004] Existing gas pressure regulators reduce the force between the valve disc and valve seat by placing a rubber gasket between them, thereby slowing down the valve disc's surge frequency. They also reduce the angle between the valve disc and valve seat and minimize unnecessary surge by placing a positioning cylinder and a matching guide cylinder at the top of the valve seat, allowing the valve stem to move linearly up and down within the guide cylinder.

[0005] However, since the valve stem is in direct contact with the inner wall of the guide cylinder, there is friction between the valve stem and the guide cylinder. Furthermore, due to the lack of lubrication between the valve stem and the guide cylinder, frequent friction between the valve stem and the inner wall of the guide cylinder will not only cause surging, but also cause wear on the valve stem. This can easily cause gas to leak out between the valve stem and the guide cylinder, thus affecting the pressure regulation effect.

[0006] Therefore, a self-balancing gas pressure regulator with stable flow is proposed. Summary of the Invention

[0007] The purpose of this invention is to provide a self-balancing gas pressure regulator with stable flow to solve the problems mentioned in the background art.

[0008] To solve the above problems, the present invention adopts the following technical solution.

[0009] A self-balancing gas pressure regulator with stable flow includes a valve body. An inlet pipe is connected to the left side of the valve body, and an outlet pipe is connected to the right side of the valve body. A valve seat is fixedly connected to the center of the valve body, and a valve port is opened at the center of the valve seat. A positioning cylinder is fixedly connected to the center of the upper end of the valve body. A guide cylinder is fixedly connected inside the positioning cylinder. A valve stem extending to below the valve port is slidably inserted into the guide cylinder. A valve disc is fixedly connected to the bottom of the valve stem.

[0010] The upper end of the valve stem is provided with a pressure regulating mechanism, which enables the valve disc to achieve a self-balancing state, thereby ensuring that the gas can flow stably through the valve port.

[0011] The outer side of the guide cylinder is equipped with a lubrication mechanism, which lubricates the valve stem and the guide cylinder to avoid damage caused by frequent friction between the valve stem and the guide cylinder.

[0012] Furthermore, the pressure regulating mechanism includes a bottom cover fixedly connected to the upper end of the positioning cylinder, a top cover above the bottom cover, a diaphragm sandwiched between the top cover and the bottom cover, and the top cover and the bottom cover being fixedly connected by bolts and nuts.

[0013] Furthermore, the upper end of the valve stem extends through to the top of the diaphragm, a base is fixedly fitted on the outer annular side of the valve stem below the diaphragm, a gasket is slidably fitted on the outer annular side of the valve stem above the diaphragm, and a fixing nut is threadedly connected to the outer annular side of the valve stem above the gasket.

[0014] Furthermore, a tube is fixedly connected to the center of the upper end face of the top cover, a fixing ring is fixedly sleeved on the upper end of the annular outer surface of the tube, a cover is fixedly connected to the upper end face of the fixing ring by bolts and nuts, a threaded rod is threadedly connected to the center of the upper end face of the cover, a cover plate is rotatably connected to the bottom of the threaded rod, and a pressure adjusting spring is provided between the cover plate and the gasket.

[0015] Furthermore, slots are provided on the upper end face of the gasket near the outer edge and on the lower end face of the cover plate near the outer edge, and the upper and lower ends of the pressure regulating spring are respectively engaged in the slots at the corresponding positions.

[0016] Furthermore, the lubrication mechanism includes a cylinder sleeved on the outside of the positioning cylinder, and the cylinder is fixedly connected to the positioning cylinder by four equidistantly distributed guide tubes in an annular shape. The inner annular side of the guide cylinder is provided with four equidistant guide holes.

[0017] Furthermore, a piston is slidably connected between the guide cylinder and the positioning cylinder, and the piston is fixedly connected to the base by four equally spaced annular support rods.

[0018] Furthermore, a filter screen is fixedly connected inside the air intake pipe near the valve body. A sleeve is fixedly connected to the inner wall of the air intake pipe on the left side of the filter screen. A rotating rod is rotatably inserted into the sleeve. A scraper is fixedly connected to the right end of the rotating rod, and an impeller is fixedly connected to the left end of the rotating rod. A branch pipe is connected to the outer wall of the air intake pipe at the lower left side of the filter screen, and a material cylinder is threaded onto the branch pipe.

[0019] Furthermore, two retaining rings are symmetrically fixedly connected inside the air intake pipe near the pipe opening, and ball bearings are provided between the two retaining rings.

[0020] Furthermore, the outer annular side of the air intake pipe is connected to a vertical cylinder located between the two retaining rings, and a sliding rod is slidably inserted inside the vertical cylinder. The outer annular side of the sliding rod is elastically connected to the upper end face of the vertical cylinder by a return spring.

[0021] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0022] 1. This solution uses a lubrication mechanism on the outside of the guide cylinder to replenish lubricating grease at the contact point between the valve stem and the guide cylinder as the valve stem slides up and down inside the guide cylinder. This lubrication process is activated, preventing frequent friction between the valve stem and the guide cylinder from causing surging and ensuring the pressure regulating effect.

[0023] 2. This solution uses a filter screen installed inside the intake pipe to filter out iron oxide powder and iron sulfide powder generated in the gas transmission pipeline, preventing them from entering the valve body and causing blockage at the valve port.

[0024] 3. This solution uses gas as the driving force to rotate the impeller, which in turn drives the scraper to rotate on the left side of the filter screen, thereby scraping off the dust attached to the filter screen and facilitating dust cleaning.

[0025] 4. This solution involves installing two retaining rings and ball bearings at the inlet of the air intake pipe. The diameter of the ball bearings is larger than the through hole of the retaining rings but smaller than the inner diameter of the air intake pipe. When a leak occurs at the outlet pipe, the air pressure at the air intake pipe will increase instantaneously, which will blow the ball bearings toward the through hole at the center of the right retaining ring. Then, under the action of the pressure difference, the ball bearings will be attracted into the through hole of the right retaining ring, thereby cutting off the continued supply of gas and avoiding safety accidents. Attached Figure Description

[0026] Figure 1 This is a three-dimensional schematic diagram of the overall structure of the present invention. Figure 1 ;

[0027] Figure 2 This is a three-dimensional schematic diagram of the overall structure of the present invention. Figure 2 ;

[0028] Figure 3 for Figure 1 A cross-sectional diagram;

[0029] Figure 4 for Figure 2 A cross-sectional diagram;

[0030] Figure 5 An exploded view of the connection between the lubrication mechanism and the valve stem;

[0031] Figure 6 for Figure 3 Enlarged diagram of point A in the diagram.

[0032] Explanation of markings in the diagram:

[0033] 1. Valve body; 11. Inlet pipe; 12. Outlet pipe; 13. Positioning cylinder; 14. Bottom cover; 15. Diaphragm; 16. Top cover; 2. Valve stem; 21. Valve disc; 22. Base; 23. Gasket; 24. Fixing nut; 25. Valve seat; 26. Support rod; 3. Cylinder; 31. Guide pipe; 32. Guide cylinder; 33. Guide hole; 34. Piston; 4. Pipe body; 41. Fixing ring; 42. Cover; 43. Threaded rod; 44. Cover plate; 45. Pressure adjusting spring; 5. Filter screen; 51. Sleeve; 52. Rotating rod; 53. Scraper; 54. Impeller; 55. Material cylinder; 56. Branch pipe; 6. Retaining ring; 61. Ball bearing; 62. Vertical cylinder; 63. Slide rod; 64. Return spring. Detailed Implementation

[0034] The technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are within the scope of protection of the present invention.

[0035] Please see Figures 1 to 6 A self-balancing gas pressure regulator with stable flow includes a valve body 1. An inlet pipe 11 is connected to the left side of the valve body 1, and an outlet pipe 12 is connected to the right side of the valve body 1. A valve seat 25 is fixedly connected to the center of the valve body 1. A valve port is opened at the center of the valve seat 25. A positioning cylinder 13 is fixedly connected to the center of the upper end of the valve body 1. A guide cylinder 32 is fixedly connected inside the positioning cylinder 13. A valve stem 2 extending to below the valve port is slidably inserted into the guide cylinder 32. A valve disc 21 is fixedly connected to the bottom of the valve stem 2.

[0036] The upper end of the valve stem 2 is provided with a pressure regulating mechanism, which includes a bottom cover 14 fixedly connected to the upper end of the positioning cylinder 13. A top cover 16 is provided above the bottom cover 14. A diaphragm 15 is sandwiched between the top cover 16 and the bottom cover 14. The top cover 16 and the bottom cover 14 are fixedly connected by bolts and nuts. The upper end of the valve stem 2 extends through to the top of the diaphragm 15. A base 22 is fixedly fitted on the annular outer side of the valve stem 2 below the diaphragm 15. A pad is slidably fitted on the annular outer side of the valve stem 2 above the diaphragm 15. The valve stem 2 has a fixed nut 24 threadedly connected to the annular outer side above the gasket 23. The top cover 16 has a tube 4 fixedly connected to the center of its upper end face. The tube 4 has a fixed ring 41 fixedly fitted on the upper end of its annular outer side face. The upper end face of the fixed ring 41 is fixedly connected to a cover 42 by bolts and nuts. The upper end face of the cover 42 has a threaded rod 43 threadedly connected to the center of its upper end face. The bottom of the threaded rod 43 is rotatably connected to a cover plate 44. A pressure adjusting spring 45 is provided between the cover plate 44 and the gasket 23.

[0037] By adopting the above technical solution, the inlet of the inlet pipe 11 is connected to the gas transmission pipeline, and the gas transmission pipe 12 is connected to the gas pipeline of the downstream user. As gas is continuously input into the valve body 1, the internal pressure of the valve body 1 continuously increases, thereby pushing the valve disc 21 to move downward, causing the valve disc 21 to disengage from the valve port on the valve seat 25. Gas can then flow into the outlet pipe 12 through the valve port. During the downward movement of the valve disc 21, the valve stem 2 will slide down along the guide cylinder 32, thereby causing the diaphragm 15 to indent downward, causing the pressure regulating spring 45 on the gasket 23 to rebound. When the pressure reaches 2.8 kPa, the valve disc 21 and the pressure regulating spring 45 maintain balance, and the gas is stably delivered to the downstream user. When the downstream flow demand increases, the valve disc 21 moves downward to increase the opening degree of the valve port, thereby increasing the gas flow. When the pressure is reduced, valve disc 21 moves upward, causing valve stem 2 to slide upward along guide cylinder 32, which in turn causes diaphragm 15 to bulge upward, compressing pressure regulating spring 45. During the continuous rebound and compression of pressure regulating spring 45, valve disc 21 achieves self-balancing, thereby ensuring stable flow of gas through valve body 1. When it is necessary to adjust the pressure of pressure regulating spring 45, the cover plate 44 can be raised or lowered by rotating threaded rod 43, thereby completing pressure adjustment. Slots are provided on the upper end face of gasket 23 near the outer edge and on the lower end face of cover plate 44 near the outer edge. The upper and lower ends of pressure regulating spring 45 are respectively engaged in the slots at the corresponding positions, so that pressure regulating spring 45 will not deviate from cover plate 44 and gasket 23 during the up and down movement, ensuring normal force on pressure regulating spring 45 and thus ensuring stable pressure regulation.

[0038] like Figures 3 to 6As shown, a lubrication mechanism is provided on the outside of the guide cylinder 32. The lubrication mechanism includes a cylinder 3 sleeved on the outside of the positioning cylinder 13. The cylinder 3 and the positioning cylinder 13 are fixedly connected by four equidistantly distributed guide pipes 31. The inner side of the guide cylinder 32 is provided with four equidistantly distributed guide holes 33. A piston 34 is slidably connected between the guide cylinder 32 and the positioning cylinder 13. The piston 34 and the base are fixedly connected by four equidistantly distributed support rods 26.

[0039] By adopting the above technical solution, the valve stem 2, during its up-and-down sliding within the guide cylinder 32, drives the support rod 26 to move up and down, thereby causing the piston 34 to slide up and down between the guide cylinder 32 and the positioning cylinder 13. The four guide pipes 31 are made of stainless steel, thus supporting the cylinder 3. Both ends of the four guide pipes 31 are connected to the cylinder 3 and the positioning cylinder 13 respectively. Each of the four guide pipes 31 is equipped with a one-way valve. When the piston 34 moves upward, a suction force is generated inside the guide pipe 31, causing the one-way valve inside the guide pipe 31 to open, allowing the lubricating grease in the cylinder 3 to flow into the guide cylinder 3 through the guide pipe 31. In the cavity between valve stem 2 and piston 34, when piston 34 moves downward, pressure is generated in the cavity between guide cylinder 32 and piston 34, thereby closing the one-way valve in guide pipe 31. The lubricating grease in the cavity between guide cylinder 32 and piston 34 enters the contact position between valve stem 2 and guide cylinder 32 through guide hole 33, thereby playing a lubricating role, preventing gaps from being generated between valve stem 2 and guide cylinder 32 due to friction, allowing gas to enter the bottom cover 15 and affecting the pressure regulation effect, thereby preventing the friction between valve stem 2 and guide cylinder 32 from causing surge, extending the service life of the valve, and ensuring the pressure regulation effect.

[0040] like Figure 3 and Figure 4 As shown, a filter screen plate 5 is fixedly connected inside the air intake pipe 11 near the valve body 1. A sleeve 51 is fixedly connected to the inner wall of the air intake pipe 11 on the left side of the filter screen plate 5. A rotating rod 52 is rotatably inserted into the sleeve 51. A scraper 53 is fixedly connected to the right end of the rotating rod 52, and an impeller 54 is fixedly connected to the left end of the rotating rod 52. A branch pipe 56 is connected to the outer wall of the air intake pipe 11 at the lower left side of the filter screen plate 5. A material cylinder 55 is threaded onto the branch pipe 56. Two retaining rings 6 are symmetrically fixedly connected to the air intake pipe 11 near the pipe opening, and a ball bearing 61 is provided between the two retaining rings 6. A vertical cylinder 62 is connected to the annular outer side of the air intake pipe 11 between the two retaining rings 6. A sliding rod 63 is slidably inserted into the vertical cylinder 62. The annular outer side of the sliding rod 63 is elastically connected to the upper end face of the vertical cylinder 62 by a return spring 64.

[0041] By adopting the above technical solution, since gas transmission pipelines are mostly made of metal, prolonged contact with gas will cause corrosion, resulting in the formation of iron oxide dust and iron sulfide dust. This dust is blown towards the valve body 1 by the airflow. A filter screen 5 is installed inside the air inlet pipe 11, which blocks the iron oxide dust and iron sulfide dust as they pass through it, preventing them from entering the valve body 1 and clogging the valve port. Furthermore, when the airflow passes through the impeller 54, it creates a thrust on the impeller 54, driving it to rotate. This, in turn, causes the scraper 53 to rotate on the left side of the filter screen 5, continuously scraping off the iron oxide dust and iron sulfide dust adhering to the filter screen 5. Dust and iron sulfide dust enter the feed cylinder 55 through the branch pipe 56, preventing iron oxide dust and iron sulfide dust from clogging the filter screen 5 and facilitating the cleaning of iron oxide dust and iron sulfide dust. When the pipeline connected to the exhaust pipe 12 leaks, it will cause the pressure in the intake pipe 11 to increase instantaneously, thereby blowing the ball 61 between the two baffle rings 6 into the through hole in the center of the right baffle ring 6, thus cutting off the gas supply and preventing safety accidents. After the fault is repaired, the slide rod 63 can be pressed, and the slide rod 63 slides down along the vertical cylinder 62 to push the ball 61 down, so that the ball 61 disengages from the right baffle ring 6, thereby allowing the gas supply to be restored. After the slide rod 63 is released, the slide rod 63 is reset under the action of the return spring 64.

[0042] Instructions for use: Connect the gas supply pipe 12 to the downstream user's gas pipeline. As gas continuously enters the valve body 1, the internal pressure of the valve body 1 continuously increases, thereby pushing the valve disc 21 downward. This causes the valve disc 21 to disengage from the valve port on the valve seat 25, allowing the gas to flow into the gas outlet pipe 12 through the valve port. During the downward movement of the valve disc 21, it drives the valve stem 2 to slide down along the guide cylinder 32, thereby causing the diaphragm 15 to indent downward. This causes the pressure regulating spring 45 on the gasket 23 to rebound. When the pressure reaches 2.8 kPa, the valve disc 21 and... The pressure regulating spring 45 maintains balance, ensuring a stable supply of gas to downstream users. When downstream flow demand increases, valve disc 21 moves downward to increase the valve opening, thereby increasing the gas flow. When downstream flow demand decreases, valve disc 21 moves upward, causing valve stem 2 to slide upward along guide cylinder 32, which in turn causes diaphragm 15 to bulge upward, compressing the pressure regulating spring 45. Through the continuous rebound and compression of the pressure regulating spring 45, valve disc 21 achieves self-balancing, ensuring a stable gas flow through valve body 1. As rod 2 slides up and down within guide cylinder 32, it drives support rod 26 to move up and down, thereby causing piston 34 to slide up and down between guide cylinder 32 and positioning cylinder 13. The four guide pipes 31 are made of stainless steel, thus supporting cylinder 3. Both ends of the four guide pipes 31 are connected to cylinder 3 and positioning cylinder 13 respectively, and each of the four guide pipes 31 is equipped with a one-way valve. When piston 34 moves upward, suction is generated inside the guide pipe 31, causing the one-way valve inside the guide pipe 31 to open, allowing lubricating oil in cylinder 3 to flow in. Grease flows into the cavity between the guide cylinder 32 and the piston 34 through the guide pipe 31. When the piston 34 moves downward, pressure is generated in the cavity between the guide cylinder 32 and the piston 34, thereby closing the one-way valve in the guide pipe 31. The lubricating grease in the cavity between the guide cylinder 32 and the piston 34 enters the contact position between the valve stem 2 and the guide cylinder 32 through the guide hole 33, thereby playing a lubricating role, preventing friction between the valve stem 2 and the guide cylinder 32 from causing surging, extending the service life of the valve, and ensuring the pressure regulating effect.

[0043] The above description is merely a preferred embodiment of the present invention; however, the scope of protection of the present invention is not limited thereto. Any equivalent substitutions or modifications made by those skilled in the art within the scope of the technology disclosed in the present invention, based on the technical solution and its improved concepts, should be covered within the scope of protection of the present invention.

Claims

1. A self-balancing gas pressure regulator with stable flow, characterized in that: Includes a valve body (1), with an air inlet pipe (11) connected to the left side of the valve body (1) and an air outlet pipe (12) connected to the right side of the valve body (1). A valve seat (25) is fixedly connected to the center of the valve body (1), and a valve port is opened at the center of the valve seat (25). A positioning cylinder (13) is fixedly connected to the center of the upper end of the valve body (1), and a guide cylinder (32) is fixedly connected inside the positioning cylinder (13). A valve stem (2) extending to the lower part of the valve port is slidably inserted into the guide cylinder (32), and a valve disc (21) is fixedly connected to the bottom of the valve stem (2). The upper end of the valve stem (2) is provided with a pressure regulating mechanism. The valve disc (21) can be made to reach a self-balancing state through the pressure regulating mechanism, thereby ensuring that the gas can flow through the valve port stably. The guide cylinder (32) is provided with a lubrication mechanism on the outside. The lubrication mechanism lubricates the valve stem (2) and the guide cylinder (32) to avoid the surge caused by frequent friction between the valve stem (2) and the guide cylinder (32).

2. The self-balancing gas pressure regulator according to claim 1, characterized in that: The pressure regulating mechanism includes a bottom cover (14) fixedly connected to the upper end of the positioning cylinder (13), a top cover (16) is provided above the bottom cover (14), a membrane (15) is sandwiched between the top cover (16) and the bottom cover (14), and the top cover (16) and the bottom cover (14) are fixedly connected by bolts and nuts.

3. The self-balancing gas pressure regulator according to claim 2, characterized in that: The upper end of the valve stem (2) extends through to the top of the diaphragm (15). A base (22) is fixedly fitted on the outer annular side of the valve stem (2) below the diaphragm (15). A gasket (23) is slidably fitted on the outer annular side of the valve stem (2) above the diaphragm (15). A fixing nut (24) is threadedly connected to the outer annular side of the valve stem (2) above the gasket (23).

4. The self-balancing gas pressure regulator according to claim 3, characterized in that: A tube body (4) is fixedly connected to the center of the upper end face of the top cover (16). A fixing ring (41) is fixedly sleeved on the upper end of the annular outer side of the tube body (4). A cover (42) is fixedly connected to the upper end face of the fixing ring (41) by bolts and nuts. A threaded rod (43) is threadedly connected to the center of the upper end face of the cover (42). A cover plate (44) is rotatably connected to the bottom of the threaded rod (43). A pressure adjusting spring (45) is provided between the cover plate (44) and the gasket (23).

5. The self-balancing gas pressure regulator according to claim 4, characterized in that: The upper end face of the gasket (23) near the outer edge and the lower end face of the cover plate (44) near the outer edge are provided with slots, and the upper and lower ends of the pressure regulating spring (45) are respectively engaged in the slots at the corresponding positions.

6. The self-balancing gas pressure regulator according to claim 5, characterized in that: The lubrication mechanism includes a cylinder (3) sleeved on the outside of the positioning cylinder (13). The cylinder (3) and the positioning cylinder (13) are fixedly connected by four equidistant guide tubes (31) arranged in an annular pattern. The inner side of the guide cylinder (32) is provided with four equidistant guide holes (33).

7. The self-balancing gas pressure regulator according to claim 6, characterized in that: A piston (34) is slidably connected between the guide cylinder (32) and the positioning cylinder (13), and the piston (34) is fixedly connected to the base by four equally spaced support rods (26) in a ring.

8. The self-balancing gas pressure regulator according to claim 1, characterized in that: A filter screen plate (5) is fixedly connected inside the air inlet pipe (11) near the valve body (1). A sleeve (51) is fixedly connected to the inner wall of the air inlet pipe (11) on the left side of the filter screen plate (5). A rotating rod (52) is rotatably inserted into the sleeve (51). A scraper (53) is fixedly connected to the right end of the rotating rod (52). An impeller (54) is fixedly connected to the left end of the rotating rod (52). A branch pipe (56) is connected to the outer wall of the air inlet pipe (11) at the lower left side of the filter screen plate (5). A feed cylinder (55) is threaded onto the branch pipe (56).

9. The self-balancing gas pressure regulator according to claim 1, characterized in that: The air intake pipe (11) has two retaining rings (6) fixedly connected symmetrically on the left and right sides near the pipe opening, and a ball bearing (61) is provided between the two retaining rings (6).

10. The self-balancing gas pressure regulator according to claim 9, characterized in that: The outer annular side of the air intake pipe (11) is connected to a vertical cylinder (62) located between two retaining rings (6). A sliding rod (63) is slidably inserted inside the vertical cylinder (62). The outer annular side of the sliding rod (63) is elastically connected to the upper end face of the vertical cylinder (62) by a return spring (64).

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