Vacuum pump

Abstract

The object of the present invention is to suppress the formation of reaction products on the base or the like. The vacuum pump of the present invention includes a rotor, a stator, a base, a heater, and a cover member. The rotor includes a multi-stage rotor blade and a rotor cylinder portion. The stator includes a multi-stage stator blade and a stator cylinder portion. The base houses the rotor and the stator. The heater heats the stator cylinder portion. The cover member covers the inner wall surface of the base on the exhaust downstream side of the ends of the rotor cylinder portion and the stator cylinder portion on the exhaust downstream side. One end of the cover member contacts the end of the stator cylinder portion on the exhaust downstream side in the third internal space. The other end of the cover member extends from the third internal space to a position overlapping the inner peripheral surface of the rotor cylinder portion.

Description

Technical Field

[0001] The present invention relates to a vacuum pump. Background Art

[0002] Some vacuum pumps include the following components: a turbo vane pump section including fixed vanes and rotating vanes; a traction pump section provided at a position more downstream of the exhaust than the turbo vane pump section. The vacuum pump can be used, for example, as a method for making a process chamber in which processes such as dry etching or chemical vapor deposition (CVD) are performed into a high vacuum.

[0003] The process is performed by supplying a gas into the process chamber. Therefore, when the vacuum pump discharges the gas, there is a possibility that reaction products are generated on the gas inlet surface of the vacuum pump and deposited on the gas inlet surface. It is necessary to remove the reaction products deposited on the gas inlet surface.

[0004] Therefore, in the vacuum pump of Patent Document 1, by providing a protective member on the gas inlet surface of the exhaust path of the vacuum pump, it is possible to prevent products from being deposited on the vacuum pump, so that component replacement of the vacuum pump is not required, and the maintenance cost of the vacuum pump is reduced.

[0005] [Prior Art Documents]

[0006] [Patent Documents]

[0007] [Patent Document 1] Japanese Patent Application Laid-Open No. 2017-2856 Summary of the Invention

[0008] [Problems to be Solved by the Invention]

[0009] In the vacuum pump, there is a gap between the end portion on the exhaust downstream side of the rotor cylinder portion constituting the traction pump section and the end portion of the protective member. Therefore, there is a case where the exhaust gas discharged from the traction pump section enters the space between the rotor cylinder portion and the base, and / or the space between the protective member and the base. As a result, when the temperature of the base decreases, reaction products are generated on the base. In addition, there is a case where the reaction products generated on the base are peeled off and discharged into the exhaust path. An object of the present invention is to suppress the inflow of exhaust gas into the space between the rotor cylinder portion and the base, and / or the space between the protective member and the base, and to suppress the generation of reaction products on components of the vacuum pump such as the base.

[0010] [Technical Means for Solving the Problems]

[0011] A vacuum pump according to an embodiment of the present invention includes a rotor, a stator, a base, a heater, and a cover member. The rotor includes a multi-stage rotor blade and a rotor cylinder portion. The stator includes a multi-stage stator blade and a stator cylinder portion. The base houses the rotor and the stator. The heater heats the stator cylinder portion. The cover member covers the inner wall surface of the base, and the inner wall surface of the base forms an internal space located on the exhaust downstream side of the end portions of the rotor cylinder portion and the stator cylinder portion on the exhaust downstream side. One end of the cover member contacts the end portion of the stator cylinder portion on the exhaust downstream side in the internal space. The other end of the cover member extends from the internal space to a position overlapping the inner peripheral surface of the rotor cylinder portion.

[0012] [Advantages of the Invention]

[0013] In the vacuum pump according to the above-described embodiment of the present invention, the other end of the cover member extends from the internal space to a position overlapping the inner peripheral surface of the rotor cylinder portion. Thus, it is possible to suppress the discharged gas from entering the space between the rotor cylinder portion and the base and / or the space between the cover member and the base by the rotor and the stator. In addition, the stator cylinder portion is heated by the heater, and in the internal space, one end of the cover member contacts the end portion of the stator cylinder portion on the exhaust downstream side. Thus, while heating the cover member, the vicinity of the cover member of the base is also heated. As a result, it is possible to suppress the generation of reaction products on the cover member and the base. [Description of the Drawings]

[0014] Figure 1 is a cross-sectional view of the vacuum pump according to the embodiment.

[0015] Figure 2A is a plan view of the cover member.

[0016] Figure 2B is a cross-sectional view taken along line A2 - A2 of the cover member.

[0017] Figure 3 is an enlarged view of the vicinity of the rotor cylinder portion and the stator cylinder portion.

[0018] Figure 4 is a view showing a modification of the installation position of the cover member.

[0019] Figure 5 is a view showing another modification of the installation position of the cover member.

[0020] [Description of Reference Numerals]

[0021] 1: Vacuum pump

[0022] 2: Housing

[0023] 11: First end portion

[0024] 12: Second end portion

[0025] 13: Air inlet

[0026] 3: Base

[0027] 14: Base end

[0028] 15: Inner wall surface

[0029] 15A: Bottom surface

[0030] 15B: Outer wall surface

[0031] 15C: Inner side wall surface

[0032] 16: Exhaust port

[0033] 4: Rotor

[0034] 21: Shaft

[0035] 22: Rotor blade

[0036] 23: Rotor cylindrical part

[0037] 5: Stator

[0038] 31: Stator blade

[0039] 32: Stator cylindrical part

[0040] 6, 6A, 6B: Cover member

[0041] 61: First part

[0042] 62: Second part

[0043] 62A: Notch part

[0044] 63: Third part

[0045] 7: Heater

[0046] 8: Flushing gas supply device

[0047] 81: Cleaning port

[0048] 82: Gas flow path

[0049] 9: Sealing member

[0050] 41A~41D: Bearing

[0051] 42: Motor

[0052] 42A: Motor rotor

[0053] 42B: Motor stator

[0054] A1: Axial direction

[0055] G1: First gap

[0056] G2: Second gap

[0057] G3: Third gap

[0058] S1: First internal space

[0059] S2: Second internal space

[0060] S3: Third internal space

[0061] S4: Fourth internal space Detailed implementation manner

[0062] Hereinafter, a vacuum pump according to an embodiment will be described with reference to the drawings. Figure 1 It is a cross-sectional view of the vacuum pump 1 of the embodiment. As Figure 1 shown, the vacuum pump 1 includes a housing 2, a base 3, a rotor 4, and a stator 5.

[0063] The housing 2 includes a first end portion 11, a second end portion 12, and a first internal space S1. An air inlet 13 is provided at the first end portion 11. The first end portion 11 is mounted on an object to be mounted (not shown). The object to be mounted is, for example, a process chamber of a semiconductor manufacturing apparatus. The first internal space S1 communicates with the air inlet 13. The second end portion 12 is located opposite to the first end portion 11 in the axial direction (hereinafter simply referred to as "axial direction A1") of the rotor 4. The second end portion 12 is connected to the base 3. The base 3 includes a base end portion 14. The base end portion 14 is connected to the second end portion 12 of the housing 2.

[0064] The rotor 4 includes a shaft 21. The shaft 21 extends along the axial direction A1. The shaft 21 is rotatably accommodated in the base 3. A first gap G1 is formed between the shaft 21 and the base 3. In addition, a second internal space S2 is formed between the inner wall surface of the rotor 4 and the base 3.

[0065] The rotor 4 includes multiple rotor blades 22 and a rotor cylinder portion 23. The multiple rotor blades 22 are respectively connected to the shaft 21. The plurality of rotor blades 22 are arranged at intervals along the axial direction A1. Although not shown, the multiple rotor blades 22 respectively extend radially with the shaft 21 as the center. In addition, only one of the multiple rotor blades 22 is labeled with a symbol in the drawing, and the symbols of the other rotor blades 22 are omitted. The rotor cylinder portion 23 is disposed below the multiple rotor blades 22. The rotor cylinder portion 23 extends along the axial direction A1.

[0066] The stator 5 includes multiple segments of stator vanes 31 and a stator cylinder portion 32. The multiple segments of stator vanes 31 are connected to the inner surface of the housing 2. The multiple segments of stator vanes 31 are arranged at intervals in the axial direction A1. The multiple segments of stator vanes 31 are respectively arranged between the multiple segments of rotor vanes 22. Although not shown in the figure, the multiple segments of stator vanes 31 respectively extend radially with the shaft 21 as the center. In addition, in the figure, only two of the multiple segments of stator vanes 31 are labeled, and the symbols of the other stator vanes 31 are omitted. The stator cylinder portion 32 is fixed in a state of being in thermal contact with the base 3. The stator cylinder portion 32 is arranged facing the rotor cylinder portion 23 with a slight gap in the radial direction of the rotor cylinder portion 23. A spiral groove is provided on the inner peripheral surface of the stator cylinder portion 32.

[0067] As Figure 1 shown, on the more downstream side of the end of the exhaust downstream side of the rotor cylinder portion 23 and the stator cylinder portion 32, the inner wall surface 15 of the base 3 forms a third internal space S3. The gas discharged from the object to be installed and the purge gas described below are discharged into the third internal space S3. The third internal space S3 communicates with the exhaust port 16. The exhaust port 16 is provided on the base 3. Another vacuum pump (not shown) is connected to the exhaust port 16. In addition, the exhaust downstream side means the side closer to the third internal space S3 in the axial direction A1. In addition, the exhaust downstream direction means the direction toward the third internal space S3.

[0068] The vacuum pump 1 includes multiple bearings 41A to 41D and a motor 42. The multiple bearings 41A to 41D are installed at the position of the housing shaft 21 of the base 3. The multiple bearings 41A to 41D rotatably support the rotor 4. The bearing 41A is a ball bearing, for example. On the other hand, the other bearings 41B to 41D are magnetic bearings, for example. However, the multiple bearings 41B to 41D can also be other types of bearings such as ball bearings.

[0069] The motor 42 rotationally drives the rotor 4. The motor 42 includes a motor rotor 42A and a motor stator 42B. The motor rotor 42A is installed on the shaft 21. The motor stator 42B is installed on the base 3. The motor stator 42B is arranged facing the motor rotor 42A.

[0070] In the vacuum pump 1, the multiple segments of rotor vanes 22 and the multiple segments of stator vanes 31 constitute a turbomolecular pump section. In addition, the rotor cylinder portion 23 and the stator cylinder portion 32 constitute a thread groove pump section. In the vacuum pump 1, the motor 42 rotates the rotor 4, whereby gas flows into the first internal space S1 from the suction port 13. The gas in the first internal space S1 is discharged to the third internal space S3 through the turbomolecular pump section and the thread groove pump section. The gas in the third internal space S3 is discharged from the exhaust port 16. As a result, the inside of the object to be installed connected to the suction port 13 becomes a high vacuum state.

[0071] When performing a process such as dry etching or CVD inside an object to be installed at the suction port 13, the vacuum pump 1 discharges the gas (referred to as "process gas") used in these processes. As a result, there is a case where reaction products are generated from the process gas in the exhaust path of the vacuum pump 1. Therefore, in the present embodiment, a cover member 6 is provided in the third internal space S3 that forms the exhaust path of the vacuum pump 1 to suppress the generation of reaction products on the base 3 constituting the vacuum pump 1. Hereinafter, the structure of the cover member 6 will be specifically described.

[0072] Figure 2A is a plan view of the cover member 6. Figure 2B is a sectional view taken along line A2 - A2 of the cover member 6. Figure 3 is an enlarged view near the rotor cylinder portion 23 and the stator cylinder portion 32. The cover member 6 includes a first portion 61, a second portion 62, and a third portion 63. The first portion 61 is an annular planar member. When the cover member 6 is disposed in the third internal space S3, the first portion 61 covers the bottom surface 15A of the inner wall surface 15 of the base 3. In addition, the cover member 6 is fixed to the base 3 by bolting the first portion 61 to the bottom surface 15A of the base 3. Thus, the cover member 6 can be easily detached from the base 3.

[0073] The second portion 62 is an annular wall portion that is connected to the outer peripheral side of the first portion 61. When the cover member 6 is disposed in the third internal space S3, the second portion 62 covers the outer wall surface 15B of the inner wall surface 15 of the base 3. The third portion 63 is an annular wall portion that is connected to the inner peripheral side of the first portion 61. When the cover member 6 is disposed in the third internal space S3, the third portion 63 covers the inner wall surface 15C of the inner wall surface 15 of the base 3.

[0074] The gaps between the first portion 61, the second portion 62, and the third portion 63 and the inner wall surface 15 of the base 3 covered by these portions are set as small as possible. Thereby, it is possible to suppress as much as possible the deposition of reaction products on the inner wall surface 15 of the base 3 covered by the first portion 61, the second portion 62, and the third portion 63.

[0075] As Figure 2A and Figure 2B shown, a cutout portion 62A is formed in a part of the second portion 62. When the cover member 6 is disposed in the third internal space S3, the cutout portion 62A faces the exhaust port 16 ( Figure 1 ). The gas discharged to the exhaust side of the screw groove pump portion including the rotor cylinder portion 23 and the stator cylinder portion 32 flows into the third internal space S3 and then is discharged from the exhaust port 16 through the cutout portion 62A.

[0076] The lid member 6 is formed, for example, by bending a plate material such as aluminum alloy or stainless steel. In addition, the first part 61, the second part 62, and the third part 63 can be formed from plate materials respectively, and these parts can be welded to form the lid member 6. In order to improve the corrosion resistance, the surface of the lid member 6 can be subjected to a surface treatment using nickel plating (such as electroless nickel plating). In addition, in order to easily absorb the radiation from the rotor 4, a black coating such as black nickel plating with a high emissivity can also be formed. Furthermore, a surface treatment using nickel plating or black nickel plating containing fluororesin can be implemented instead of nickel plating and black nickel plating.

[0077] As Figure 3 shown, one end on the outer peripheral side of the lid member 6 contacts the end on the exhaust downstream side of the stator cylinder part 32. Specifically, one end of the second part 62 contacts the end on the exhaust downstream side of the stator cylinder part 32. On the other hand, the other end on the inner peripheral side of the lid member 6 extends from the third internal space S3 to a position overlapping with the inner peripheral surface of the rotor cylinder part 23. Specifically, one end of the third part 63 extends from the third internal space S3 to a position overlapping with the inner peripheral surface of the rotor cylinder part 23.

[0078] As described above, in the vacuum pump 1, one end on the outer peripheral side of the lid member 6, that is, one end of the second part 62, contacts the end on the exhaust downstream side of the stator cylinder part 32. Thus, the lid member 6 becomes approximately the same temperature as the stator cylinder part 32. In order to heat the stator cylinder part 32, the vacuum pump 1 includes a heater 7. The heater 7 is provided on the base 3. The heater 7 heats the stator cylinder part 32 that is in thermal contact with the base 3 by heating the base 3. As Figure 3 shown, the heater 7 can be fixed to the outer periphery of the base 3 or can be embedded in the base 3. The stator cylinder part 32 is heated to a temperature at which reaction products will not be generated. The heating temperature of the stator cylinder part 32 can be arbitrarily set according to the gas used inside the installation object, the type of reaction products, etc. The heating temperature is, for example, 150 °C.

[0079] By heating the stator cylinder part 32 to the above temperature, the lid member 6 is also heated to a temperature at which reaction products will not be generated, thereby suppressing the generation of reaction products on the lid member 6. In addition, the inner side wall surface 15C of the base 3 is heated by the radiation from the other end on the outer peripheral side of the lid member 6. Thus, the generation of reaction products on the base 3 is also suppressed.

[0080] In addition, in the vacuum pump, the other end of the inner peripheral side of the lid member 6, i.e., one end of the third portion 63, extends from the third internal space S3 to a position overlapping the inner peripheral surface of the rotor cylinder portion 23. Thereby, it is possible to suppress the gas discharged into the third internal space S3 from entering the space between the rotor cylinder portion 23 and the base 3 and / or the space between the third portion 63 of the lid member 6 and the base 3. As a result, it is possible to suppress the formation of reaction products on the base 3, the rotor cylinder portion 23, and the lid member 6 (third portion 63).

[0081] The overlapping length of the third portion 63 and the side surface on the exhaust downstream side of the rotor cylinder portion 23 is set to a length such that the rotor 4 will not be overheated by the lid member 6. For example, the overlapping length is 50% or less of the length of the rotor cylinder portion 23, preferably about 10% of the length of the rotor cylinder portion 23. Thereby, it is possible to prevent the rotor 4 from expanding and contacting other components of the vacuum pump 1.

[0082] The vacuum pump 1 includes a purge gas supply device 8. The purge gas supply device 8 includes a cleaning port 81 and a gas flow path 82. The cleaning port 81 is connected to a supply source (not shown) of the purge gas. The cleaning port 81 is connected to the gas flow path 82. The gas flow path 82 communicates with the first gap G1 between the base 3 and the shaft 21. The first gap G1 communicates with the second internal space S2. The purge gas introduced into the cleaning port 81 from the supply source of the purge gas is introduced into the second internal space S2 through the gas flow path 82 and the first gap G1. The purge gas introduced into the second internal space S2 is discharged in the exhaust downstream direction from the second gap G2 formed between the other end (third portion 63) on the inner peripheral side of the lid member 6 and the side surface on the inner peripheral side of the rotor cylinder portion 23. Thereby, the purge gas discharged from the second gap G2 is discharged into the third internal space S3 and then discharged from the exhaust port 16. The purge gas is, for example, an inert gas such as nitrogen.

[0083] By discharging the purge gas from the second gap G2 into the third internal space S3, it is possible to suppress the gas discharged from the screw groove pump into the third internal space S3 from invading the second internal space S2 through the second gap G2. As a result, it is possible to suppress the formation of reaction products on the base 3 and the side wall of the rotor 4 constituting the second internal space S2.

[0084] The vacuum pump 1 includes a sealing member 9. The sealing member 9 has an annular shape when viewed from above. The cross-section of the sealing member 9 is L-shaped. The sealing member 9 is disposed between the base 3 and the rotor cylinder portion 23. Specifically, the short side of the L-shape of the sealing member 9 is fixed to the convex portion provided on the base 3. On the other hand, the long side of the L-shape of the sealing member 9 faces the inner peripheral side surface of the rotor cylinder portion 23 at the upper part of the other end on the inner peripheral side of the cover member 6. A threaded groove is formed along the axial direction A1 on the surface of the long side of the L-shape of the sealing member 9 on the side facing the rotor cylinder portion 23. A third gap G3 is provided between the long side of the L-shape of the sealing member 9 and the inner peripheral side surface of the rotor cylinder portion 23. The third gap G3 is sufficiently narrow.

[0085] By forming a threaded groove on the surface of the long side of the L-shape of the sealing member 9 on the side facing the rotor cylinder portion 23 and making the third gap G3 between the sealing member 9 and the rotor cylinder portion 23 narrow, when the rotor 4 rotates at a high speed, a gas flow in the direction of the exhaust downstream, that is, in the direction of the third internal space S3, is generated in the third gap G3. As a result, it is possible to prevent the gas discharged from the threaded groove pump including the rotor cylinder portion 23 and the stator cylinder portion 32 into the third internal space S3 from invading the second internal space S2 through the second gap G2 and the third gap G3. In addition, when the rotor 4 rotates at a high speed, as long as a gas flow in the exhaust downstream direction can be generated in the third gap G3, a threaded groove may not be formed on the long side of the L-shape of the sealing member 9.

[0086] When assembling the vacuum pump 1, the cover member 6 is inserted from the upper part of the base 3 and installed on the inner wall surface 15, and then the rotor 4 is assembled to the base 3. In this case, in order to overlap one end of the third portion 63 of the cover member 6 with the inner peripheral surface of the rotor cylinder portion 23, it is necessary to previously form the base 3 such that the gap between the base 3 and the rotor cylinder portion 23 is equal to or greater than the thickness of the third portion 63. In the completed vacuum pump 1, if the gap between the base 3 and the rotor cylinder portion 23 is equal to or greater than the thickness of the third portion 63, then even if the rotor 4 rotates at a high speed, it is difficult for the gap to generate a gas flow in the exhaust downstream direction. As a result, the gas discharged into the third internal space S3 easily invades the second internal space S2 through the gap.

[0087] Therefore, by forming the sealing member 9 as a separate member, inserting the cover member 6 from the upper part of the base 3 and installing it on the inner wall surface 15, and then making the sealing member 9 face the rotor cylinder portion 23, it is possible to form a narrow third gap G3 between the base 3 (sealing member 9) and the rotor cylinder portion 23. As a result, when the rotor 4 rotates at a high speed, a gas flow in the exhaust downstream direction easily occurs in the third gap G3 between the sealing member 9 and the rotor cylinder portion 23.

[0088] In the vacuum pump 1 of the present embodiment described above, the other end of the cover member 6, that is, one end of the third portion 63, extends from the third internal space S3 to a position overlapping with the inner peripheral surface of the rotor cylinder portion 23. Thereby, it is possible to suppress the discharged gas from entering the space between the rotor cylinder portion 23 and the base 3 and / or the space between the cover member 6 and the base 3 by the rotor 4 and the stator 5.

[0089] In addition, in the vacuum pump 1 of the present embodiment, the stator cylinder portion 32 is heated by the heater 7, and one end (the second portion 62) of the cover member 6 contacts the end portion on the exhaust downstream side of the stator cylinder portion 32 in the third internal space S3. Thereby, while heating the cover member 6, the vicinity of the cover member 6 of the base 3 is also heated. As a result, it is possible to suppress the generation of reaction products on the cover member 6 and the base 3.

[0090] One embodiment of the present invention has been described above, but the present invention is not limited to the above-described embodiment, and various modifications can be made without departing from the gist of the invention.

[0091] The vacuum pump 1 of the above-described embodiment is a pump in which a turbomolecular pump and a screw groove pump are integrated. The turbomolecular pump includes multiple stages of rotor blades 22 and multiple stages of stator blades 31, and the screw groove pump includes a rotor cylinder portion 23 and a stator cylinder portion 32. However, the screw groove pump can also be omitted. That is, the vacuum pump 1 can also be a turbomolecular pump. Or the turbomolecular pump can also be omitted. That is, the vacuum pump 1 can also be a screw groove pump.

[0092] A member similar to the cover member 6 can be provided in the exhaust path other than the inner wall surface 15 of the base 3 that forms the third internal space S3. For example, as Figure 4 shown, a cover member 6A can be provided in the fourth internal space S4 formed between the turbomolecular pump and the screw groove pump. In addition, as Figure 5 shown, a cover member 6B can also be provided on the inner wall surface of the exhaust port 16. Figure 4 and Figure 5 are diagrams showing a modified example of the installation position of the cover member 6A.

[0093] Those skilled in the art understand that the above-described multiple exemplary embodiments are specific examples of the following embodiments.

[0094] (First Embodiment) The vacuum pump includes a rotor, a stator, a base, a heater, and a cover member. The rotor includes multiple stages of rotor blades and a rotor cylindrical portion. The stator includes multiple stages of stator blades and a stator cylindrical portion. The base houses the rotor and the stator. The heater heats the stator cylindrical portion. The cover member covers the inner wall surface of the base, and the inner wall surface of the base forms an internal space located on the exhaust downstream side of the end portions of the rotor cylindrical portion and the stator cylindrical portion. One end of the cover member contacts the end portion on the exhaust downstream side of the stator cylindrical portion in the internal space. The other end of the cover member extends from the internal space to a position overlapping the inner peripheral surface of the rotor cylindrical portion.

[0095] In the vacuum pump of the first embodiment, the other end of the cover member extends from the internal space to a position overlapping the inner peripheral surface of the rotor cylindrical portion. Thereby, it is possible to suppress the discharged gas from entering the space between the rotor cylindrical portion and the base and / or the space between the cover member and the base by the rotor and the stator. In addition, the stator cylindrical portion is heated by the heater, and one end of the cover member contacts the end portion on the exhaust downstream side of the stator cylindrical portion in the internal space. Thereby, while heating the cover member, the vicinity of the cover member of the base is also heated. As a result, reaction products can be suppressed from being generated on the cover member and the base.

[0096] (Second Embodiment) In the vacuum pump of the first embodiment, the cover member can be formed in a ring shape. In the vacuum pump of the second embodiment, it is easy to install the cover member on the vacuum pump.

[0097] (Third Embodiment) In the vacuum pump of the first or second embodiment, the cover member can include: a first portion covering the bottom surface of the inner wall surface of the base; a second portion covering the outer side wall surface of the inner wall surface of the base and connected to the first portion; and a third portion covering the inner side wall surface of the inner wall surface of the base and connected to the first portion. In addition, the second portion can contact the end portion on the exhaust downstream side of the stator cylindrical portion in the internal space, and the third portion can extend from the internal space to a position overlapping the inner peripheral surface of the rotor cylindrical portion.

[0098] In the vacuum pump of the third embodiment, the third portion of the cover member extends from the internal space to a position overlapping the inner peripheral surface of the rotor cylindrical portion. Thereby, it is possible to suppress the discharged gas from entering the space between the rotor cylindrical portion and the base and / or the space between the cover member and the base by the rotor and the stator. In addition, the stator cylindrical portion is heated by the heater, and the second portion of the cover member contacts the end portion on the exhaust downstream side of the stator cylindrical portion in the internal space. Thereby, while heating the cover member, the vicinity of the cover member of the base is also heated. As a result, reaction products can be suppressed from being generated on the cover member and the base.

[0099] (Fourth Embodiment) The vacuum pump according to any one of the first to third embodiments may further include a sealing member. The sealing member may be disposed on the upper portion of the other end of the cover member so as to face the side surface on the inner peripheral side of the rotor cylinder portion. In the vacuum pump of the fourth embodiment, a narrow gap is formed between the sealing member and the rotor cylinder portion, and a gas flow in the exhaust downstream direction can be generated. As a result, the intrusion of the exhausted gas from the gap can be suppressed.

[0100] (Fifth Embodiment) The vacuum pump according to any one of the first to fourth embodiments may further include a purge gas supply device. The purge gas supply device supplies purge gas to the gap formed between the other end of the cover member and the side surface on the inner peripheral side of the rotor cylinder portion along the exhaust downstream direction. Thereby, the intrusion of the exhausted gas from the gap formed between the other end of the cover member and the side surface on the inner peripheral side of the rotor cylinder portion can be suppressed.

[0101] (Sixth Embodiment) In the vacuum pump of the fourth embodiment, the sealing member may be formed as a member different from the base and connected to the base. By forming the sealing member as a different member, inserting the cover member from the upper portion of the base and installing it on the inner wall surface, and then making the sealing member face the rotor cylinder portion, a narrow gap can be formed between the sealing member and the rotor cylinder portion. As a result, a gas flow in the exhaust downstream direction is likely to be generated.

[0102] (Seventh Embodiment) In the vacuum pump according to any one of the first to sixth embodiments, the length of the overlap between the other end of the cover member and the inner peripheral surface of the rotor cylinder portion may be 50% or less of the length of the rotor cylinder portion in the axial direction. It is possible to prevent the rotor 4 from expanding and contacting other components of the vacuum pump 1.

Claims

1. A vacuum pump, wherein, Comprising: A rotor, including multiple segments of rotor blades and a rotor cylindrical portion; A stator, including multiple segments of stator blades and a stator cylindrical portion; A base for housing the rotor and the stator; And A cover member covering the inner wall surface of the base, the inner wall surface of the base forming an internal space located on the exhaust downstream side of the end portions of the rotor cylindrical portion and the stator cylindrical portion on the exhaust downstream side; The cover member includes: A first portion covering and fixed to the bottom surface of the inner wall surface of the base; A second portion covering the outer side wall surface of the inner wall surface of the base and continuously connected to the first portion; and A third portion covering the inner side wall surface of the inner wall surface of the base and continuously connected to the first portion, The third portion extends from the internal space to a position overlapping the inner circumferential surface of the rotor cylindrical portion, The first portion is disposed between the second portion and the third portion, and the first portion is in continuous contact with the bottom surface of the inner wall surface of the base.

2. The vacuum pump according to claim 1, wherein The cover member is formed in a ring shape.

3. The vacuum pump according to claim 1 or 2, further comprising: A sealing member disposed in a manner facing the side surface of the inner circumferential side of the rotor cylindrical portion at the upper part of one end on the inner circumferential side of the cover member.

4. The vacuum pump according to claim 1 or 2, further comprising: A purge gas supply device for supplying purge gas along the exhaust downstream direction to the gap formed between one end on the inner circumferential side of the cover member and the side surface of the inner circumferential side of the rotor cylindrical portion.

5. The vacuum pump according to claim 3, wherein The sealing member is formed as a member different from the base and is connected to the base.

6. The vacuum pump according to claim 1 or 2, wherein The length of the overlap between one end on the inner circumferential side of the cover member and the inner circumferential surface of the rotor cylindrical portion is 50% or less of the axial length of the rotor cylindrical portion.

7. The vacuum pump according to claim 1 or 2, further comprising: A heater for heating the stator cylindrical portion, Using the heater to heat one end on the outer circumferential side of the cover member.

8. The vacuum pump according to claim 1 or 2, wherein A heater for heating the stator cylindrical portion, One end on the outer circumferential side of the cover member contacts the exhaust downstream side end portion of the stator cylindrical portion in the internal space.

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