A cryogenic pump and a regeneration control method thereof

Abstract

The present invention provides a cryopump and a regeneration control method thereof. The cryopump includes a cryopump container, a cold shield unit, an adsorption array, a regeneration unit, and a refrigeration unit. The cold shield unit is installed inside the cryopump container, and the adsorption array is composed of an outer condensation shielding plate and an inner cryogenic adsorption plate, and the surface is electroplated and polished. The cooling structure adopts a combination connection method of a main cooling plate and an annular secondary cooling plate to realize the separate disassembly and assembly of the condensation shielding plate and the cryogenic adsorption plate. The regeneration control method monitors the pressure in the container in real time, calculates and processes the pumping speed data. When the pumping speed is lower than the set threshold, the system automatically starts the regeneration process and selects different regeneration strategies (primary, secondary, and complete regeneration) according to the environment and gas type. During the regeneration process, it is determined whether it is completed by temperature data. After the regeneration is completed, the system resumes normal operation and continues to evacuate. The overall process ensures the continued effectiveness and system stability of the cryopump.

Description

Technical Field

[0001] The present invention relates to the field of cryogenic vacuum technology, and in particular to a cryogenic pump and a regeneration control method thereof. Background Art

[0002] A cryopump is a vacuum device that achieves efficient vacuuming through the condensation and adsorption mechanism of a low-temperature surface. It is widely used to create and maintain a high vacuum or ultra-high vacuum environment. Its working principle is to remove gas from the vacuum chamber by condensing or adsorbing gas molecules on a very low temperature surface. For gases with high condensation temperatures (such as water vapor, oxygen, and nitrogen), the cryopump uses a condensation plate to cool the gas molecules to a liquid or solid state for effective removal; for low-boiling point gases that are difficult to condense (such as hydrogen and helium), it relies on activated carbon or porous adsorption materials on the cold surface to adsorb gas molecules on the material surface through van der Waals forces. Cryopumps are widely used in many ultra-high vacuum scenarios, such as wafer processing in semiconductor manufacturing, vacuum cavities of particle accelerators, cryogenic insulation systems of superconducting magnets, and vacuum tests of spacecraft.

[0003] Pumping speed is the core indicator of cryopump performance. It is defined as the volume flow rate of gas removed from the vacuum chamber per unit time, which directly affects the speed of reaching the target vacuum degree and the ability to maintain the vacuum environment. In the fields of semiconductor manufacturing, accelerator physics and superconducting equipment, different gases (such as water vapor, hydrogen and helium) have different requirements for pumping speed, and stable high pumping speed is essential to ensure application accuracy and reliability. Cryopumps are gas capture pumps. Gases are captured by adsorption and condensation respectively. During use, gas frost on the condensation plate will bring additional thermal resistance, reducing the pumping speed of the gas captured by condensation. At the same time, the gas that relies on activated carbon adsorption will also gradually become saturated due to the adsorption of activated carbon, and the pumping speed will decrease. Therefore, it is necessary to judge the change in pumping speed. When the monitored pumping speed drops to the set minimum pumping speed, the connection channel between the vacuum chamber is closed to regenerate the cryopump. However, the pressure sensor monitoring the cryopump in most cases does not directly measure the pressure, but measures the pressure by measuring the change in the interaction between the gas and the sensor. For example, the measurement principle of the Pirani vacuum gauge is the heat conduction of the gas. There is a high-temperature metal wire inside the Pirani vacuum gauge. When the incoming gas molecules enter, they will take away some of the heat on the metal wire, thereby reducing the temperature of the metal wire. The gas pressure is indirectly measured by measuring its temperature change. This measurement method inevitably introduces errors caused by gas type and gas temperature, especially when the use scenario is a wide temperature difference scenario such as a cryogenic pump. The impact of the error cannot be ignored. The measured pressure may fluctuate, and it is no longer possible to accurately judge the regeneration timing by calculating the real-time pumping speed based on the output instant pressure data alone to control the regeneration timing. Summary of the invention

[0004] Based on this, a cryogenic pump and a regeneration control method thereof are proposed.

[0005] Cryogenic pump, including:

[0006] Cryopump container, the external structure of the cryopump, is used to accommodate all internal components and is connected to the vacuum chamber when the cryopump is working to form a closed working environment;

[0007] The cold shield unit is located inside the cryopump container and includes a cold shield inner cylinder and a gas baffle. The cold shield inner cylinder is arranged around the adsorption array to shield external heat radiation and maintain the internal low temperature environment, effectively reducing the influence of environmental heat transfer to the adsorption array. The gas baffle is arranged between the vacuum chamber and the adsorption array to optimize the gas flow path, prevent the gas from directly impacting the cold shield unit, and improve the pumping efficiency of the cryopump. In some embodiments, in order to enhance the pressure bearing capacity of the cold shield inner cylinder, a spoke-type trapezoidal embossed structure is adopted at the bottom of the cold shield inner cylinder, which significantly improves the overall strength and rigidity of the cold shield inner cylinder, can more effectively disperse the pressure, and prevent structural deformation caused by excessive weight load or temperature change. The spoke-type trapezoidal embossed structure not only provides advantages in terms of pressure bearing, but also improves the thermal conductivity characteristics of the cold shield inner cylinder. The embossing increases the gas disturbance near the bottom plate where heat flows, which helps to accelerate heat exchange, thereby improving the heat exchange efficiency of the cold shield inner cylinder and shortening the regeneration time.

[0008] The adsorption array is arranged inside the cold shield unit, and its structure consists of an outer condensation shielding plate and an inner low-temperature adsorption plate. The outer condensation shielding plate is welded by upper and lower annular secondary cold conduction plates and a longitudinal rectangular plate in the middle. The rectangular plates are arranged outward at an angle of 45 degrees, and the outward surfaces are nickel-plated and polished to reduce the absorption of radiant heat from the inner cylinder of the cold shield. Coconut shell activated carbon is evenly pasted on the inner low-temperature adsorption plate as an adsorption medium.

[0009] The roughing valve is set at the bottom of the cryopump container. The cryopump cannot be started under atmospheric pressure. Connect the foreline pump and open the roughing valve. Generally, the cryopump should be started after the foreline vacuum reaches below 10Pa.

[0010] The regeneration unit is used to release the gas adsorbed by the adsorption array and the cold shield unit to restore the pumping capacity of the cryopump. The regeneration unit includes a first-level purge valve, a purge pipeline, a second-level purge valve, a first-level heating assembly and a second-level heating assembly. In addition to the regeneration unit, a safety valve is also equipped to complete the regeneration operation of the cryopump. The first-level purge valve and the safety valve are arranged at the bottom of the cryopump container. The purge pipeline includes a first vertical pipe, a horizontal circumferential pipe and a second vertical pipe. The first vertical pipe runs through the atmosphere and the cryopump container. The horizontal circumferential pipe is located between the cryopump container and the cold shield inner cylinder. The horizontal circumferential pipe is perforated at the center of each trapezoidal embossment at the corresponding bottom so that the purged nitrogen can be blown toward the trapezoidal embossment; the second vertical pipe is led out from the end of the horizontal circumferential pipe and extends to the inside of the cold shield inner cylinder. The second-level purge valve is located at the end of the second vertical pipe. The first-level heating assembly is thermally connected to the cold shield inner cylinder, and the high condensation temperature gas (such as water vapor and oxygen) adsorbed by the cold shield unit is released by heating the cold shield unit. The secondary heating component is thermally connected to the adsorption array and is used to heat the adsorption material in the adsorption array and desorb low condensation temperature gases (such as hydrogen and helium). During the regeneration process, the heating component gradually heats up, and cooperates with purging and exhaust to ensure that the gas is completely desorbed. If the gas released by the cryopump regeneration is not removed in time, the pressure in the container will be very high, which may cause an explosion. A safety valve is installed at the bottom of the cryopump container. When the pressure rises abnormally, the excess gas in the cryopump cavity is automatically discharged to avoid damage to the cryopump or other safety hazards due to overpressure.

[0011] The refrigeration unit provides the cooling source for the cryopump, including the primary refrigeration platform and the secondary refrigeration platform. The primary refrigeration platform is thermally connected to the cold shield unit, responsible for cooling the inner cylinder of the cold shield, and providing a low-temperature environment for condensing high-boiling point gases (such as water vapor). The secondary refrigeration platform is thermally connected to the adsorption array, providing a low-temperature environment for adsorbing low-boiling point gases (such as oxygen, nitrogen, and argon).

[0012] In some embodiments, the refrigeration unit of the cryogenic refrigerator adopts a Gifford-McMahon (GM) refrigerator or a pulse tube refrigerator, using helium as the refrigeration medium, which has high efficiency and stability.

[0013] In some embodiments, the first vertical tube may be a stainless steel bellows to reduce conductive heat leakage introduced from 300K.

[0014] In some embodiments, the cryosorption plate is directly thermally connected to the secondary refrigeration platform through the upper main cold plate and the lower main cold plate. The external condensation shield plate is composed of a rectangular plate, which is thermally connected to the upper annular secondary cold plate and the lower annular secondary cold plate, and the upper annular secondary cold plate and the lower annular secondary cold plate are further connected to the upper main cold plate and the lower main cold plate. This design allows the condensation shield plate or the cryosorption plate to be removed as a whole when maintenance or replacement of parts is required. The upper main cold plate and the lower main cold plate are connected by oxygen-free copper tubes to ensure that the temperature is evenly distributed along the axial direction.

[0015] In some embodiments, during the regeneration operation, the purge pipeline is connected to a high-pressure nitrogen bottle. To further improve the purge efficiency, the nitrogen is preheated before entering the purge valve. The nitrogen is purged at a higher temperature, thereby enhancing the gas's heat energy transfer capacity and promoting rapid heating and heat removal of the cold shield. The temperature of the preheated nitrogen can be adjusted according to specific needs to ensure that the gas has enough heat during the purge process to accelerate heat exchange and reduce the cold load on the cold shield surface.

[0016] In some embodiments, the working modes of the primary heating component and the secondary heating component are flexible and adjustable, and can be turned on separately or simultaneously as needed. Specifically, when only the cold shield unit needs to be regenerated, the primary heating component, the primary purge valve and the rough pumping valve can be turned on to heat the cold shield unit to ensure that the condensed gas on the cold shield unit evaporates and is discharged. When only the adsorption array needs to be regenerated, the secondary heating component, the primary purge valve, the secondary purge valve and the rough pumping valve can be turned on to heat the adsorption array and quickly restore the pumping speed of the cryopump. In some application scenarios, it may be necessary to regenerate the cold shield unit and the adsorption array at the same time. In this case, the primary heating component, the secondary heating component, the primary purge valve, the secondary purge valve and the rough pumping valve are turned on at the same time to provide the required heat for the cold shield unit and the adsorption array respectively. The diameter of the second vertical tube is much larger than the aperture of the small hole on the horizontal circumferential tube, ensuring that the gas flow of the purge gas blowing to the adsorption array is greater than the gas flow blowing to the inner cylinder of the cold shield. This flexible heating control method allows the equipment to adjust the heating process according to different working requirements and optimize the regeneration time and energy efficiency.

[0017] In some embodiments, coconut shell activated carbon is evenly adhered to both sides of the low temperature adsorption plate. As a highly efficient adsorption material, coconut shell activated carbon has an excellent pore structure and a large specific surface area, and can effectively adsorb gas molecules and improve the gas processing capacity of the adsorption array. By evenly coating coconut shell activated carbon on both sides of the low temperature adsorption plate, hydrogen, helium and neon with a condensation temperature below 20K can be adsorbed, further reducing the vacuum degree.

[0018] In some embodiments, the design of the gas baffle has two different surface treatments. The two surfaces facing the cold shield unit are treated with black coating to enhance its absorption capacity of thermal radiation and reduce the influence of external thermal radiation on the cold shield unit. At the same time, the two surfaces of the gas baffle facing the vacuum chamber to be evacuated are nickel-plated and polished. This surface treatment can effectively reduce the influence of thermal radiation. Nickel-plated polishing not only has good corrosion resistance, but also can reduce the reflection of radiant heat and reduce the unnecessary heat load caused by the reflection of radiant heat back to the vacuum chamber or the cold shield unit. The conductance probability of the gas baffle affects the pumping speed of the cryopump, and the conductance probability is determined by its geometric shape. The Monte Carlo method can be used to calculate the shape of the optimal geometric configuration with large conductance probability and small heat load, that is, the "human" structure. The conductance probability of this structure is 0.48~0.55, and the radiation absorption ratio (the ratio of the thermal radiation absorbed by the adsorption array to the thermal radiation incident on the gas baffle) is about 2%.

[0019] The two sides of the gas baffle facing the vacuum chamber are nickel-plated and polished, with low emissivity (generally ε≈0.03~0.15), which can effectively reflect the thermal radiation from the vacuum chamber and prevent excess heat from being transferred to the interior of the cryopump, especially the adsorption array, thereby reducing the thermal load of the cryogenic system; the two sides of the gas baffle facing the interior of the cryopump, especially the adsorption array, are painted black. The black coating usually has a high emissivity (generally ε≈0.8~0.95), which can efficiently absorb the radiant heat, prevent the heat from being reflected to the adsorption array, reduce the temperature fluctuation of the adsorption array, and improve its condensation and adsorption performance.

[0020] According to one embodiment of the present invention, a control method for a cryopump is provided. The control method comprises the following steps:

[0021] S1 Container Pressure Measurement and Data Transmission: Use the pressure sensor to monitor the pressure inside the vacuum chamber in real time, and transmit the measured pressure data to the controller to provide basic data support for subsequent pumping speed calculation.

[0022] S2 Pumping speed calculation and smoothing: The controller calculates the actual pumping speed of the cryogenic pump by analyzing the pressure data. In order to improve the stability and accuracy of the pumping speed data, the moving average algorithm is used to smooth the calculation results, reduce the interference of short-term fluctuations, and obtain more reliable pumping speed information.

[0023] S3 Pumping speed comparison and regeneration judgment: Compare the smoothed pumping speed data with the preset minimum pumping speed threshold. If the pumping speed is lower than the minimum threshold, the system determines that the regeneration program needs to be started. The controller immediately sends a signal to close the valve connected to the vacuum chamber, stop the operation of the refrigerator, and enter the regeneration preparation state.

[0024] S4 Select regeneration mode: According to the use environment of the cryopump and the characteristics of the adsorbed gas, select the appropriate regeneration mode to optimize the regeneration efficiency:

[0025] First-stage regeneration: Open the first-stage heating component, the first-stage purge valve and the rough extraction valve to heat the cold screen unit, which is suitable for the regeneration of captured gas in a higher temperature range;

[0026] Secondary regeneration: Turn on the secondary heating component, primary purge valve, secondary purge valve and roughing valve to regenerate the captured gas in a lower temperature range;

[0027] Complete regeneration: Open the primary heating component and the secondary heating component, the primary purge valve, the secondary purge valve and the rough extraction valve at the same time to completely remove the captured gas. It is suitable for situations with a large number of gas types.

[0028] S5 temperature monitoring and regeneration completion judgment: During the regeneration process, the temperature of the components is monitored by the temperature sensor to ensure that the regeneration reaches the expected target:

[0029] For the first-stage regeneration, when the reading of the first-stage temperature sensor reaches 310K, the regeneration is judged to be complete;

[0030] For secondary regeneration, regeneration is considered complete when the secondary temperature sensor reading reaches 140K;

[0031] For full regeneration, regeneration is considered complete when the primary temperature sensor reading reaches 310K and the secondary temperature sensor reading reaches 140K.

[0032] S6: Cooling down and recovery operation after regeneration: After regeneration is completed, close the first and second heating components, the first purge valve, and the second purge valve. Start the roughing valve, and when the current pressure drops to 10Pa, start the refrigerator to cool down. When the first temperature sensor drops below 70K and the second temperature sensor drops below 14K, the controller opens the valve between the vacuum chamber, and the cryopump resumes normal operation and continues to pump out air.

[0033] This method achieves efficient regeneration and temperature management of the cryopump through automated monitoring and control processes, ensuring the performance stability and reliability of the equipment in long-term operation. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] The present invention will be more readily understood from the detailed description of exemplary embodiments set forth below considered in conjunction with the accompanying drawings, in which:

[0035] Figure 1 is a schematic diagram of a cryopump of the present invention;

[0036] Figure 2 It is the structural diagram of the adsorption array of the present invention;

[0037] Figure 3 This is a diagram of the embossed structure of the bottom of the cold shield inner tube of the present invention;

[0038] Figure 4 It is the working flow chart of the controller of the present invention.

[0039] In the figure: 110-cryogenic pump container, 120-cold shield unit, 121-cold shield inner cylinder, 122-gas baffle, 130-adsorption array, 131-condensation shield plate, 132-cryogenic adsorption plate, 140-regeneration unit, 141-first-stage purge valve, 142-purge pipeline, 143-first-stage heating assembly, 144-second-stage heating assembly, 145-second-stage purge valve, 31-first vertical pipe, 32-second vertical pipe, 33-horizontal circumferential pipe, 1 50-refrigeration unit, 151-secondary refrigeration platform, 152-primary refrigeration platform, 160-pressure sensor, 171-secondary temperature sensor, 172-primary temperature sensor, 180-roughing valve, 210-safety valve, 220-controller, 230-main cooling plate, 231-upper main cooling plate, 232-lower main cooling plate, 240-annular secondary cooling plate, 241-upper annular secondary cooling plate, 242-lower annular secondary cooling plate. DETAILED DESCRIPTION

[0040] The present invention is further described below in conjunction with the accompanying drawings and specific embodiments.

[0041] See also Figure 1 An embodiment of the present invention provides a cryogenic pump. The technical solution and implementation process of the present invention are described in detail below through a specific embodiment.

[0042] The cryopump structure of the present invention mainly includes several core parts such as cryopump container 110, cold shield unit 120, adsorption array 130, regeneration unit 140, refrigeration unit 150, etc. The cryopump container 110 is the external frame of the entire cryopump, which is installed in the vacuum chamber of ion implantation device, sputtering device, evaporation device or other vacuum processing device when in use, and the vacuum degree inside the vacuum chamber is increased to the high vacuum degree required for production, such as 10 -5 -10 -8 Pa. The cold shield unit 120 is installed in the inner cavity of the cryopump container, including a cold shield inner cylinder 121 and a gas baffle 122. Its main function is to isolate the heat radiation from the external environment and maintain the internal low temperature environment through heat exchange with the refrigeration unit 150. At the same time, some gases with higher condensation temperatures will condense and adsorb on the cold shield unit 120.

[0043] The adsorption array 130 is arranged inside the cold shield unit 120, see Figure 2, consisting of an outer condensation shielding plate 131 and an inner cryogenic adsorption plate 132, wherein the outer condensation shielding plate 131 is composed of 20 rectangular plates arranged vertically, each rectangular plate tilted outward at an angle of 45°. The outer surface of the condensation shielding plate 131 is nickel-plated and polished to reduce the heat radiation from the cold shield inner cylinder 121. The cryogenic adsorption plate 132 is placed inside the condensation shielding plate 131, thus avoiding its direct exposure to the heat radiation of the cold shield inner cylinder 121. In addition, the cryogenic adsorption plate 132 and the secondary refrigeration platform 151 are heat-connected through the main cold plate 230, and the rectangular plate in the condensation shielding plate 131 is connected to the annular secondary cold plate 240, which is in turn connected to the main cold plate 230. This design allows the condensation shielding plate 131 and the cryogenic adsorption plate 132 to be disassembled and repaired separately when necessary. The upper and lower main cold plates 230 are connected by oxygen-free copper tubes to ensure that the temperature is evenly distributed along the axial direction. The condensation shielding plate 131 prevents the radiant heat of the high-temperature gas from entering the low-temperature adsorption plate 132. At the same time, some gases will condense on the condensation shielding plate 131 after being cooled. Gases that cannot be condensed will pass through the gaps between the condensation shielding plates 131 and enter the low-temperature adsorption plate 132 to be captured by the activated carbon.

[0044] In order to enhance the pressure bearing performance of the bottom plate, the bottom design of the cold shield inner tube 121 adopts a spoke-type trapezoidal embossed structure, see Figure 3 This structure significantly improves the overall strength and rigidity of the base plate, enabling it to distribute pressure more evenly and prevent deformation when subjected to weight loads or temperature fluctuations. The spoke-type trapezoidal embossing not only enhances the pressure-bearing capacity, but also improves the thermal conductivity. The embossed surface design promotes the disturbance of the gas flow in the heat transfer boundary layer at the bottom of the cold shield inner tube 121, thereby accelerating the heat exchange process and further improving the heat exchange efficiency of the cold shield unit 120. During the regeneration process of a large-diameter cryopump, better heat exchange efficiency leads to a shorter regeneration time.

[0045] The refrigeration unit 150 is composed of a primary refrigeration platform 152 and a secondary refrigeration platform 151. The primary refrigeration platform 152 is thermally connected to the cold shield inner tube 121 to reduce the temperature of the cold shield unit 120 to about 80K. The secondary refrigeration platform 151 is connected to the adsorption array 130 to reduce the temperature of the adsorption array to about 10K.

[0046] When using the cryopump, the rough pump valve 180 must be opened first, the front pump must be connected to roughly pump the vacuum degree to below 10Pa, and then the refrigeration unit 150 must be opened to cool the cryopump body. When the temperature drops to the operating temperature, the connection channel between the cryopump and the vacuum chamber can be opened to start evacuating the vacuum chamber. After the cryopump has been running for a long time, the cold shield unit 120 and the adsorption array 130 will reach a saturated state due to the captured gas molecules, affecting the vacuum pump's pumping capacity. At this time, the cryopump needs to be shut down for regeneration to release the gas captured by the adsorption array 130 and the cold shield unit 120 to restore the cryopump's pumping capacity. The regeneration unit 140 includes a primary purge valve 141, a purge pipe 142, a primary heating assembly 143, a secondary heating assembly 144, and a secondary purge valve 145. The purge pipe 142 includes a first vertical pipe 31, a second vertical pipe 32, and a horizontal circumferential pipe 33. The first vertical tube 31 passes through the atmosphere and the interior of the cryopump container 110. The horizontal circumferential tube 33 is arranged in the space between the cryopump container 110 and the cold shield inner tube 121. The tube is perforated at the center of each corresponding trapezoidal embossing at the bottom of the cold shield inner tube 121 to ensure that the purged nitrogen can be blown directly to the trapezoidal embossing. The second vertical tube 32 connects the horizontal circumferential tube 33 and the internal space of the cold shield inner tube 121. The first purge valve 141 is located at the lower part of the cryopump container 110, and the second purge valve 145 is located at the end of the second vertical tube 32. The first vertical tube 31 can use a stainless steel bellows to reduce heat leakage from room temperature.

[0047] The first-stage heating component 143 heats the cold shield unit 120 to release high condensation temperature gas; the second-stage heating component 144 heats the adsorption array 130 to desorb low condensation temperature gas. The regeneration process ensures complete desorption of the gas by gradually heating up, purging and exhausting. The safety valve 210 automatically exhausts air when the pressure is abnormal to prevent damage or explosion of the pump body due to overpressure. The real-time pumping speed can be inferred from the pressure data monitored by the pressure sensor 160. At the same time, the data fluctuations and errors introduced by the measurement principle of the pressure sensor 160 itself in the usage scenario must be considered. The present invention provides such a regeneration control method. Figure 4 The controller workflow diagram is shown in FIG. 2 . The changes in various parameters of the cryopump during operation are transmitted to the controller 220 in real time. By collecting data from the pressure sensor 160, the pressure change rate in the space of the cryopump can be used to calculate the real-time pumping speed. The calculation formula is:

[0048] Cryopump pumping speed (pumping rate) S It can be calculated by the following formula:

[0049]

[0050] in S : Pumping speed of cryogenic pump (unit: L / s)

[0051] V: The volume of the chamber (unit: L)

[0052] P : Real-time pressure (unit: Pa)

[0053] dP / dt : Rate of change of pressure over time (negative values ​​indicate a decrease in pressure)

[0054] Considering the fluctuation of the measurement stability of the pressure sensor 160, the moving average method is introduced to recalculate the pumping speed over a period of time. Moving Average (MA) is a technique that smoothes data and eliminates noise, and is widely used in time series data analysis. It can more accurately analyze the long-term trend of data and make more appropriate decisions. In the pumping speed monitoring of cryogenic pumps, the use of the moving average method can effectively extract the changing rules of equipment performance and determine when regeneration operations are required:

[0055] 1Select Window Size: Select a window size ( N ), that is, how many data points are used before and after each calculation of the average. This is a key parameter. The larger the window size, the more obvious the smoothing effect, but some detailed information will be lost.

[0056] 2 Calculate the moving average: For each data point in a given time range, calculate the moving average around it. N The average of the data points. The formula is:

[0057]

[0058] Where S(i) is the pumping speed data at time point i, and MA(t) is the moving average at time point t.

[0059] Through this processing, more stable and accurate pumping speed data can be obtained, and then compared with the predefined minimum pumping speed S M When the pumping speed is less than the set minimum pumping speed S M , the system will automatically prompt that the cryopump needs to be regenerated, and the refrigeration unit 150 will be turned off. At this time, it can be determined which regeneration strategy to use according to the main gas components of the use environment.

[0060] Regeneration strategy 1: primary regeneration, when the gas to be captured is concentrated on the cold shield unit 120, such as water vapor, oxygen, argon, nitrogen and other gases with a condensation temperature above 20K. At this time, the controller 220 will control the opening of the primary purge valve 141, the primary heating component 143 and the roughing valve 180 to heat and purge the cold shield unit 120, so that the condensed gas evaporates and is discharged from the safety valve 210. When the reading of the primary temperature sensor 172 reaches 310K, it is regarded as a signal that the regeneration is completed. At this time, the controller 220 will close the purge valve 141, the roughing valve 180 and the primary heating component 143.

[0061] Regeneration strategy two: secondary regeneration. When the gas to be captured is concentrated on the adsorption array 130, such as neon, hydrogen, helium and other gases with a condensation temperature below 20K, the controller 220 will control the opening of the secondary heating component 144, the primary purge valve 141, the secondary purge valve 145 and the rough pumping valve 180 to heat the adsorption array 130 to increase its temperature, discharge the gas captured on the condensation shielding plate 131 and the low-temperature adsorption plate 132, and restore the pumping speed capacity. When the reading of the secondary temperature sensor 171 reaches 140K, it is regarded as a signal that the regeneration is completed. At this time, the controller 220 will close the secondary heating component 144, the primary purge valve 141, the secondary purge valve 145 and the rough pumping valve 180.

[0062] Regeneration strategy three: complete regeneration. When the types of gases to be captured are more complex and their condensation temperatures are distributed between 5K and 200K, the controller 220 will control the opening of the first-level heating component 143, the second-level heating component 144, the first-level purge valve 141, the second-level purge valve 145 and the roughing valve 180 to heat and purge the cryopump as a whole and exhaust all the gases in the pump. When the reading of the first-level temperature sensor 172 reaches 310K and the reading of the second-level temperature sensor 171 reaches 140K, it is regarded as a signal that the regeneration is completed. At this time, the controller 220 will close the first-level heating component 143, the second-level heating component 144 and the purge valve 141.

[0063] After all three regeneration strategies, the refrigeration unit 150 needs to be restarted to cool down to the working temperature, and the cooling time is: regeneration strategy 2 < regeneration strategy 1 < regeneration strategy 3. Under some specific working conditions, the regeneration strategy can be reasonably and flexibly selected to shorten the downtime.

[0064] The above is only a preferred embodiment of the present invention, and the protection scope of the present invention is not limited to the above embodiments. All technical solutions under the concept of the present invention belong to the protection scope of the present invention. It should be pointed out that for ordinary technicians in this technical field, some improvements and modifications without departing from the principle of the present invention should also be regarded as the protection scope of the present invention.

Claims

1. A cryogenic pump, characterized in that: include: Cryogenic pump container (110); A cold shield unit (120), comprising a cold shield inner cylinder (121) and a gas baffle (122); An adsorption array (130) comprises an outer condensation shielding plate (131) and an inner low-temperature adsorption plate (132); The regeneration unit (140) comprises a primary purge valve (141), a purge pipeline (142), a primary heating component (143), a secondary heating component (144), and a secondary purge valve (145); A refrigeration unit (150), comprising a primary refrigeration platform (152) and a secondary refrigeration platform (151); A pressure sensor (160) is arranged on the purge pipe (142); A primary temperature sensor (172) is fixed on the cold shield inner cylinder (121), and a secondary temperature sensor (171) is fixed on the lower part of the adsorption array (130); Roughing valve (180), safety valve (210); Controller (220); A main cooling plate (230), comprising an upper main cooling plate (231) and a lower main cooling plate (232); An annular secondary cooling plate (240), comprising an upper annular secondary cooling plate (241) and a lower annular secondary cooling plate (242); The cold shield unit (120) is installed inside the cryopump container (110), and the adsorption array (130) is located inside the cold shield unit (120); the first-level purge valve (141) and the rough extraction valve (180) are arranged at the bottom of the cryopump container (110); the purge pipe (142) is vertically led out from the bottom opening of the cryopump container (110), and is arranged horizontally in a circle and then vertically connected to the internal space of the cryopump; a second-level purge valve (145) is arranged at the end of the purge pipe (142); the first-level heating component (143) is connected to the cold shield inner cylinder (121) by thermal connection, and the second-level heating component (144) is thermally connected to the adsorption array (130); the refrigeration unit (150) is fixed to the bottom of the cryopump container (110) by flange connection, the first-level refrigeration platform (152) is thermally connected to the cold shield unit (120), and the second-level refrigeration platform (151) is thermally connected to the adsorption array (130).

2. A cryopump according to claim 1, characterized in that: The adsorption array (130) adopts a structure in which an outer condensation shielding plate (131) is combined with an inner low-temperature adsorption plate (132); the condensation shielding plate (131) is composed of 20 rectangular plates arranged longitudinally along the circumferential direction and tilted outward at an angle of 45°, and the outwardly tilted surface is nickel-plated and polished to further reduce the heat radiation of the cold shield inner cylinder (121) to the adsorption array (130); the low-temperature adsorption plate (132) is arranged inside the condensation shielding plate (131), thereby avoiding direct reception of heat radiation from the cold shield inner cylinder (121).

3. A cryopump according to claim 1, characterized in that: The low-temperature adsorption plate (132) is directly thermally connected to the secondary refrigeration platform (151) via the main cooling plate (230); the rectangular plate in the external condensation shielding plate (131) is thermally connected to the annular secondary cooling plate (240); the annular secondary cooling plate (240) is further connected to the main cooling plate (230); when parts need to be repaired or replaced, the condensation shielding plate (131) or the low-temperature adsorption plate (132) can be disassembled as a whole; the main cooling plate (230) is connected in the middle with an oxygen-free copper tube so that the temperature is evenly distributed in the axial direction.

4. A cryopump according to claim 1, characterized in that: The cold shield inner tube (121) is installed on the primary refrigeration platform (152) of the refrigeration unit. The bottom plate adopts a spoke-type trapezoidal embossed structure, which improves the overall strength and rigidity of the bottom plate, can stably support the weight of the cold shield inner tube (121) and the gas baffle (122), and withstand mechanical stress and thermal shock in a low-temperature environment, and prevent structural deformation caused by excessive weight load or temperature changes; when the purge gas is introduced, the spoke-type trapezoidal embossing can increase the disturbance of the gas convection heat transfer boundary layer at the bottom of the cold shield inner tube (121), thereby increasing the heat exchange efficiency and reducing the time required for purge for large-diameter cryogenic pumps.

5. A cryopump according to claim 1, characterized in that: The purge pipeline (142) is externally connected to a high-pressure nitrogen bottle. The purge pipeline (142) comprises a first vertical tube (31), a second vertical tube (32) and a horizontal circumferential tube (33), wherein the first vertical tube (31) penetrates the atmosphere and the interior of the cryopump container (110), the horizontal circumferential tube (33) is arranged in the space between the cryopump container (110) and the cold shield inner tube (121), and a hole is punched at the center position of each trapezoidal embossment corresponding to the bottom of the cold shield inner tube (121) so that the purged nitrogen can be blown toward the trapezoidal embossment; the second vertical tube (32) connects the horizontal circumferential tube (33) and the cold shield inner tube (121). ); the first-level purge valve (141) is located at the lower part of the cryogenic pump container (110), and the second-level purge valve (145) is located at the end of the second vertical pipe (32); when the first-level purge valve (141) and the rough extraction valve (180) are opened, and the second-level purge valve (145) is closed, nitrogen gas alone purges the cold shield inner cylinder (121); when the first-level purge valve (141) and the rough extraction valve (180) are opened, and the second-level purge valve (145) is opened, nitrogen gas can purge the cold shield inner cylinder (121) and the adsorption array (130) at the same time; and nitrogen gas can be preheated when entering the first-level purge valve (141) to improve the purge efficiency.

6. A cryopump according to claim 1, characterized in that: The first-level heating component (143) and the second-level heating component (144) can be turned on separately or simultaneously. When only the cold shield unit (120) needs to be regenerated, the first-level heating component (143) is turned on alone. When only the adsorption array (130) needs to be regenerated, the second-level heating component (144) is turned on alone. When the cold shield unit (120) and the adsorption array (130) are regenerated simultaneously, both the first-level heating component (143) and the second-level heating component (144) are turned on.

7. A cryopump according to claim 1, characterized in that: The surface of the gas baffle (122) facing the cold shield unit (120) is blackened, and the surface facing the vacuum chamber that needs to be evacuated is nickel-plated and polished, thereby reducing the impact of heat radiation from the vacuum chamber.

8. A cryopump regeneration control method, wherein the cryopump is a cryopump according to any one of claims 1 to 7, characterized in that: include: S1 The pressure sensor (160) measures the pressure in the container and transmits the data to the controller (220); The S2 controller (220) calculates the pumping speed data according to the pressure change, and then processes the pumping speed data by a moving average method; S3 The controller (220) compares the processed pumping speed with a preset minimum pumping speed. When the pumping speed is less than the minimum pumping speed, it prompts the start of regeneration, closes the valve connection between the vacuum chamber, and stops the refrigerator at the same time; S4 Determine the regeneration type based on the environment used and the main adsorption gas category: First-stage regeneration: open the first-stage heating component (143), the first-stage purge valve (141), and the roughing valve (180); Secondary regeneration: opening the secondary heating assembly (144), the primary purge valve (141), the roughing valve (180) and the secondary purge valve (145); Full regeneration: open the primary heating assembly (143), the secondary heating assembly (144), the primary purge valve (141), the roughing valve (180) and the secondary purge valve (145); S5 monitors the temperature data during regeneration: First-stage regeneration: regeneration is considered complete when the first-stage temperature sensor reaches 310K; Secondary regeneration - regeneration is considered complete when the secondary temperature sensor reaches 140K; Full regeneration - regeneration is complete when the primary temperature sensor reaches 310K and the secondary temperature sensor reaches 140K; S6 Regeneration is completed, the refrigeration unit (150) is turned on, and the cryopump is cooled down. When the first-stage temperature sensor is less than 70K and the second-stage temperature sensor is less than 14K, the connection with the vacuum chamber is opened, the cryopump resumes the pumping speed, and continues to evacuate the cryopump.

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