Expanded low-temperature vacuum pump

Abstract

The invention discloses an expanded low-temperature vacuum pump which comprises a cover body, anti-radiation screens arranged in the cover body at intervals, baffles arranged at the tops of the anti-radiation screens and a refrigerating machine installed on the side face of the cover body. The middle part of the anti-radiation screen extends outwards to form a convex anti-radiation screen annular part; a plurality of through holes are formed in the baffle, and gas enters the radiation-proof screen from the through holes; the refrigerating machine extends into the anti-radiation screen, a plurality of condensation plates are horizontally arranged at the tail end of the refrigerating machine, and the first condensation plate located at the top is arranged in the annular part of the anti-radiation screen; the space between the upper surface of the first condensation plate and the annular part of the anti-radiation screen is a reserved condensation layer, and the thickness of the reserved condensation layer is more than half of the height of the annular part of the anti-radiation screen. The exhaust volume limit of the low-temperature vacuum pump can be improved.

Description

Technical Field

[0001] The invention relates to a cryogenic vacuum pump, in particular to an enlarged cryogenic vacuum pump. Background Art

[0002] A cryogenic vacuum pump is a vacuum pump that uses an ultra-low temperature cryopanel and activated carbon attached to the cryopanel to condense or adsorb gas. In this way, the cryogenic vacuum pump evacuates the chamber connected to the cryogenic vacuum pump.

[0003] The cryogenic vacuum pump is equipped with a refrigerator, a cover, a radiation shield, a baffle, and a cryogenic plate located inside the radiation shield. The radiation shield is cylindrical and surrounded by the cover, and the baffle with an air flow channel is fixed to the upper end of the radiation shield. The main components of the refrigerator are surrounded by the cover. The cryogenic plate includes a plurality of condensation plate components arranged from top to bottom, and the cryogenic plate is thermally connected to the cooling component of the refrigerator, and the temperature of the cryogenic plate is reduced to, for example, 10-15K. The gas enters the interior of the cryogenic vacuum pump through the baffle air flow channel, and most of the gas contacts the topmost condensation plate and is condensed. When the gas condensation layer on the topmost condensation plate grows to a certain thickness, the temperature of the condensation layer will rise, and the gas contacting the surface of the condensation layer cannot be condensed, that is, the ability of the cryogenic vacuum pump to condense the gas decreases, which is manifested as an increase in the internal pressure of the cryogenic vacuum pump. At this time, the amount of gas introduced is the vacuum capacity limit of the cryogenic vacuum pump. Summary of the invention

[0004] Purpose of the invention: The purpose of the present invention is to provide an enlarged cryogenic vacuum pump capable of improving the exhaust capacity limit of the cryogenic vacuum pump.

[0005] Technical solution: An enlarged low-temperature vacuum pump of the present invention includes a cover body, a radiation shield arranged inside the cover body at intervals, a baffle arranged on the top of the radiation shield, and a refrigerator installed on the side of the cover body; the middle part of the radiation shield extends outward to form a protruding annular part of the radiation shield; a plurality of through holes are opened on the baffle, and the gas enters the interior of the radiation shield from the plurality of through holes; the refrigerator extends into the interior of the radiation shield, and a plurality of condensation plates are horizontally arranged at the end of the refrigerator, wherein the first condensation plate at the top is placed inside the annular part of the radiation shield; the space between the upper surface of the first condensation plate and the annular part of the radiation shield is a reserved condensation layer, and the thickness of the reserved condensation layer is more than half of the height of the annular part of the radiation shield.

[0006] Furthermore, the cover body includes an upper cover body portion and a lower cover body portion, and the upper cover body portion and the lower cover body portion are fixedly connected via a cover body flange to achieve overall installation and fixation of the cover body.

[0007] Furthermore, the cover flange includes an upper cover flange portion and a lower cover flange portion, and the two are fastened together by bolts and nuts to achieve installation and fixation of the cover flange.

[0008] Furthermore, the bottom of the upper part of the cover body extends outward to form an annular upper part of the cover body, the top of the lower part of the cover body extends outward to form an annular lower part of the cover body, and the annular upper part of the cover body and the annular lower part of the cover body are spliced ​​to form an annular part of the cover body, which is used to accommodate the annular part of the radiation protection screen; the height of the annular part of the radiation protection screen is more than 85% of the height of the annular part of the cover body, so that the height of the annular part of the radiation protection screen can be expanded to the greatest extent, thereby increasing the reserved condensation layer thickness, which helps to improve the vacuum capacity limit of the low-temperature vacuum pump.

[0009] Furthermore, the reserved condensation layer thickness is more than 85% of the height of the annular portion of the radiation shield, thereby maximizing the exhaust capacity limit of the cryogenic vacuum pump.

[0010] Furthermore, the radius of the first condensation plate is larger than the radius of the radiation protection screen and smaller than the radius of the annular portion of the radiation protection screen, thereby increasing the size of the first condensation plate and thus expanding the size of the condensation layer on the upper surface of the first condensation plate.

[0011] Furthermore, a second condensation plate and a third condensation plate are arranged in the radiation protection screen below the first condensation plate. The second condensation plate and the third condensation plate are arranged horizontally at intervals, and the gas that cannot be condensed by the first condensation plate is condensed by the second condensation plate or the third condensation plate during the descent process.

[0012] Furthermore, the refrigerator includes a first cylinder, a primary cooling stage arranged at the output end of the first cylinder, a second cylinder arranged at the end of the primary cooling stage, and a secondary cooling stage arranged at the output end of the second cylinder; wherein the primary cooling stage is also connected to an anti-radiation screen, and the secondary cooling stage is also connected to a plurality of condensation plates to achieve different degrees of condensation on the anti-radiation screen and the condensation plates.

[0013] Furthermore, the radiation shield is cooled to a temperature within the range of 80 to 100 K, and the plurality of condensation plates are cooled to a temperature within the range of 10 to 20 K, so that the condensation effect is better.

[0014] Furthermore, the multiple condensation plates are fixedly mounted on a connecting plate, the connecting plate is thermally connected to a secondary cooling stage, and the secondary cooling stage can cool down the multiple condensation plates simultaneously.

[0015] Beneficial effects: Compared with the prior art, the significant technical effects of the present invention are as follows:

[0016] The present invention arranges the cryogenic vacuum pump cover into two parts, the upper part and the lower part of the cover, and enlarges the diameter of the flange connection between the upper part and the lower part of the cover to form an annular part of the radiation shield, and the first condensation plate is accommodated in the annular part of the radiation shield. Compared with the prior art, this structure effectively increases the upper space of the condensation plate, that is, increases the accommodation space of the condensation layer, and can improve the exhaust capacity limit of the cryogenic vacuum pump.

[0017] The present invention can maximize the exhaust capacity limit of the low-temperature vacuum pump by setting the reserved condensation layer thickness to be more than 85% of the height of the annular part of the radiation protection screen. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 It is a longitudinal cross-sectional view of an enlarged cryogenic vacuum pump disclosed in an embodiment of the present invention. DETAILED DESCRIPTION

[0019] The technical solution of the present invention is described in detail below in conjunction with specific implementation methods and the accompanying drawings.

[0020] First, the process of completing one embodiment of the present invention and its outline are described.

[0021] After the gas enters the radiation shield through the top opening, it contacts the condensation plate and is frozen. Since multiple condensation plates are arranged axially and the top condensation plate is located close to the opening of the radiation shield, most of the gas entering the radiation shield contacts the top condensation plate and is frozen, and only a small part of the gas is frozen by other condensation plates. Therefore, the volume of the gas condensation layer frozen on the top condensation plate determines the vacuum pump capacity limit of the cryogenic vacuum pump. If the area of ​​the top condensation plate can be increased, the volume of the gas condensation layer frozen on the top condensation plate can be increased, which can effectively improve the vacuum pump capacity limit of the cryogenic vacuum pump.

[0022] Factors that affect the volume of condensate on the condensation plate are as follows: The area of ​​the top condensation layer.

[0023] like Figure 1 As shown, the enlarged low-temperature vacuum pump of the present invention involves the following components: a refrigerator 11, a first cylinder 12, a primary cooling stage 13, a second cylinder 14, a secondary cooling stage 15, a cover body 20, a pump port mounting flange 21, a cover body upper part 22, 23-a cover body lower part, a cover body flange 24, a cover body flange upper part 241, a cover body flange lower part 242, a cover body annular part 25, a radiation shield 30, a radiation shield annular part 31, a baffle 32, a through hole 33, a first condensation plate 41, a second condensation plate 42, a third condensation plate 43, and a connecting plate 44.

[0024] like Figure 1 As shown, the enlarged cryogenic vacuum pump of the present invention comprises a housing 20, a radiation shield 30 is arranged inside the housing 20, and a refrigerator 11 is installed on the side of the housing 20. Figure 1In the figure, for the convenience of illustration, only a part of the refrigerator 11 is shown. The middle part of the radiation shield 30 extends outward to form a protruding radiation shield annular part 31. The refrigerator 11 extends into the radiation shield 30, and a plurality of condensation plates are horizontally arranged at the end of the refrigerator 11. A baffle 32 is arranged on the top of the radiation shield 30, and a plurality of through holes 33 are formed on the baffle 32, and gas enters the radiation shield 30 from the plurality of through holes 33. The baffle 32 is fixed to the mounting block of the radiation shield 30 in some way. For example Figure 1 As shown in FIG. 1 , threaded holes are formed on the mounting block and the baffle 32 , and the baffle 32 is fastened to the mounting block by bolts.

[0025] The refrigerator 11 is a two-stage refrigerator, including a first cylinder 12, a primary cooling stage 13 arranged at the output end of the first cylinder 12, a second cylinder 14 arranged at the end of the primary cooling stage 13, and a secondary cooling stage 15 arranged at the output end of the second cylinder 14. The primary cooling stage 13 is also connected to the radiation shield 30, and the secondary cooling stage 15 is also connected to a plurality of condensation plates. In this embodiment, the refrigerator 11 adopts an ultra-low temperature refrigerator such as a Gifford-McMahon refrigerator (i.e., the so-called GM refrigerator). The first cylinder 12 connects the room temperature part of the refrigerator 11 to the primary cooling stage 13, and the primary cooling stage 13 is cooled to a temperature within a range of, for example, 80K to 100K. The second cylinder 14 is a connecting part that connects the primary cooling stage 13 to the secondary cooling stage 15, and the secondary cooling stage 15 is cooled to a temperature within a range of, for example, 10K to 20K. Therefore, the radiation shield 30 can be cooled to a temperature within a range of 80 to 100K, and the plurality of condensation plates can be cooled to a temperature within a range of 10 to 20K.

[0026] The cover body 20 is a vacuum container that separates the interior of the cryogenic vacuum pump from the external environment. The cover body 20 contains a refrigerator 11 and a radiation shield 30. A pump port mounting flange 21 is installed on the outer side of the top of the cover body 20, and the pump port mounting flange 21 is used to connect the cryogenic vacuum pump and the chamber where a vacuum needs to be generated. The cover body 20 includes a cover body upper part 22 and a cover body lower part 23, and the cover body upper part 22 and the cover body lower part 23 are fixedly connected by a cover body flange 24. In this embodiment, the cover body flange 24 includes a cover body flange upper part 241 and a cover body flange lower part 242, and the cover body flange upper part 241 and the cover body flange lower part 242 both have screw holes (not shown in the figure), and the two are fastened together by bolts and nuts. The bottom of the cover upper part 22 extends outward to form the cover annular upper part, the top of the cover lower part 23 extends outward to form the cover annular lower part, and the cover annular upper part and the cover annular lower part are spliced ​​to form the cover annular part 25, so the cover annular part 25 is a part of the cover 20. The cover annular part 25 has a cover annular height.

[0027] The radiation shield 30 contains the second cylinder 14, the secondary cooling stage 15 and a plurality of condensing plates. The radiation shield 30 is thermally connected to the primary cooling stage 13, and is used to reduce the radiation heat received by the condensing plates from the cover body 20. The radiation shield 30 is located between the cover body 20 and the condensing plates. The circumference of the radiation shield 30 is cylindrical.

[0028] The radiation shield 30 has an annular portion 31 protruding around the central axis formed in the middle portion in the axial direction, and the annular portion 31 is included in the annular portion 25 of the housing. Figure 1 As shown, the radiation shield 30 has a radiation shield opening diameter 52, a radiation shield annular diameter 53 and a height 55 of the radiation shield annular portion 31. The radiation shield annular diameter 53 is significantly larger than the radiation shield opening diameter 52 and the cover opening diameter 57. The height 55 of the radiation shield annular portion 31 is more than 85% of the height 56 ​​of the cover annular portion 25.

[0029] A plurality of condensing panels are located inside the radiation shield 30 and are fixed to a connecting plate 44 , which is thermally connected to the secondary cooling stage 15 of the refrigerator 11 .

[0030] The plurality of condensation plates 40 are arranged in the radiation shield 30 in a manner that they are perpendicular to the axial direction and have their centers located at the same axis. The plurality of condensation plates 40 include a first condensation plate 41, a second condensation plate 42, and a third condensation plate 43. The first condensation plate 41 at the top is placed inside the radiation shield annular portion 31, and as shown in FIG. Figure 1 As shown, the space between the upper surface of the first condensation plate 41 and the annular portion 31 of the radiation shield is a reserved condensation layer, and the thickness of the reserved condensation layer is more than half of the height of the annular portion 31 of the radiation shield. The radius of the first condensation plate 41 is greater than the radius of the radiation shield 30, and less than the radius of the annular portion 31 of the radiation shield. In this embodiment, the thickness 51 of the reserved condensation layer is more than 85% of the height of the annular portion 31 of the radiation shield.

[0031] A second condensation plate 42 and a third condensation plate 43 are disposed in the radiation shield 30 below the first condensation plate 41 , and the second condensation plate 42 and the third condensation plate 43 are disposed horizontally and spaced apart.

[0032] The gas to be pumped enters the radiation shield 30 through the through hole 33, contacts the first condensation plate 41, and is condensed on the upper surface of the first condensation plate. The radius of the first condensation plate 41 is greater than the radius of the radiation shield 30, and smaller than the radius of the annular portion 31 of the radiation shield. In this embodiment, the radius of the first condensation plate 41 is more than 80% of the radius of the annular portion 31 of the radiation shield. In this way, the area of ​​the first condensation plate 41 is expanded, that is, the area of ​​the growth of the gas condensation layer is expanded. When the thickness of the gas condensation layer growth remains unchanged, the volume of the gas condensation layer becomes larger, that is, the pumping capacity limit of the low-temperature vacuum pump is increased.

[0033] The increase in the exhaust capacity limit of the cryogenic vacuum pump is associated with the radius of the first condensation plate 41 and the reserved condensation layer thickness 51. When the first condensation plate 41 does not contact the radiation shield 30, the larger the radius of the first condensation plate 41, the larger the reserved condensation layer thickness 51, the larger the volume of the gas condensation layer that can be accommodated on the upper surface of the first condensation plate 41, that is, the larger the exhaust capacity.

Claims

1. An enlarged cryogenic vacuum pump, characterized in that: It comprises a cover body (20), a radiation protection screen (30) arranged at intervals inside the cover body (20), a baffle (32) arranged on the top of the radiation protection screen (30), and a refrigerator (11) installed on the side of the cover body (20); The middle part of the radiation shield (30) extends outward to form a protruding radiation shield annular part (31); The baffle plate (32) is provided with a plurality of through holes (33), and the gas enters the interior of the radiation protection screen (30) through the plurality of through holes (33); The refrigerator (11) extends into the radiation shield (30), and a plurality of condensation plates are horizontally arranged at the end of the refrigerator (11), wherein the first condensation plate (41) at the top is placed inside the annular portion (31) of the radiation shield; The space between the upper surface of the first condensation plate (41) and the annular portion (31) of the radiation protection screen is a reserved condensation layer, and the thickness of the reserved condensation layer is more than half of the height of the annular portion (31) of the radiation protection screen.

2. The enlarged cryogenic vacuum pump according to claim 1, characterized in that: The cover body (20) comprises a cover body upper part (22) and a cover body lower part (23), and the cover body upper part (22) and the cover body lower part (23) are fixedly connected via a cover body flange (24).

3. The enlarged cryogenic vacuum pump according to claim 2, characterized in that: The cover flange (24) comprises a cover flange upper part (241) and a cover flange lower part (242), which are fastened together by bolts and nuts.

4. The enlarged cryogenic vacuum pump according to claim 2, characterized in that: The bottom of the upper part (22) of the cover body extends outward to form an annular upper part of the cover body, and the top of the lower part (23) of the cover body extends outward to form an annular lower part of the cover body. The annular upper part of the cover body and the annular lower part of the cover body are spliced ​​to form an annular part (25) of the cover body, which is used to accommodate the annular part (31) of the radiation protection screen; the height of the annular part (31) of the radiation protection screen is more than 85% of the height of the annular part (25) of the cover body.

5. The enlarged cryogenic vacuum pump according to claim 1, characterized in that: The reserved condensation layer has a thickness of more than 85% of the height of the annular portion (31) of the radiation shield.

6. The enlarged cryogenic vacuum pump according to claim 1, characterized in that: The radius of the first condensation plate (41) is greater than the radius of the radiation protection screen (30) and smaller than the radius of the annular portion (31) of the radiation protection screen.

7. The enlarged cryogenic vacuum pump according to claim 1, characterized in that: A second condensation plate (42) and a third condensation plate (43) are arranged in the radiation protection screen (30) below the first condensation plate (41), and the second condensation plate (42) and the third condensation plate (43) are arranged horizontally and spaced apart.

8. The enlarged cryogenic vacuum pump according to claim 1, characterized in that: The refrigerator (11) comprises a first cylinder (12), a primary cooling stage (13) arranged at the output end of the first cylinder (12), a second cylinder (14) arranged at the end of the primary cooling stage (13), and a secondary cooling stage (15) arranged at the output end of the second cylinder (14); wherein the primary cooling stage (13) is also connected to a radiation protection screen (30), and the secondary cooling stage (15) is also connected to a plurality of condensation plates.

9. The enlarged cryogenic vacuum pump according to claim 8, characterized in that: The radiation protection screen (30) is cooled to a temperature within the range of 80-100K, and the plurality of condensation plates are cooled to a temperature within the range of 10-20K.

10. The enlarged cryogenic vacuum pump according to claim 5, characterized in that: The plurality of condensation plates are fixedly mounted on a connecting plate (44), and the connecting plate (44) is thermally connected to the secondary cooling stage (15).

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