External cold trap for dilution refrigerator

Abstract

The invention discloses an external cold trap for a dilution refrigerator, and particularly relates to the field of refrigeration and low-temperature engineering, the external cold trap comprises a liquid nitrogen tank, a purification chamber is arranged in the liquid nitrogen tank, a separation unit, a purification unit and a pre-cooling unit are sequentially arranged in an inner cavity of the purification chamber from top to bottom, and a sealing top cover is arranged at the top of the purification chamber; the sealing top cover is provided with an air inlet pipe, an air outlet pipe and a maintenance channel. According to the technical scheme, the pre-cooling unit and the separation unit are additionally arranged on the lower portion and the upper portion of the purification unit formed by activated carbon respectively, so that the heat exchange efficiency of airflow is improved, the cooling time is shortened, and the purpose of improving the purification efficiency is achieved; meanwhile, the separation unit and the copper mesh filter element form a self-purification device, so that the self-pollution effect of the cold trap is avoided; the long-term stable operation of the throttling process and the stability of long-term repeated start-up of the dilution refrigerator can be guaranteed, so that the maintenance period of the dilution refrigerator is greatly prolonged, and very positive significance is achieved for practicability of the dilution refrigerator.

Description

Technical Field

[0001] The present invention relates to the field of refrigeration and cryogenic engineering technology, and more particularly to an external cold trap for a dilution refrigerator. Background Art

[0002] Dilution refrigerator is the core equipment for obtaining ultra-low temperature environment in the millikelvin (mK) temperature range, and has important applications in cutting-edge scientific fields such as quantum computing and condensed matter physics research.

[0003] Due to its structural characteristics, a dilution refrigerator has numerous micron-sized pores or capillary channels distributed internally. During actual operation, the purity of the working gas and the stability of the throttling components directly impact the refrigerator's refrigeration performance and long-term operational stability. Impure working gas can easily clog the channels in extremely low temperatures, potentially leading to refrigeration cycle failure. Therefore, a cold trap is often required in dilution refrigeration systems to maximize working gas purification.

[0004] However, traditional cold traps often fail to fully consider the structural characteristics of the dilution refrigerator itself, often resulting in low purification efficiency, easy clogging, low heat exchange efficiency, and even serious risks such as self-contamination, resulting in frequent maintenance shutdowns, which in turn affects the continuity of the dilution refrigerator's own operation and the reliability of the entire system. Therefore, it is particularly necessary to develop an efficient, stable, and long-maintenance external cold trap to improve the overall performance and continuous operation stability of the dilution refrigerator. Summary of the Invention

[0005] In order to overcome the above-mentioned defects of the prior art, an embodiment of the present invention provides an external cold trap for a dilution refrigerator to solve the problems mentioned in the background art.

[0006] To achieve the above-mentioned object, the present invention provides the following technical solution: an external cold trap for a dilution refrigerator, comprising a liquid nitrogen tank, a purification chamber provided inside the liquid nitrogen tank, the inner cavity of the purification chamber comprising, from top to bottom, a separation unit, a purification unit, and a pre-cooling unit, a sealing top cover provided on the top of the purification chamber, an air inlet pipe, an air outlet pipe, and a maintenance passage provided on the sealing top cover, wherein the air inlet pipe passes through the sealing top cover and extends into the inner cavity of the separation unit;

[0007] A compactor and a copper mesh filter element are provided at the bottom of the air outlet pipe.

[0008] In a preferred embodiment, the separation unit is configured as a cylindrical cavity, and the separation unit is located above the purification unit;

[0009] The pre-cooling unit, the purification unit and the separation unit together constitute the cavity at the lower part of the purification chamber. The lower part of the purification chamber is a cylindrical cavity. The lower part of the purification chamber is welded to the sealing top cover to form the purification chamber.

[0010] The pre-cooling unit is a cylindrical sponge copper with multiple small cavities inside, which is placed on the bottom layer of the lower part of the purification chamber to slow down the flow rate of the incoming flow used for pre-cooling, extend the heat exchange time of the incoming flow, and reduce the temperature of the incoming flow; the net purification unit is configured as a section of cylindrical activated carbon, located above the pre-cooling unit, which plays the role of filtering the incoming gas.

[0011] In a preferred embodiment, the liquid nitrogen tank serves as a cavity for receiving liquid nitrogen and is generally cylindrical. An assembly port is provided on the upper end surface of the liquid nitrogen tank, and an exhaust hole is provided on the top of the assembly port.

[0012] In a preferred embodiment, a high-pressure pipeline through hole is opened at the connection between the sealing top cover and the air inlet pipe, and a low-pressure pipeline through hole is opened at the connection between the sealing top cover and the air outlet pipe, and the high-pressure pipeline through hole and the low-pressure pipeline through hole are symmetrically arranged along the center of the sealing top cover;

[0013] The air inlet pipe is configured as a high-cleanliness circular pipe, one end of the air inlet pipe is close to the bottom of the lower part of the purification chamber, and the other end of the air inlet pipe is aligned and passes through the high-pressure pipe through-hole;

[0014] The air outlet pipe is configured as a section of high-cleanliness circular pipe, and is positioned in the through hole of the low-pressure pipe.

[0015] In a preferred embodiment, a compressor seat is provided at the bottom of the low-pressure pipeline through hole, and the compressor seat is configured as a section of round pipe with internal threads.

[0016] In a preferred embodiment, the copper mesh filter element is assembled in the compressor seat, and the copper mesh filter element is screwed into the compressor seat and compressed on the sealing top cover;

[0017] The compressor is a section of round tube, half of the cross section of the compressor channel is hexagonal, and the other half is circular, and a portion of the length of the outer portion of the round tube corresponding to the compressor is provided with threads.

[0018] The present invention also includes a method for manufacturing an external cold trap for a dilution refrigerator, the specific steps of which are as follows:

[0019] S1: The liquid nitrogen tank is made of low thermal conductivity material, with a flat lower end and an assembly opening on the upper end. The diameter of the assembly opening is larger than the diameter of the lower part of the purification chamber and smaller than the diameter of the sealing top cover. A semicircular vent is left at the assembly opening to relieve nitrogen pressure.

[0020] S2: The sealing top cover is provided with through holes for high-pressure and low-pressure pipes. A compression seat is welded on the bottom surface of the sealing top cover, which is concentric with the through hole for the low-pressure pipe. The compression seat is a section of circular tube with internal threads. A maintenance channel is provided at the center of the sealing top cover.

[0021] S3: The lower part of the purification chamber is used to house the pre-cooling unit. The diameter of the pre-cooling unit is slightly larger than the inner diameter of the lower part of the purification chamber, so that the pre-cooling unit and the purification chamber have an interference fit. A channel is left on the pre-cooling unit to pass through the air inlet pipe. The lower part of the purification chamber is used to house the purification unit. The purification unit is located above the pre-cooling unit and is made of activated carbon. After the pre-cooled gas flows through the purification unit, impurities are removed.

[0022] S4: The final space is the separation unit, which is a cavity used to separate the fine activated carbon particles blown up by the gas. The air inlet pipe is a clean pipe that passes through the through hole of the high-pressure pipe and is airtightly welded to the sealing top cover. One end of the air inlet pipe reaches the bottom of the purification chamber, and a gap is left between the other end and the upper end of the sealing top cover.

[0023] S5: The exhaust pipe is welded to the through hole of the low-pressure pipeline, with a gap between one end and the upper end surface of the sealing top cover, and the other end does not pass through the sealing top cover; the copper mesh filter element is assembled in the compressor seat, screwed into the compressor seat and compressed on the sealing top cover; the compressor is a section of circular tube, half of whose channel cross-section is hexagonal and the other half is circular, and threads are left on part of the outer length of the circular tube.

[0024] The technical effects and advantages of the present invention are as follows:

[0025] 1. The present invention enhances heat exchange and purification efficiency: by providing a pre-cooling unit, the temperature of the gas entering the purification unit is effectively reduced, the adsorption efficiency and service life of the activated carbon are improved, and the residence time of the gas in the purification chamber is extended, thereby enhancing heat exchange;

[0026] 2. The present invention can prevent self-contamination: the combined design of the separation unit and the copper mesh filter element can effectively prevent fine activated carbon particles from entering the subsequent pipeline with the air flow, thus avoiding the self-contamination problem of the cold trap;

[0027] 3. The present invention can extend the maintenance cycle: the efficient purification and anti-pollution design ensures the long-term stable operation of the throttling process, reduces the risk of blockage, and thus significantly extends the maintenance cycle of the dilution refrigerator;

[0028] 4. The structural design of the present invention is reasonable: the structure of each component is clear, and the design of the maintenance channel also provides convenience for possible maintenance. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 It is a schematic diagram of the overall structure of the present invention.

[0030] Figure 2 It is a schematic cross-sectional view of the overall structure of the present invention.

[0031] Figure 3 It is a schematic diagram of the combined structure of the compactor and compactor seat of the present invention.

[0032] Figure 4 It is a schematic diagram of the assembly structure of the purification chamber and the sealing top cover of the present invention.

[0033] Figure 5 It is a schematic diagram of the assembly structure of the vent hole and the assembly port of the present invention.

[0034] Figure 6 It is a schematic structural diagram of the compactor of the present invention.

[0035] The figures are marked as follows: 1 liquid nitrogen tank, 2 purification chamber, 3 pre-cooling unit, 4 purification unit, 5 separation unit, 6 air inlet pipe, 7 air outlet pipe, 8 compressor, 9 copper mesh filter element, 10 maintenance channel, 11 assembly port, 12 vent, 13 sealing top cover, 14 high-pressure pipe through hole, 15 low-pressure pipe through hole, 16 compressor seat, 17 lower part of the purification chamber. DETAILED DESCRIPTION

[0036] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. 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 making creative efforts are within the scope of protection of the present invention.

[0037] The present invention provides Figure 1-6 The external cold trap for a dilution refrigerator shown in the figure includes a liquid nitrogen tank 1, a purification chamber 2 is provided inside the liquid nitrogen tank 1, and the inner cavity of the purification chamber 2 includes, from top to bottom, a separation unit 5, a purification unit 4, and a pre-cooling unit 3. A sealed top cover 13 is provided on the top of the purification chamber 2, and an air inlet pipe 6, an air outlet pipe 7, and a maintenance channel 10 are provided on the sealed top cover 13. The air inlet pipe 6 passes through the sealed top cover 13 and extends into the inner cavity of the separation unit 5.

[0038] The liquid nitrogen tank 1 is the cold source part of the cold trap. It is a cylindrical cavity as a whole and is used to contain liquid nitrogen. The upper end surface of the liquid nitrogen tank 1 is provided with an assembly port 11, which is used to connect to the purification chamber 2 or add liquid nitrogen. The top of the assembly port 11 is provided with an exhaust hole 12, which is used to discharge nitrogen generated by evaporation of liquid nitrogen to maintain pressure balance in the tank;

[0039] The bottom of the outlet pipe 7 is provided with a compressor 8 and a copper mesh filter element 9; the pre-cooling unit 3, the purification unit 4 and the separation unit 5 together form the cavity of the lower part 17 of the purification chamber. The lower part 17 of the purification chamber is a cylindrical cavity. The lower part 17 of the purification chamber is welded with the sealing top cover 13 to form the purification chamber 2; the purification chamber 2 is the core part of the gas purification; the upper part of the purification chamber 2 is the sealing top cover 13, and the sealing top cover 13 is provided with multiple through holes: a high-pressure pipe through hole 14 is provided at a diameter of 7 cm for connecting the inlet pipe 6 A low-pressure pipe through hole 15 is provided at a diameter of 6 cm for connecting the outlet pipe 7; a through hole with a diameter of 10 mm is also provided at the center of the sealing top cover 13, which serves as a maintenance channel 10 to facilitate maintenance or replacement of the adsorbent inside the purification chamber 2; a compression device seat 16 is processed on the bottom surface of the sealing top cover 13, which is concentric with the low-pressure pipe through hole 15; the compression device seat 16 is a section of a circular tube with an internal thread, which is used to install and fix the copper mesh filter element 9 and the compression device 8;

[0040] The separation unit 5 is configured as a cylindrical cavity and is located above the purification unit 4, providing a sedimentation and separation space to prevent fine activated carbon particles that may be blown up during gas flow from entering the subsequent outlet pipe 7 along with the air flow.

[0041] The precooling unit 3 is a cylindrical sponge copper with many small cavities inside. It is placed at the bottom layer of the lower part 17 of the purification chamber. The sponge copper has a porous structure and good thermal conductivity. When the gas to be purified flows through here, it can fully exchange heat with the purification chamber wall cooled by liquid nitrogen, thereby obtaining precooling. At the same time, its porous structure also helps to slow down the gas flow rate, prolong the heat exchange time, improve the precooling effect, and may initially condense or adsorb some high-boiling point impurities; the net purification unit 4 is set as a section of cylindrical activated carbon, located above the precooling unit 3. The activated carbon has a huge specific surface area and a developed pore structure, and is a commonly used high-efficiency adsorbent; when the precooled gas flows through the activated carbon, most of the impurities therein (such as air, moisture, etc.) will be adsorbed, thereby achieving the purpose of deep purification.

[0042] A high-pressure pipeline through hole 14 is opened at the connection between the sealing top cover 13 and the air inlet pipe 6, and a low-pressure pipeline through hole 15 is opened at the connection between the sealing top cover 13 and the air outlet pipe 7. The high-pressure pipeline through hole 14 and the low-pressure pipeline through hole 15 are symmetrically arranged along the center of the sealing top cover 13;

[0043] The air inlet pipe 6 is a section of electrolytically polished clean circular tube to ensure the smoothness of its inner surface and low outgassing rate; one end of the air inlet pipe 6 passes through the high-pressure pipe through-hole 14 on the sealing top cover 13 and is sealed therewith, and the other end of the air inlet pipe 6 extends to the bottom of the lower part 17 of the purification chamber, that is, below the pre-cooling unit 3, to ensure that the gas can flow from bottom to top through each purification level. One end of the air inlet pipe 6 is close to the bottom of the lower part 17 of the purification chamber, and the other end of the air inlet pipe 6 is aligned and passes through the high-pressure pipe through-hole 14;

[0044] The outlet pipe 7 is also a section of electrolytically polished clean round tube, which is processed on the low-pressure pipe through hole 15 of the sealing top cover 13 and is sealed therewith; the inlet end of the outlet pipe 7 is located at the upper part of the separation unit 5 and is used to discharge the purified clean gas;

[0045] A compressor seat 16 is provided at the bottom of the low-pressure pipeline through hole 15 , and the compressor seat 16 is configured as a section of round pipe with internal threads.

[0046] The copper mesh filter element 9 is assembled in the compactor seat 16. The copper mesh filter element 9 is screwed into the compactor seat 16 and then pressed against the sealing top cover 13. The copper mesh filter element 9 is made of a fine copper mesh and is used to further filter out tiny solid particles that may be present in the gas, serving as the last physical barrier.

[0047] The compression device 8 is a section of circular tube, half of which has an inner hexagonal cross-section and the other half is circular. The outer portion of the circular tube corresponding to the compression device 8 is provided with threads. The compression device 8 is screwed into the inner thread of the compression device seat 16 through its outer thread, thereby pressing the copper mesh filter element 9 to the corresponding position of the sealing top cover 13 to ensure the sealing and fixation of the filter element. The inner hexagonal shape facilitates the tightening operation using tools.

[0048] The present invention also includes a method for manufacturing an external cold trap for a dilution refrigerator, the specific steps of which are as follows:

[0049] S1: The liquid nitrogen tank 1 is made of a low thermal conductivity material, with a flat lower end surface and an assembly opening 11 on the upper end surface. The diameter of the assembly opening 11 is larger than the diameter of the lower portion 17 of the purification chamber, but smaller than the diameter of the sealing top cover 13. The assembly opening 11 also has a semicircular vent 12 for nitrogen pressure relief.

[0050] S2: The sealing top cover 13 is provided with a high-pressure pipe through hole 14 and a low-pressure pipe through hole 15. A compression seat 16 is welded on the bottom surface of the sealing top cover 13, which is concentric with the low-pressure pipe through hole 15. The compression seat 16 is a section of circular tube with internal threads. A maintenance channel 10 is provided at the center of the sealing top cover 13.

[0051] S3: The lower portion 17 of the purification chamber is used to house the pre-cooling unit 3. The diameter of the pre-cooling unit 3 is slightly larger than the inner diameter of the lower portion 17 of the purification chamber, so that the pre-cooling unit 3 and the purification chamber 2 have an interference fit. A passage is left on the pre-cooling unit 3 to pass through the air inlet pipe 6. The lower portion 17 of the purification chamber is used to house the purification unit 4. The purification unit 4 is located above the pre-cooling unit 3 and is composed of activated carbon. After the pre-cooled gas flows through the purification unit 4, impurities are removed.

[0052] S4: The final space is the separation unit 5, which is a cavity used to separate the fine activated carbon particles blown up by the gas. The air inlet pipe 6 is a clean pipe that passes through the high-pressure pipe through-hole 14 and is airtightly welded to the sealing top cover 13. One end of the air inlet pipe 6 directly reaches the bottom of the lower part 17 of the purification chamber, and a gap is left between the other end face and the upper end face of the sealing top cover 13.

[0053] S5: The air outlet pipe 7 is welded to the through hole 15 of the low-pressure pipe, with a gap between one end and the upper end surface of the sealing top cover 13, and the other end does not pass through the sealing top cover 13; the copper mesh filter element 9 is assembled in the compressor seat 16, and is pressed against the sealing top cover 13 after being screwed into the compressor seat 16; the compressor 8 is a section of circular tube, half of whose channel cross-section is hexagonal and the other half is circular, and a thread is left on part of the length outside the circular tube.

[0054] During operation, the gas to be purified enters through the inlet pipe 6, first passing through the pre-cooling unit 3 to cool and decelerate, then flows through the purification unit 4 where impurities are adsorbed by the activated carbon, then passes through the separation unit 5 to remove any possible particulate matter, and finally, after further filtration through the copper mesh filter element 9, the clean gas is output through the outlet pipe 7. The entire purification chamber 2 is cooled by the liquid nitrogen tank 1, maintaining a low temperature environment to improve adsorption efficiency. This provides an external cold trap with optimized structure, high purification efficiency, excellent heat exchange performance, and effective self-contamination prevention, which is used to improve the overall performance of the dilution refrigerator and ensure its continuous operation and stability.

[0055] Finally, a few points should be explained: First, in the description of this application, it should be noted that, unless otherwise specified or limited, the terms "mounted," "connected," and "connected" should be understood in a broad sense, and may refer to mechanical or electrical connections, internal communication between two components, or direct connection. "Up," "down," "left," and "right" are only used to indicate relative positional relationships. When the absolute positions of the objects being described change, the relative positional relationships may also change.

[0056] Secondly: The drawings of the embodiments disclosed in the present invention only involve structures related to the embodiments disclosed in the present invention. Other structures may refer to conventional designs. The same embodiment and different embodiments of the present invention may be combined with each other without conflict.

[0057] Finally: The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. An external cold trap for a dilution refrigerator, characterized in that: The invention comprises a liquid nitrogen tank (1), wherein a purification chamber (2) is provided inside the liquid nitrogen tank (1), wherein the inner cavity of the purification chamber (2) comprises a separation unit (5), a purification unit (4) and a pre-cooling unit (3) in order from top to bottom, and a sealing top cover (13) is provided on the top of the purification chamber (2), wherein an air inlet pipe (6), an air outlet pipe (7) and a maintenance channel (10) are provided on the sealing top cover (13), wherein the air inlet pipe (6) passes through the sealing top cover (13) and extends into the inner cavity of the separation unit (5); A compactor (8) and a copper mesh filter element (9) are provided at the bottom of the air outlet pipe (7).

2. The external cold trap for a dilution refrigerator according to claim 1, characterized in that: The separation unit (5) is configured as a cylindrical cavity, and the separation unit (5) is located above the purification unit (4); The precooling unit (3), the purification unit (4) and the separation unit (5) together form a cavity of the lower portion (17) of the purification chamber. The lower portion (17) of the purification chamber is a cylindrical cavity. The lower portion (17) of the purification chamber is welded to the sealing top cover (13) to form the purification chamber (2). The pre-cooling unit (3) is a cylindrical sponge copper with multiple small cavities inside, which is placed on the bottom layer of the lower part (17) of the purification chamber; the net purification unit (4) is configured as a section of cylindrical activated carbon, which is located above the pre-cooling unit (3).

3. The external cold trap for a dilution refrigerator according to claim 1, characterized in that: The liquid nitrogen tank (1) serves as a cavity for receiving liquid nitrogen and is generally cylindrical. An assembly port (11) is provided on the upper end surface of the liquid nitrogen tank (1), and an exhaust hole (12) is provided on the top of the assembly port (11).

4. The external cold trap for a dilution refrigerator according to claim 2, characterized in that: A high-pressure pipeline through hole (14) is provided at the connection between the sealing top cover (13) and the air inlet pipe (6), and a low-pressure pipeline through hole (15) is provided at the connection between the sealing top cover (13) and the air outlet pipe (7), wherein the high-pressure pipeline through hole (14) and the low-pressure pipeline through hole (15) are symmetrically arranged along the center of the sealing top cover (13); The air inlet pipe (6) is configured as a high-cleanliness circular pipe, one end of the air inlet pipe (6) is close to the bottom of the lower part (17) of the purification chamber, and the other end of the air inlet pipe (6) is aligned and passes through the high-pressure pipe through hole (14); The air outlet pipe (7) is configured as a section of a high-cleanliness circular pipe, and is positioned in the low-pressure pipeline through hole (15).

5. The external cold trap for a dilution refrigerator according to claim 4, characterized in that: A compression device seat (16) is provided at the bottom of the low-pressure pipeline through hole (15), and the compression device seat (16) is configured as a section of a circular pipe with an internal thread.

6. The external cold trap for a dilution refrigerator according to claim 5, characterized in that: The copper mesh filter element (9) is assembled in the compactor seat (16), and the copper mesh filter element (9) is screwed into the compactor seat (16) and compacted on the sealing top cover (13); The compactor (8) is a section of circular tube, half of the cross section of the compactor (8) channel is hexagonal, and the other half is circular, and a portion of the length of the exterior of the circular tube corresponding to the compactor (8) is provided with threads.

7. A method for manufacturing the external cold trap for a dilution refrigerator according to any one of claims 1 to 6, characterized in that: The specific steps are as follows: S1: The liquid nitrogen tank (1) is made of a material with low thermal conductivity, the lower end surface is ground flat, and the upper end surface is provided with an assembly opening (11). The diameter of the assembly opening (11) is larger than the diameter of the lower part (17) of the purification chamber and smaller than the diameter of the sealing top cover (13). The assembly opening (11) is provided with a semicircular vent (12) for nitrogen pressure relief. S2: A high-pressure pipeline through hole (14) and a low-pressure pipeline through hole (15) are left on the sealing top cover (13). A compression seat (16) is welded on the bottom surface of the sealing top cover (13) which is concentric with the low-pressure pipeline through hole (15). The compression seat (16) is a section of circular tube with internal threads. A maintenance channel (10) is left at the center of the sealing top cover (13); S3: The lower part (17) of the purification chamber is used to place the pre-cooling unit (3). The diameter of the pre-cooling unit (3) is larger than the inner diameter of the lower part (17) of the purification chamber, so that the pre-cooling unit (3) and the purification chamber (2) are interference-fitted. A passage for passing through the air inlet pipe (6) is left on the pre-cooling unit (3). The lower part (17) of the purification chamber is used to place the purification unit (4). The purification unit (4) is located above the pre-cooling unit (3) and is made of activated carbon. After the pre-cooled gas flows through the purification unit (4), impurities are removed. S4: The last space is the separation unit (5), which is a cavity used to separate the fine activated carbon particles blown up by the gas; the air inlet pipe (6) is a clean pipe, which passes through the high-pressure pipe through-hole (14) and is airtightly welded to the sealing top cover (13). One end of the air inlet pipe (6) directly reaches the bottom of the lower part (17) of the purification chamber, and a gap is left between the other end face and the upper end face of the sealing top cover (13); S5: The air outlet pipe (7) is welded to the low-pressure pipe through hole (15), with a gap between one end and the upper end surface of the sealing top cover (13), and the other end does not pass through the sealing top cover (13); the copper mesh filter element (9) is assembled in the compressor seat (16), and is screwed into the compressor seat (16) and compressed on the sealing top cover (13); the compressor (8) is a section of circular tube, half of the cross section of the channel is hexagonal, and the other half is circular, and a thread is left on the outer portion of the circular tube.

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