Low-temperature combined pump based on molecular pump

Abstract

The utility model relates to the field of vacuum acquisition, in particular to a low-temperature combined pump based on a molecular pump, which comprises a vacuum chamber, a cooling tower, a molecular pump set, a first connecting pipe and a second connecting pipe, the vacuum chamber is provided with a containing cavity, the outer wall of the vacuum chamber is provided with an extraction opening, the extraction opening is communicated with the containing cavity, the cooling tower is provided with a cooling cavity, and the molecular pump set is arranged in the cooling cavity. The cooling tower is provided with a feeding port and a discharging port, the feeding port and the discharging port are both communicated with the cooling cavity, the molecular pump set is provided with an air inlet, the extraction opening is communicated with the feeding port through a first connecting pipe, and the discharging port is communicated with the air inlet through a second connecting pipe. The molecular pump set is started to extract air from the vacuum chamber, the air is extracted after passing through the cooling tower, impurities such as water vapor in the air are left in the cooling chamber, the working quality of the molecular pump is improved, and the vacuum chamber can be conveniently pumped to a certain vacuum degree.

Description

Technical Field

[0001] This application relates to the field of vacuum acquisition, and in particular to a cryogenic combined pump based on a molecular pump. Background Art

[0002] A molecular pump is a vacuum pump that uses a high-speed rotating rotor to transfer momentum to gas molecules, enabling them to obtain a directional velocity, thereby being compressed, driven towards the exhaust port, and then pumped away by the fore pump. It is widely used in fields that require high vacuum or ultra-high vacuum environments, such as semiconductor manufacturing, optical manufacturing, materials science, food processing, medical device manufacturing, and research laboratories.

[0003] An accelerator is a device that increases the speed (kinetic energy) of charged particles (such as electrons, protons, α particles, etc.). In a particle accelerator, ultra-high vacuum can ensure that particles are not interfered with by gas molecules during the acceleration and collision processes. To control the normal acceleration of particles in the acceleration tube, the chamber inside the acceleration tube needs to maintain a certain vacuum degree. When the equipment is not used for a long time, outside air may enter the chamber, affecting the acceleration effect. Therefore, before using the equipment, the air inside the chamber needs to be exhausted. However, conventional molecular pump sets cannot meet the vacuum degree requirements of some accelerators. Summary of the Utility Model

[0004] In order to improve the vacuum degree of the chamber, this application provides a cryogenic combined pump based on a molecular pump.

[0005] The cryogenic combined pump based on a molecular pump provided by this application adopts the following technical solutions:

[0006] A cryogenic combined pump based on a molecular pump includes a vacuum chamber, a cooling tower, a molecular pump set, a first connecting pipe, and a second connecting pipe. The vacuum chamber is provided with a receiving cavity, and an air extraction port is provided on the outer wall of the vacuum chamber. The air extraction port communicates with the receiving cavity. The cooling tower is provided with a cooling cavity, and a feed port and a discharge port are provided on the cooling tower. Both the feed port and the discharge port communicate with the cooling cavity. The molecular pump set is provided with an air inlet. The air extraction port is connected to the feed port through the first connecting pipe, and the discharge port is connected to the air inlet through the second connecting pipe.

[0007] By adopting the above technical solutions, the molecular pump set starts to pump air from the vacuum chamber, and the gas is extracted after passing through the cooling tower. Impurities such as water vapor in the gas remain in the cooling cavity, improving the working quality of the molecular pump and facilitating the pumping of the vacuum chamber to a certain vacuum degree.

[0008] Preferably, it further includes a Dewar flask. The Dewar flask is provided with a heat preservation cavity, and an installation port is provided at one end of the Dewar flask. The installation port communicates with the heat preservation cavity. The cooling tower is connected to the inner wall of the installation port. The heat preservation cavity is used to place a coolant, and the coolant is set as liquid nitrogen.

[0009] By adopting the above technical solution, the coolant is placed in the Dewar flask, which can well insulate the coolant, making it easier for the coolant to cool the cooling tower. The cost of liquid nitrogen is low, and there is no need to purchase expensive cryogenic pumps, and there is no need for expensive cryogenic pump operation and maintenance costs. Under the conditions of limited funds and time, the vacuum quality can be improved.

[0010] Preferably, the cooling tower includes a cooling cylinder, a feed pipe and a discharge pipe, the opening of the installation port faces upward, the cooling cylinder is connected to the inner wall of the installation port, the cooling cylinder is provided with a cooling cavity, the upper end of the cooling cylinder is provided with a feed port and a discharge port, the feed pipe is coaxially fixedly connected to the inner wall of the feed port, the discharge pipe is coaxially fixedly connected to the inner wall of the discharge port, the distance from the feed pipe to the bottom wall of the cooling cavity is smaller than the distance from the discharge pipe to the bottom wall of the cooling cavity, the first connecting pipe is coaxially fixedly connected to the feed pipe, and the second connecting pipe is coaxially fixedly connected to the discharge pipe.

[0011] By adopting the above technical solution, the gas enters the cooling chamber from the feed pipe and is then discharged from the discharge port, which is convenient for cooling the gas before discharging it, and is convenient for handling impurities in the gas, thereby improving the working quality of the molecular pump group and the vacuum degree of the vacuum chamber.

[0012] Preferably, it further comprises a heat conducting block, one end of which is fixedly connected to the outer wall of the feed pipe, and the other end of which is fixedly connected to the inner wall of the cooling chamber.

[0013] By adopting the above technical solution, it is convenient for the gas passing through the feed pipe to exchange heat with the coolant in the heat preservation chamber, thereby improving the cooling efficiency.

[0014] Preferably, the cooling cylinder comprises a cylinder body and a cover plate, the cylinder body is detachably connected to the inner wall of the installation port, a disassembly port is provided at the lower end of the cylinder body, the cover plate is detachably connected to the lower end of the cylinder body, and the cover plate is used to cover the disassembly port.

[0015] By adopting the above technical solution, the cooling cylinder and the Dewar flask are detachably connected, which is convenient for cleaning the Dewar flask, and the cylinder body and the cover plate are detachably connected, which is convenient for cleaning impurities in the cooling cavity and facilitating repeated use of the device.

[0016] Preferably, it also includes a sealing component, which includes a sealing airbag, a spring and an extrusion block. The outer wall of the cylinder is coaxially provided with a sealing ring groove, the sealing airbag is embedded in the sealing ring groove, the inner wall of the mounting port is provided with a mounting groove, one end of the spring is fixedly connected to the bottom of the mounting groove, and the other end of the spring is fixedly connected to the extrusion block, the extrusion block is used to be embedded in the sealing ring groove and extrude the sealing airbag, the end of the extrusion block facing away from the spring is set to a spherical surface, the top wall of the insulation chamber is provided with a connecting groove, the connecting groove is connected to the mounting groove, and the coolant is set to liquid nitrogen.

[0017] By adopting the above technical solution, the cylinder body slides into the heat preservation cavity from the installation opening, the extrusion block is embedded into the sealing ring groove to extrude the sealing airbag, and the sealing airbag seals between the cylinder body and the Dewar bottle. The gasification of liquid nitrogen makes the air pressure in the Dewar bottle greater than the atmospheric pressure, and the extrusion block further slides into the sealing ring groove to tightly press against the sealing airbag, enhancing the sealing performance. The aspherical surface of the extrusion block extends into the sealing ring groove, making it impossible for the cylinder body to be detached from the Dewar bottle, thus completing the relative fixation between the cylinder body and the Dewar bottle. After the pressure in the Dewar bottle is relieved, the extrusion block moves, and the spherical surface makes it convenient for the cylinder body to be detached from the installation opening, facilitating the cleaning of the Dewar bottle and the cooling tower.

[0018] Preferably, the sealing assembly further includes a sealing ring. A sealing groove is provided on the outer wall of the extrusion block, and the sealing ring is embedded in the sealing groove, and the outer wall of the sealing ring abuts against the groove wall of the installation groove.

[0019] By adopting the above technical solution, the sealing ring enhances the sealing performance between the extrusion block and the groove wall of the installation groove, reduces the nitrogen overflow, and reduces the waste of resources.

[0020] Preferably, it further includes a circulation assembly. The circulation assembly includes a liquid storage tank, a liquid nitrogen pump, a third connecting pipe, a fourth connecting pipe, a condenser, a first valve, and a pressure relief valve. The Dewar bottle is provided with a liquid inlet and a pressure relief port, and both the liquid inlet and the pressure relief port communicate with the heat preservation cavity. The outlet of the liquid storage tank communicates with the inlet of the liquid nitrogen pump, the outlet of the liquid nitrogen pump is connected to the liquid inlet through the third connecting pipe, the pressure relief port is connected to the inlet of the condenser through the fourth connecting pipe, the outlet of the condenser is connected to the inlet of the liquid storage tank, the first valve is connected to the inner wall of the third connecting pipe, and the first valve is used to control the on-off of the third connecting pipe. The pressure relief valve is connected to the inner wall of the fourth connecting pipe.

[0021] By adopting the above technical solution, the pressure relief valve adjusts the air pressure in the heat preservation cavity to prevent safety accidents caused by excessive air pressure. The circulation assembly facilitates the control of the recycling of liquid nitrogen and reduces the waste of liquid nitrogen resources.

[0022] Preferably, it further includes a mechanical pump, a fifth connecting pipe, a second valve, and a third valve. An exhaust port is provided on the outer wall of the vacuum chamber, and the exhaust port communicates with the accommodation chamber. One end of the fifth connecting pipe is coaxially and fixedly connected to the inner wall of the exhaust port, and the other end of the fifth connecting pipe is coaxially and fixedly connected to the inner wall of the inlet of the mechanical pump. The second valve is connected to the inner wall of the fifth connecting pipe, and the second valve is used to control the on-off of the fifth connecting pipe. The third valve is connected to the inner wall of the first connecting pipe, and the third valve is used to control the on-off of the first connecting pipe.

[0023] By adopting the above technical solution, the mechanical pump first pumps out most of the gas in the vacuum chamber. After the vacuum degree in the vacuum chamber reaches about 10 Pa, the second valve is closed, the third valve is opened, and the molecular pump is started, which is convenient to achieve a better vacuum degree and reduce the deposition of impurities in the cooling tower.

[0024] In summary, the present application includes at least one of the following beneficial technical effects:

[0025] 1. The molecular pump group is started to pump air from the vacuum chamber. The gas is pumped out after passing through the cooling tower, and impurities such as water vapor in the gas remain in the cooling chamber, improving the working quality of the molecular pump and facilitating the pumping of the vacuum chamber to a certain vacuum degree.

[0026] 2. The cylinder body slides into the heat preservation chamber from the installation opening, and the extrusion block is embedded in the sealing ring groove to squeeze the sealing airbag. The sealing airbag seals between the cylinder body and the Dewar bottle. The gasification of liquid nitrogen makes the air pressure in the Dewar bottle greater than the atmospheric pressure, and the extrusion block further slides into the sealing ring groove to press against the sealing airbag, enhancing the sealing performance. The aspherical surface of the extrusion block extends into the sealing ring groove, making it impossible for the cylinder body to break away from the Dewar bottle, completing the relative fixation of the cylinder body and the Dewar bottle. After the pressure in the Dewar bottle is relieved, the extrusion block moves, and the spherical surface makes it convenient for the cylinder body to be taken out from the installation opening, facilitating the cleaning of the Dewar bottle and the cooling tower.

[0027] 3. The mechanical pump first pumps out most of the gas in the vacuum chamber. After the vacuum degree in the vacuum chamber reaches about 10 Pa, the second valve is closed, the third valve is opened, and the molecular pump is started, facilitating the achievement of a better vacuum degree and reducing the deposition of impurities in the cooling tower. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 is a schematic diagram of the overall structure of a cryogenic combined pump based on a molecular pump.

[0029] Figure 2 is a cross-sectional view of the Dewar bottle, the cooling tower, and the sealing assembly.

[0030] Figure 3 is a cross-sectional view of a cryogenic combined pump based on a molecular pump.

[0031] Figure 4 is Figure 2 the enlarged view of part A in

[0032] Description of reference numerals: 1. Vacuum chamber; 11. Accommodation chamber; 12. Air extraction port; 13. Exhaust port; 2. Air extraction assembly; 21. Mechanical pump; 22. Fifth connecting pipe; 23. Second valve; 3. Dewar flask; 31. Installation port; 311. Installation groove; 32. Heat preservation chamber; 321. Communication groove; 33. Liquid inlet; 34. Pressure relief port; 4. Circulation assembly; 41. Liquid inlet pipe; 42. Pressure relief pipe; 43. Liquid storage tank; 44. Liquid nitrogen pump; 45. Third connecting pipe; 46. Fourth connecting pipe; 47. Condenser; 48. First valve; 49. Pressure relief valve; 5. Cooling tower; 51. Cooling cylinder; 511. Cylinder body; 5111. Cooling chamber; 5112. Disassembly and assembly port; 5113. Feed inlet; 5114. Discharge outlet; 5115. Heat insulation layer; 5116. Sealing ring groove; 512. Cover plate; 5121. Connecting ring; 5122. Baffle; 513. Sealing gasket; 514. Rotating handle; 52. Feed pipe; 53. Discharge pipe; 54. Heat conducting block; 6. Connecting assembly; 61. First connecting pipe; 62. Third valve; 63. Second connecting pipe; 7. Molecular pump group; 71. Air inlet; 8. Sealing assembly; 81. Sealing airbag; 82. Spring; 83. Extrusion block; 831. Spherical surface; 832. Sealing groove; 84. Sealing ring. Detailed implementation manners

[0033] The following further elaborates on this application in conjunction with the attached Figures 1 - 4 drawings for a more detailed description.

[0034] An embodiment of this application discloses a cryogenic combined pump based on a molecular pump. Referring to Figure 1 and Figure 2 , a cryogenic combined pump based on a molecular pump includes a vacuum chamber 1, an air extraction assembly 2, a Dewar flask 3, a circulation assembly 4, a cooling tower 5, a connecting assembly 6, a molecular pump group 7, and a sealing assembly 8.

[0035] Referring to Figure 3 , the vacuum chamber 1 is provided with an accommodation chamber 11, and the outer wall of the vacuum chamber 1 is provided with an air extraction port 12 and an exhaust port 13, and both the air extraction port 12 and the exhaust port 13 communicate with the accommodation chamber 11.

[0036] The air extraction assembly 2 includes a mechanical pump 21, a fifth connecting pipe 22, and a second valve 23. One end of the second connecting pipe 63 is coaxially and fixedly connected to the inner wall of the exhaust port 13, and the other end of the fifth connecting pipe 22 is fixedly connected to the inner wall of the inlet of the mechanical pump 21. The second valve 23 is connected to the inner wall of the fifth connecting pipe 22. The second valve 23 is used to control the on-off of the fifth connecting pipe 22, and the second valve 23 is set as a ball valve. The mechanical pump 21 is started to extract air from the accommodation chamber 11 to improve the vacuum degree of the vacuum chamber 1.

[0037] Referring to Figure 2, an installation port 31 is coaxially provided at the upper end of the Dewar flask 3. The Dewar flask 3 is provided with a heat preservation cavity 32. The installation port 31 communicates with the heat preservation cavity 32. The diameter of the installation port 31 is smaller than that of the heat preservation cavity 32. The heat preservation cavity 32 is used for placing a coolant, and the coolant is set as liquid nitrogen.

[0038] Referring to Figure 1 and Figure 2 , the coolant can be directly poured into the Dewar flask 3, or the liquid nitrogen circulation can be controlled by the circulation assembly 4. The circulation assembly 4 includes a liquid inlet pipe 41, a pressure relief pipe 42, a liquid storage tank 43, a liquid nitrogen pump 44, a third connecting pipe 45, a fourth connecting pipe 46, a condenser 47, a first valve 48 and a pressure relief valve 49. An inlet port 33 and a pressure relief port 34 are provided at the upper end of the Dewar flask 3. The inlet port 33 and the pressure relief port 34 are provided on the outer periphery of the installation port 31. Both the inlet port 33 and the pressure relief port 34 communicate with the heat preservation cavity 32. The liquid inlet pipe 41 is coaxially and fixedly connected to the inner wall of the inlet port 33. The lower end of the liquid inlet pipe 41 is close to the bottom wall of the heat preservation cavity 32. The pressure relief pipe 42 is coaxially and fixedly connected to the inner wall of the pressure relief port 34. The height of the lower end of the pressure relief pipe 42 is higher than the height of the liquid nitrogen liquid level. Both the liquid inlet pipe 41 and the pressure relief pipe 42 are set as heat-insulating pipes.

[0039] The outlet of the liquid storage tank 43 communicates with the inlet of the liquid nitrogen pump 44. One end of the third connecting pipe 45 is coaxially and fixedly connected to the inner wall of the outlet of the liquid nitrogen pump 44. The other end of the third connecting pipe 45 is coaxially and fixedly connected to the liquid inlet pipe 41. One end of the fourth connecting pipe 46 is coaxially and fixedly connected to the inner wall of the pressure relief port 34. The other end of the fourth connecting pipe 46 is coaxially and fixedly connected to the inner wall of the inlet of the condenser 47. The outlet of the condenser 47 communicates with the inlet of the liquid storage tank 43. The first valve 48 is connected to the inner wall of the third connecting pipe 45. The first valve 48 is used to control the on-off of the third connecting pipe 45. The pressure relief valve 49 is connected to the inner wall of the fourth connecting pipe 46. The pressure relief valve 49 is used to control the on-off of the fourth connecting pipe 46.

[0040] Referring to Figure 2, the cooling tower 5 includes a cooling cylinder 51, a feed pipe 52, a discharge pipe 53 and a heat conducting block 54. The cooling cylinder 51 includes a cylinder body 511, a cover plate 512, a gasket 513 and a rotating handle 514. The cylinder body 511 is detachably connected to the inner wall of the installation opening 31. The cylinder body 511 is provided with a cooling cavity 5111. The lower end of the cylinder body 511 is coaxially provided with a disassembly and assembly opening 5112, and the disassembly and assembly opening 5112 communicates with the cooling cavity 5111. The cover plate 512 includes a connecting ring 5121 and a baffle plate 5122. The connecting ring 5121 is fixedly connected to one side of the baffle plate 5122. The gasket 513 is sleeved on the outer circumference of the connecting ring 5121. The outer wall of the connecting ring 5121 is threadedly connected to the inner wall of the disassembly and assembly opening 5112. One side of the gasket 513 abuts against the lower end of the cylinder body 511, and the other side of the gasket 513 abuts against the baffle plate 5122. The baffle plate 5122 covers the disassembly and assembly opening 5112, and the outer wall of the baffle plate 5122 is coplanar with the outer wall of the cylinder body 511. The rotating handle 514 is fixedly connected to the end of the baffle plate 5122 away from the cylinder body 511.

[0041] The upper end of the cylinder body 511 is provided with a feed inlet 5113 and a discharge outlet 5114. Both the feed inlet 5113 and the discharge outlet 5114 communicate with the cooling cavity 5111. The feed pipe 52 is coaxially and fixedly connected to the inner wall of the feed inlet 5113, and the discharge pipe 53 is coaxially and fixedly connected to the inner wall of the discharge outlet 5114. The distance from the feed pipe 52 to the bottom wall of the cooling cavity 5111 is less than the distance from the discharge pipe 53 to the bottom wall of the cooling cavity 5111. Both the feed pipe 52 and the discharge pipe 53 are provided as heat-insulating pipes. The outer wall of the cylinder body 511 is fixedly connected with a heat-insulating layer 5115, and the heat-insulating layer 5115 is arranged outside the Dewar bottle 3.

[0042] Referring to Figure 2 , one end of the heat conducting block 54 is fixedly connected to the outer wall of the feed pipe 53, and the other end of the heat conducting block 54 is fixedly connected to the inner wall of the cooling cavity 5111. There are multiple heat conducting blocks 54, and the multiple heat conducting blocks 54 are evenly spaced along the axial direction of the feed pipe 53.

[0043] Referring to Figure 3 , the connecting component 6 includes a first connecting pipe 61, a third valve 62 and a second connecting pipe 63. One end of the first connecting pipe 61 is coaxially and fixedly connected to the feed pipe 52, and the other end of the first connecting pipe 61 is coaxially and fixedly connected to the inner wall of the air extraction port 12. The third valve 62 is connected to the inner wall of the first connecting pipe 61, and the third valve 62 is used to control the on-off of the first connecting pipe 61. The molecular pump group 7 is provided with an air inlet 71. One end of the second connecting pipe 63 is coaxially and fixedly connected to the discharge pipe 53, and the other end of the second connecting pipe 63 is coaxially and fixedly connected to the inner wall of the air inlet 71. The molecular pump group 7 is a combination of a molecular pump and a mechanical pump, and the molecular pump group 7 pumps air to further improve the vacuum degree of the vacuum chamber 1.

[0044] Referring to Figure 4The sealing assembly 8 includes a sealing airbag 81, a spring 82, an extrusion block 83 and a sealing ring 84. The outer wall of the cylinder 511 is coaxially provided with a sealing ring groove 5116, and the sealing airbag 81 is embedded in the sealing ring groove 5116. The inner wall of the mounting port 31 is provided with a mounting groove 311. There are four mounting grooves 311. The four mounting grooves 311 are evenly spaced around the axis of the mounting port 31. One end of the spring 82 is fixedly connected to the groove bottom of the mounting groove 311, and the other end of the spring 82 is fixedly connected to the extrusion block 83. The extrusion block 83 is used to be embedded in the sealing ring groove 5116 and squeeze the sealing airbag 81. The end of the extrusion block 83 away from the spring 82 is set as a spherical surface 831. The top wall of the heat preservation chamber 32 is provided with a connecting groove 321. There are four connecting grooves 321. The connecting grooves 321 are arranged one by one corresponding to the mounting grooves 311, and the connecting grooves 321 are connected to the mounting grooves 311. The outer wall of the extrusion block 83 is provided with a sealing groove 832 , which is provided on the side of the spherical surface 831 close to the spring 82 . The sealing ring 84 is embedded in the sealing groove 832 , and the outer wall of the sealing ring 84 abuts against the groove wall of the installation groove 311 .

[0045] The implementation principle of a low-temperature combined pump based on a molecular pump in an embodiment of the present application is as follows: when it is necessary to evacuate the vacuum chamber 1, first try to use the vacuum component 2 to evacuate the accommodating chamber 11 to a certain vacuum degree, then close the second valve 23, open the third valve 62, start the molecular pump group 7, and the gas in the accommodating chamber 11 passes through the first connecting pipe 61, the feed pipe 52, the discharge pipe 53, the second connecting pipe 63 and the molecular pump group 7 in sequence. When the gas passes through the cooling chamber 5111, the impurities in the gas are processed by the low temperature, the circulation component 4 allows the liquid nitrogen to be recycled, and the sealing component 8 enhances the sealing of the cooling cylinder 51 and the Dewar flask 3. At the same time, it makes it difficult for the cooling cylinder 51 to fall out of the Dewar flask 3. After use, the liquid nitrogen is discharged, the cooling cylinder 51 is disassembled, and the Dewar flask 3 and the cooling cylinder 51 are cleaned for the next use.

[0046] The above are all preferred embodiments of the present application, and the protection scope of the present application is not limited thereto. Therefore, any equivalent changes made according to the structure, shape, and principle of the present application should be included in the protection scope of the present application.

Claims

1. A cryogenic combined pump based on a molecular pump, characterized in that: It includes a vacuum chamber (1), a cooling tower (5), a molecular pump set (7), a first connecting pipe (61) and a second connecting pipe (63). The vacuum chamber (1) is provided with a receiving cavity (11), and an air extraction port (12) is provided on the outer wall of the vacuum chamber (1). The air extraction port (12) communicates with the receiving cavity (11). The cooling tower (5) is provided with a cooling cavity (5111), and a feed port (5113) and a discharge port (5114) are provided on the cooling tower (5). Both the feed port (5113) and the discharge port (5114) communicate with the cooling cavity (5111). The molecular pump set (7) is provided with an air inlet (71). The air extraction port (12) communicates with the feed port (5113) through the first connecting pipe (61), and the discharge port (5114) communicates with the air inlet (71) through the second connecting pipe (63).

2. The cryogenic combined pump based on a molecular pump according to claim 1, wherein: It further includes a Dewar flask (3). The Dewar flask (3) is provided with a heat preservation cavity (32). One end of the Dewar flask (3) is provided with a mounting port (31), and the mounting port (31) communicates with the heat preservation cavity (32). The cooling tower (5) is connected to the inner wall of the mounting port (31). The heat preservation cavity (32) is used for placing a coolant, and the coolant is set as liquid nitrogen.

3. The cryogenic combined pump based on a molecular pump according to claim 2, characterized in that: The cooling tower (5) includes a cooling cylinder (51), a feed pipe (52) and a discharge pipe (53). The opening of the mounting port (31) faces upward. The cooling cylinder (51) is connected to the inner wall of the mounting port (31). The cooling cylinder (51) is provided with a cooling cavity (5111). The upper end of the cooling cylinder (51) is provided with a feed port (5113) and a discharge port (5114). The feed pipe (52) is coaxially and fixedly connected to the inner wall of the feed port (5113), and the discharge pipe (53) is coaxially and fixedly connected to the inner wall of the discharge port (5114). The distance from the feed pipe (52) to the bottom wall of the cooling cavity (5111) is less than the distance from the discharge pipe (53) to the bottom wall of the cooling cavity (5111). The first connecting pipe (61) is coaxially and fixedly connected to the feed pipe (52), and the second connecting pipe (63) is coaxially and fixedly connected to the discharge pipe (53).

4. The cryogenic combined pump based on a molecular pump according to claim 3, characterized in that: It further includes a heat conducting block (54). One end of the heat conducting block (54) is fixedly connected to the outer wall of the feed pipe (52), and the other end of the heat conducting block (54) is fixedly connected to the inner wall of the cooling cavity (5111).

5. The cryogenic combined pump based on a molecular pump according to claim 3, wherein: The cooling cylinder (51) includes a cylinder body (511) and a cover plate (512). The cylinder body (511) is detachably connected to the inner wall of the mounting port (31). The lower end of the cylinder body (511) is provided with a disassembly and assembly port (5112). The cover plate (512) is detachably connected to the lower end of the cylinder body (511), and the cover plate (512) is used for covering the disassembly and assembly port (5112).

6. The cryogenic combined pump based on a molecular pump according to claim 5, characterized in that: It further includes a sealing assembly (8), the sealing assembly (8) includes a sealing airbag (81), a spring (82) and a pressing block (83), a sealing ring groove (5116) is coaxially provided on the outer wall of the cylinder body (511), the sealing airbag (81) is embedded in the sealing ring groove (5116), an installation groove (311) is provided on the inner wall of the installation port (31), one end of the spring (82) is fixedly connected to the bottom of the installation groove (311), the other end of the spring (82) is fixedly connected to the pressing block (83), the pressing block (83) is used for being embedded in the sealing ring groove (5116) and pressing the sealing airbag (81), the end of the pressing block (83) facing away from the spring (82) is provided as a spherical surface (831), a communication groove (321) is provided on the top wall of the heat preservation cavity (32), and the communication groove (321) communicates with the installation groove (311).

7. The cryogenic combined pump based on a molecular pump according to claim 6, characterized in that: The sealing assembly (8) further includes a sealing ring (84), a sealing groove (832) is provided on the outer wall of the pressing block (83), the sealing ring (84) is embedded in the sealing groove (832), and the outer wall of the sealing ring (84) abuts against the groove wall of the installation groove (311).

8. The cryogenic combined pump based on a molecular pump according to claim 6, characterized in that: It further includes a circulation assembly (4), the circulation assembly (4) includes a liquid storage tank (43), a liquid nitrogen pump (44), a third connecting pipe (45), a fourth connecting pipe (46), a condenser (47), a first valve (48) and a pressure relief valve (49), the Dewar flask (3) is provided with a liquid inlet (33) and a pressure relief port (34), both the liquid inlet (33) and the pressure relief port (34) communicate with the heat preservation cavity (32), the outlet of the liquid storage tank (43) communicates with the inlet of the liquid nitrogen pump (44), the outlet of the liquid nitrogen pump (44) communicates with the liquid inlet (33) through the third connecting pipe (45), the pressure relief port (34) communicates with the inlet of the condenser (47) through the fourth connecting pipe (46), the outlet of the condenser (47) communicates with the inlet of the liquid storage tank (43), the first valve (48) is connected to the inner wall of the third connecting pipe (45), and the first valve (48) is used for controlling the on-off of the third connecting pipe (45), and the pressure relief valve (49) is connected to the inner wall of the fourth connecting pipe (46).

9. The cryogenic combined pump based on a molecular pump according to claim 1, characterized in that: It further includes a mechanical pump (21), a fifth connecting pipe (22), a second valve (23) and a third valve (62), an exhaust port (13) is provided on the outer wall of the vacuum chamber (1), the exhaust port (13) communicates with the accommodation chamber (11), one end of the fifth connecting pipe (22) is coaxially and fixedly connected to the inner wall of the exhaust port (13), the other end of the fifth connecting pipe (22) is coaxially and fixedly connected to the inner wall of the inlet of the mechanical pump (21), the second valve (23) is connected to the inner wall of the fifth connecting pipe (22), and the second valve (23) is used for controlling the on-off of the fifth connecting pipe (22), and the third valve (62) is connected to the inner wall of the first connecting pipe (61), and the third valve (62) is used for controlling the on-off of the first connecting pipe (61).

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