A cryopump and a gas adsorption method thereof

Abstract

This invention relates to the field of cryogenic pump technology, and more particularly to a cryogenic pump and its gas adsorption method. It includes: a pump casing, internally equipped with an 80K cold shield assembly and a 15K cold umbrella assembly; an 80K baffle disposed at the air inlet end of the pump casing, the gap of which forms a main air inlet channel; the 80K cold shield assembly comprising an upper cold shield and a lower cold shield; the upper cold shield is a cylindrical structure open at both ends, with the top connected to the 80K baffle; the lower cold shield is a bottomed cylinder open at the top and closed at the bottom, fitted onto the lower outer side of the upper cold shield, and its diameter is larger than that of the upper cold shield; an additional gas channel is formed between the outer wall of the upper cold shield and the inner wall of the pump casing; the open end of the lower cold shield communicates with the additional gas channel, and its bottom inner wall forms a bottom rebound guide section; the 15K cold umbrella assembly includes an upper 15K cold umbrella and a lower 15K cold umbrella, respectively forming an upper adsorption region and a lower adsorption region; the purpose of this invention is to solve the problems of low bottom space utilization and limited adsorption capacity in existing cryogenic pumps.

Description

Technical Field

[0001] This invention relates to the field of cryogenic pump technology, and in particular to a cryogenic pump and a gas adsorption method thereof. Background Technology

[0002] Cryogenic pumps, as key components in high-vacuum and ultra-high-vacuum systems, are widely used in fields with stringent cleanliness and vacuum requirements, such as semiconductor manufacturing. Their working principle primarily relies on the condensation and adsorption of gas molecules on a low-temperature surface (typically 10–20 K), while simultaneously using thermal radiation shielding structures around 80 K (such as cold shields and baffles) to reduce interference from ambient heat radiation on the low-temperature adsorption region, thereby maintaining efficient pumping performance. Existing cryogenic pumps typically include a pump casing, a cryocooler, an 80 K-class cold shield assembly, and a 15 K-class cold umbrella assembly.

[0003] However, existing technologies have key limitations that restrict further improvements in the performance of cryogenic pumps. First, the gas flow path of traditional cryogenic pumps is mainly concentrated in the upper and middle parts of the pump body, resulting in low space utilization in the lower section of the cold shield and the pump bottom area. This limits the effective adsorption area, making it difficult to break through the limits of the overall pumping speed and adsorption capacity. Summary of the Invention

[0004] The purpose of this invention is to solve the problems of low utilization rate of bottom space and limited adsorption capacity of existing cryogenic pumps.

[0005] To achieve the above objectives, the present invention adopts the following technical solution: According to a first aspect of the present invention, a cryogenic pump is provided, comprising: The pump housing contains an 80K cold shield assembly and a 15K cold umbrella assembly. An 80K baffle is installed at the air inlet end of the pump casing, and the gap between them forms the main air inlet channel; The 80K cold screen assembly includes an upper cold screen and a lower cold screen; the upper cold screen is a cylindrical structure open at both ends, with the top connected to the 80K baffle; the lower cold screen is a bottomed cylinder open at the top and closed at the bottom, fitted onto the lower outer side of the upper cold screen, and its diameter is larger than that of the upper cold screen. An additional gas channel is formed between the outer wall of the upper section of the cold shield and the inner wall of the pump casing; The open end of the lower section of the cold shield is connected to the additional gas channel, and its bottom inner wall forms a bottom rebound guide section; The 15K cooling umbrella assembly includes an upper 15K cooling umbrella and a lower 15K cooling umbrella, which respectively form an upper adsorption area and a lower adsorption area; The gas can enter the upper part of the pump casing through the main air intake channel and be adsorbed by the upper adsorption area. It can also flow downward through the additional gas channel, enter the pump casing through the open end of the lower section cold screen, and flow upward to the lower adsorption area under the guidance of the bottom rebound guide section to be adsorbed.

[0006] Optionally, the axial length of the upper cold screen is greater than the axial length of the lower cold screen, and the main body of the upper cold screen extends axially to near the bottom of the lower cold screen.

[0007] Optionally, the bottom inner wall of the lower section of the cold shield has a smooth arc transition surface, which is used to bounce the downward flowing gas into an upward flow.

[0008] Optionally, the upper 15K cold umbrella surface of the upper adsorption region and / or the lower 15K cold umbrella surface of the lower adsorption region may be provided with a low-temperature adsorption material layer, wherein the low-temperature adsorption material layer is one or a combination of activated carbon and molecular sieve.

[0009] Optionally, the 80K baffle can be a louvered baffle, a grid baffle, or a multi-plate baffle, used for preliminary cooling of the incoming gas.

[0010] Optionally, the low-temperature adsorption material layer of the upper adsorption region covers the surface of the upper 15K cold umbrella facing the main air intake channel, and the low-temperature adsorption material layer of the lower adsorption region covers the surface of the lower 15K cold umbrella facing the bottom rebound guide.

[0011] Optionally, the upper part of the pump casing is provided with an outwardly protruding flange or mounting connection.

[0012] Optionally, both the 80K baffle and the 80K cold shield assembly are connected to the primary cold head of the refrigerator; the 15K cold umbrella assembly is connected to the secondary cold head of the refrigerator.

[0013] According to a second aspect of the present invention, a gas adsorption method using the above-described cryogenic pump is provided, comprising the following steps: The gas to be pumped enters the cryogenic pump structure from the inlet end of the pump casing and is divided into two paths; One of the gas streams enters the upper part of the pump casing through the 80K baffle and is adsorbed by the upper adsorption area. Another gas path is allowed to enter the additional gas channel formed between the upper cold screen and the inner wall of the pump casing, and flow along the channel toward the bottom of the pump casing; The gas flowing along the additional gas channel enters the pump housing through the open end of the lower cooling screen; The flow direction of the gas is changed by the rebound guide section on the bottom inner wall of the lower section of the cold screen, so that the gas is guided from bottom to top to the lower adsorption area; The introduced gas is adsorbed through the lower adsorption region.

[0014] Optionally, by coordinating the additional gas channel, the open end of the lower cold shield, and the rebound guide, some of the gas to be pumped can bypass the upper adsorption area and be transported to the lower adsorption area, thereby increasing the contact area and contact path between the gas to be pumped and the surface of the lower 15K cold umbrella, and improving the adsorption capacity of the cryogenic pump.

[0015] The advantages of this invention are as follows: Compared with existing cryogenic pumps, by setting up a dual-intake path consisting of a main intake channel and an additional gas channel, some gas is effectively guided to bypass the saturated or heavily loaded upper adsorption area and directly delivered to the underutilized lower 15K cold umbrella adsorption area, which significantly expands the effective adsorption area and improves the overall pumping speed and adsorption capacity. Attached Figure Description

[0016] To more clearly illustrate the technical solutions in the embodiments of the present invention, the accompanying drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0017] Figure 1 This is a schematic diagram of the cryogenic pump described in this invention.

[0018] In the diagram: 1. Pump housing; 2. 80K cold shield assembly; 201. Upper cold shield; 202. Lower cold shield; 3. 15K cold umbrella assembly; 301. Upper 15K cold umbrella; 302. Lower 15K cold umbrella; 4. 80K baffle; 5. Main air intake channel; 6. Additional gas channel; 7. Refrigeration unit; 8. Upper adsorption area; 9. Lower adsorption area. Detailed Implementation

[0019] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0020] Example 1

[0021] like Figure 1As shown, a cryogenic pump includes a pump housing 1, inside which is an 80K cold shield assembly 2 and a 15K cold umbrella assembly 3. An 80K baffle 4 with gaps is provided at the air inlet end of the pump housing 1, forming a main air inlet channel 5. The 80K cold shield assembly 2 consists of an upper cold shield 201 and a lower cold shield 202. The upper cold shield 201 is a cylindrical structure open at both ends, with its top connected to the 80K baffle 4. The lower cold shield 202 is a bottomed cylinder open at the top and closed at the bottom, fitted onto the lower outer side of the upper cold shield 201, and the diameter of the lower cold shield 202 is larger than that of the upper cold shield 201. An additional gas channel 6 is formed between the outer wall of the upper cold shield 201 and the inner wall of the pump housing 1. The open end of the lower cold shield 202 communicates with this additional gas channel 6, and its bottom inner wall forms a bottom rebound guide for rebounding airflow. The 15K cooling umbrella assembly 3 includes an upper 15K cooling umbrella 301 and a lower 15K cooling umbrella 302, forming an upper adsorption region 8 and a lower adsorption region 9, respectively. During operation, part of the gas entering the pump housing 1 enters the upper part of the pump housing directly through the main air intake channel 5 and is adsorbed by the upper adsorption region 8; the other part of the gas flows downward along the additional gas channel 6, enters the pump housing through the open end of the lower cooling screen 202, changes its flow direction under the action of the bottom rebound guide, moves upward and is adsorbed by the lower adsorption region 9.

[0022] The axial length of the upper cold screen 201 is greater than that of the lower cold screen 202, and the main body of the upper cold screen 201 extends axially to near the bottom of the lower cold screen 202, thereby lengthening the path of the gas in the cold screen area and improving the pre-cooling efficiency. The bottom inner wall of the lower cold screen 202 has a smooth arc transition surface, allowing the downward-flowing gas to bounce smoothly and turn upward after impact, avoiding gas stagnation and improving the gas delivery efficiency to the adsorption area. The surface of the upper 15K cold umbrella 301 in the upper adsorption area 8 and the surface of the lower 15K cold umbrella 302 in the lower adsorption area 9 are both covered with a low-temperature adsorption material layer. This material layer uses one or a combination of activated carbon and molecular sieves to enhance the low-temperature capture capability of different types of gas molecules. The 80K baffle 4 adopts a louvered baffle, a grid baffle, or a multi-plate baffle structure to initially cool and shield the incoming gas, reduce the impact of heat radiation on the internal low-temperature components, and initially condense high-boiling-point gas components. The low-temperature adsorption material layer of the upper adsorption region 8 covers the surface of the upper 15K cold umbrella 301 facing the main air intake channel 5, ensuring that the directly entering gas can be efficiently adsorbed; the low-temperature adsorption material layer of the lower adsorption region 9 covers the surface of the lower 15K cold umbrella 302 facing the bottom rebound guide, so as to effectively capture the gas rising after rebound guide. The pump casing 1 is provided with an outwardly protruding flange or mounting connection part for easy and reliable connection with other equipment. The 80K baffle 4 and the 80K cold shield assembly 2 are both connected to the first-stage cold head of the refrigerator 7, maintaining an operating temperature of about 80K; the 15K cold umbrella assembly 3 is connected to the second-stage cold head of the refrigerator 7, maintaining a low temperature of about 15K, thereby realizing staged cooling and efficient adsorption of the gas.

[0023] In a preferred embodiment, the axial length of the upper cold shield 201 is eight times the axial length of the lower cold shield 202, and the distance between its lower end and the bottom of the lower cold shield 202 does not exceed 5 mm, in order to optimize the gas flow path and thermal shielding effect. In a preferred embodiment, the low-temperature adsorption material layer contains both activated carbon and molecular sieves, which synergistically improve the overall gas extraction performance. In a preferred embodiment, the 80K baffle 4 uses multiple parallel plate-shaped baffles with a spacing of 3 mm between adjacent baffles, which can effectively block heat radiation without hindering gas flow. In a preferred embodiment, the adsorption surfaces of the upper 15K cold umbrella 301 and the lower 15K cold umbrella 302 are treated with plasma spraying, so that the low-temperature adsorption material layer is firmly attached and has a high specific surface area. In a preferred embodiment, the refrigerator 7 is a two-stage Gifford-McMahon refrigerator 7. The output power of the first-stage cold head is sufficient to maintain the stable operation of the 80K baffle 4 and the 80K cold shield assembly 2, and the second-stage cold head provides sufficient cooling to allow the 15K cold umbrella assembly 3 to reach the design adsorption temperature.

[0024] Example 2

[0025] A gas adsorption method employing a cryogenic pump structure includes the following steps: The gas to be pumped enters the cryogenic pump structure from the inlet end of the pump casing 1 and is divided into two paths; One of the gas streams enters the upper part of the pump casing through the 80K baffle 4 and is adsorbed by the upper adsorption region 8. Another gas path is allowed to enter the additional gas channel 6 formed between the upper section of the cold screen 201 and the inner wall of the pump housing 1, and flow along the channel toward the bottom of the pump housing 1; The gas flowing along the additional gas channel 6 enters the pump casing through the open end of the lower section cold screen 202; The flow direction of the gas is changed by the rebound guide part on the bottom inner wall of the lower section cold screen 202, and the gas is guided from bottom to top to the lower adsorption area 9; The introduced gas is adsorbed through the lower adsorption region 9.

[0026] The cryogenic pump structure used in this method has been described in detail in Example 1, including the pump housing 1, 80K cold shield assembly 2, 15K cold umbrella assembly 3, 80K baffle 4, main air intake channel 5, additional gas channel 6, bottom rebound guide part, upper and lower adsorption areas 9, etc., as well as the structural relationship, material configuration and refrigeration connection method of each component, which will not be repeated here.

[0027] Through the combined effect of the additional gas channel 6, the open end of the lower section cold shield 202, and the rebound guide section, some of the gas to be pumped bypasses the upper adsorption region 8 and is guided to the lower adsorption region 9, effectively improving the overall adsorption capacity of the cryogenic pump.

[0028] In a preferred embodiment, the axial length of the upper section of the cold screen 201 is 8 times the axial length of the lower section of the cold screen 202, and its lower end is no more than 5 mm away from the bottom of the lower section of the cold screen 202, so as to optimize the gas diversion path and enhance the pre-cooling effect.

[0029] In a preferred embodiment, the upper 15K cold umbrella 301 surface of the upper adsorption region 8 and the lower 15K cold umbrella 302 surface of the lower adsorption region 9 are both covered with a composite low-temperature adsorption material layer composed of activated carbon and molecular sieves, which synergistically enhance the overall gas extraction capacity of the mixed gas.

[0030] In a preferred embodiment, the 80K baffle 4 uses multiple parallel plate-shaped baffles with a spacing of 3 mm between adjacent baffles, which can achieve effective heat shielding while ensuring smooth gas flow.

[0031] In a preferred embodiment, the adsorption surfaces of the upper 15K cold umbrella 301 and the lower 15K cold umbrella 302 are both treated with plasma spraying to ensure that the low-temperature adsorption material layer is firmly attached and has a high specific surface area, thereby improving adsorption efficiency and service life.

[0032] In a preferred embodiment, the refrigerator 7 is a two-stage Gifford-McMahon refrigerator 7. The first-stage cold head maintains the 80K baffle 4 and the 80K cold shield assembly 2 at a temperature of about 80K, while the second-stage cold head enables the 15K cold umbrella assembly 3 to operate stably at about 15K, thereby achieving staged cooling and efficient capture of the gas.

[0033] The above description is merely a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in the present invention should be included within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the scope of the claims.

Claims

1. A cryogenic pump, characterized in that, include: The pump housing contains an 80K cold shield assembly and a 15K cold umbrella assembly. An 80K baffle is installed at the air inlet end of the pump casing, and the gap between them forms the main air inlet channel; The 80K cold screen assembly includes an upper cold screen and a lower cold screen; the upper cold screen is a cylindrical structure open at both ends, with the top connected to the 80K baffle; the lower cold screen is a bottomed cylinder open at the top and closed at the bottom, fitted onto the lower outer side of the upper cold screen, and its diameter is larger than that of the upper cold screen. An additional gas channel is formed between the outer wall of the upper section of the cold shield and the inner wall of the pump casing; The open end of the lower section of the cold shield is connected to the additional gas channel, and its bottom inner wall forms a bottom rebound guide section; The 15K cooling umbrella assembly includes an upper 15K cooling umbrella and a lower 15K cooling umbrella, which respectively form an upper adsorption area and a lower adsorption area; The gas can enter the upper part of the pump casing through the main air intake channel and be adsorbed by the upper adsorption area. It can also flow downward through the additional gas channel, enter the pump casing through the open end of the lower section cold screen, and flow upward to the lower adsorption area under the guidance of the bottom rebound guide section to be adsorbed.

2. The cryogenic pump according to claim 1, characterized in that: The axial length of the upper cold screen is greater than the axial length of the lower cold screen, and the main body of the upper cold screen extends axially to near the bottom of the lower cold screen.

3. The cryogenic pump according to claim 1, characterized in that: The bottom inner wall of the lower section of the cold shield has a smooth arc transition surface, which is used to bounce the downward flowing gas into an upward flow.

4. The cryogenic pump according to claim 1, characterized in that: The upper 15K cooling umbrella surface of the upper adsorption region and / or the lower 15K cooling umbrella surface of the lower adsorption region are provided with a low-temperature adsorption material layer, wherein the low-temperature adsorption material layer is one or a combination of activated carbon and molecular sieve.

5. The cryogenic pump according to claim 1, characterized in that: The 80K baffle is a louvered baffle, a grid baffle, or a multi-plate baffle, used for preliminary cooling of the incoming gas.

6. The cryogenic pump according to claim 1, characterized in that: The low-temperature adsorption material layer of the upper adsorption region covers the surface of the upper 15K cold umbrella facing the main air intake channel, and the low-temperature adsorption material layer of the lower adsorption region covers the surface of the lower 15K cold umbrella facing the bottom rebound guide.

7. The cryogenic pump according to claim 1, characterized in that: The upper part of the pump casing is provided with an outwardly protruding flange or mounting connection.

8. The cryogenic pump according to claim 1, characterized in that: Both the 80K baffle and the 80K cold shield assembly are connected to the primary cold head of the refrigerator; the 15K cold umbrella assembly is connected to the secondary cold head of the refrigerator.

9. A gas adsorption method using a cryogenic pump according to any one of claims 1 to 8, characterized in that, Includes the following steps: The gas to be pumped enters the cryogenic pump structure from the inlet end of the pump casing and is divided into two paths; One of the gas streams enters the upper part of the pump casing through the 80K baffle and is adsorbed by the upper adsorption area. Another gas path is allowed to enter the additional gas channel formed between the upper cold screen and the inner wall of the pump casing, and flow along the channel toward the bottom of the pump casing; The gas flowing along the additional gas channel enters the pump housing through the open end of the lower cooling screen; The flow direction of the gas is changed by the rebound guide section on the bottom inner wall of the lower section of the cold screen, so that the gas is guided from bottom to top to the lower adsorption area; The introduced gas is adsorbed through the lower adsorption region.

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