Vacuum pump and leak detector

Abstract

The present invention is to prevent slow gas leakage caused by gas accumulation between a housing and a component fixed to the housing in a vacuum pump. The vacuum pump (100, 100a) of the present invention includes: a rotor (20) that can rotate along a specific rotation direction; a housing (11) that accommodates the rotor (20); and a fixing component (30, 40) that is arranged in a manner facing the inner wall of the housing (11), a gap (S1, S1a) is formed between the inner wall of the housing (11) and the fixing component (30, 40), and a groove (111a, 111b, 311, 411) that connects the gap (S1, S1a) with the exhaust path inside the housing (11) is formed on the inner wall of the housing (11) and any one of the fixing components (30, 40). The leak detector including the vacuum pump suppresses the slow gas leakage of the vacuum pump, thereby shortening the time for the leakage rate to drop to close to the background in a test, thereby performing a rapid leak inspection.

Description

Technical Field

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

[0002] Turbomolecular pumps are used as vacuum pumps for ultra-high vacuum and leak detectors. Turbomolecular pumps house a rotor inside a housing and perform vacuum exhaust by rotating the rotor tens of thousands of times.

[0003] In a rotor rotating at high speed, if a closed space is formed in the combined part of the components, there is a problem of slow gas leakage in which the gas sealed in the closed space gradually leaks out. Patent document 1 discloses a method of eliminating slow gas leakage by eliminating the closed space in part of the rotor.

[0004] [Prior art literature]

[0005] [Patent Document]

[0006] [Patent Document 1] Japanese Patent Application Publication No. 2020-197127 Summary of the invention

[0007] [Problems to be solved by the invention]

[0008] In a vacuum pump, there is also the possibility of gas accumulation in the housing and components fixed to the housing, resulting in a possibility of slow gas leakage. The purpose of the present disclosure is to provide a method for eliminating such gas accumulation and eliminating slow gas leakage.

[0009] [Technical means to solve the problem]

[0010] The vacuum pump of the present disclosure comprises:

[0011] A rotor, capable of rotating in a specific direction of rotation;

[0012] a housing for accommodating the rotor; and

[0013] The fixing assembly is arranged to face the inner wall of the housing.

[0014] A gap is formed between the inner wall of the housing and the fixing assembly,

[0015] A groove is formed in one of an inner wall of the housing and the fixing member, and the groove allows the gap to communicate with an exhaust path inside the housing.

[0016] The leak detector disclosed herein comprises:

[0017] A vacuum pump is the vacuum pump of the present disclosure, comprising a first air intake port, an air exhaust port, and a second air intake port connected to an exhaust path between the first air intake port and the air exhaust port; and

[0018] Analytical tube, leak detection gas,

[0019] The analysis tube is connected to the first air inlet of the vacuum pump.

[0020] The object under test is connected to the second air suction port of the vacuum pump.

[0021] [Effects of the Invention]

[0022] The vacuum pump disclosed herein has a gap formed between a housing and a fixing assembly fitted on the inner wall of the housing, and a groove for exhausting the gap is provided on the housing or the fixing assembly, thereby being able to suppress slow gas leakage.

[0023] In addition, the leak detector of the present disclosure suppresses the slow leakage of the vacuum pump, so that the time for the leakage rate to decrease to a level close to the background in one test can be shortened, thereby performing a rapid leak inspection. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 It is a cross-sectional view of the vacuum pump 100 according to the first embodiment.

[0025] Figure 2 It is an enlarged view of the fitting portion between the step of the inner wall of the housing 11 and the magnetic retainer 30 according to the first embodiment.

[0026] Figure 3 It is a perspective view of the magnetic retainer 30 according to the first embodiment.

[0027] Figure 4 This is a diagram showing a portion of the magnetic retainer 30 according to the first embodiment as viewed from the upper surface.

[0028] Figure 5 It is an enlarged view of the fitting portion between the step of the inner wall of the housing 11 and the magnetic retainer 30 according to the modification 1A.

[0029] Figure 6 It is an enlarged view of the fitting portion between the step of the inner wall of the housing 11 and the magnetic retainer 30 according to the modification 1B.

[0030] Figure 7 It is a cross-sectional view of a vacuum pump 100 a according to the second embodiment.

[0031] Figure 8 It is an enlarged view of a fitting portion between a step of the inner wall of the housing 11 and the spacer 40 according to the second embodiment.

[0032] Fig. 9 It is a diagram showing the structure of a leak detector 500 according to the third embodiment.

[0033] [Explanation of Symbols]

[0034] 10: Shell

[0035] 11: Shell

[0036] 12: Base

[0037] 20: Rotor

[0038] 21: Rotor blade unit

[0039] 22: Rotor blades

[0040] 23: Stator blade unit

[0041] 24: Stator blades

[0042] 25: Rotor cylinder

[0043] 26: Stator cylinder

[0044] 27: Axis

[0045] 28: Motor

[0046] 30: Magnetic retainer

[0047] 31: Outer ring of magnetic retainer

[0048] 32: Beam of magnetic retainer

[0049] 40: Spacer

[0050] 100: Vacuum pump

[0051] 200: Analysis tube

[0052] 300: Roughing pump

[0053] 400: Sample

[0054] 111a, 111b, 311, 411: slot

[0055] P11: First air intake

[0056] P12, P13: Second air intake

[0057] P21: Exhaust port

[0058] R1, R2: Arc part

[0059] R11, R22: Radius

[0060] S1, S1a: gap DETAILED DESCRIPTION

[0061] <First Embodiment>

[0062] like Figure 1As shown, the vacuum pump 100 of the first embodiment includes a housing 10, a rotor 20, a motor 28, a magnetic retainer 30, a multi-stage stator blade unit 23, a stator cylindrical portion 26, a bearing 51, a bearing 52, and a bearing 55. The housing 10 includes a shell 11 and a base 12. The housing 10 accommodates the rotor 20, the motor 28, the magnetic retainer 30, the multi-stage stator blade unit 23, the stator cylindrical portion 26, the bearing 51, the bearing 52, and the bearing 55.

[0063] like Figure 1 As shown, the housing 10 includes a first air intake port P11, a second air intake port P12, a second air intake port P13, and an exhaust port P21. An exhaust target device including an exhaust target space is connected to the air intake port P11. An auxiliary pump is connected to the exhaust port. An exhaust path from the first air intake port P11 to the exhaust port P21 is formed in the internal space of the housing 10. A plurality of second air intake ports P12 and second air intake ports P13 are connected to the exhaust path. When the vacuum pump 100 is used as a leak detector, pipes from the sample are respectively connected to the plurality of second air intake ports P12 and second air intake ports P13.

[0064] The rotor 20 includes a shaft 27 , a plurality of stages of rotor blade units 21 , and a rotor cylindrical portion 25 .

[0065] The shaft 27 extends along the axial direction A1 of the rotor 20. In the following description, in the axial direction A1, the direction from the housing 11 toward the base 12 is defined as a downward direction, and the opposite direction is defined as an upward direction.

[0066] The shaft 27 is rotatably fixed to the housing 10 via the bearing 51, the bearing 52, and the magnetic bearing 55. More specifically, the upper portion of the shaft 27 is fixed to the magnetic retainer 30 via the bearing 51 and the magnetic bearing 55, and the magnetic retainer 30 is fixed to the housing 11. The lower portion of the shaft 27 is fixed to the base 12 via the bearing 52.

[0067] The motor 28 drives the rotor 20 to rotate. The motor 28 includes a motor rotor 28a and a motor stator 28b. The motor rotor 28a is mounted on the shaft 27. The motor stator 28b is mounted on the base 12. The motor stator 28b and the motor rotor 28a are arranged to face each other.

[0068] The plurality of rotor blade units 21 are connected to the shaft 27, respectively. The plurality of rotor blade units 21 are arranged at intervals along the axial direction A1. Each rotor blade unit 21 includes a plurality of rotor blades 22. Although not shown in the figure, the plurality of rotor blades 22 extend radially with the shaft 27 as the center. In addition, in the figure, only one of the plurality of rotor blade units 21 and one of the plurality of rotor blades 22 are marked with a symbol, and the symbols of the other rotor blade units 21 and the other rotor blades 22 are omitted.

[0069] The multiple-stage stator blade units 23 are sandwiched between two spacers 45 arranged up and down and are stacked on the inner surface of the housing 11. The multiple-stage stator blade units 23 are arranged at intervals from each other in the axial direction A1. The multiple-stage stator blade units 23 are respectively arranged between the multiple-stage rotor blade units 21. Each stator blade unit 23 includes a plurality of stator blades 24. Although not shown in the figure, the multiple-stage stator blades 24 extend radially with the shaft 27 as the center.

[0070] The multiple stages of rotor blade units 21 and stator blade units 23 constitute a turbomolecular pump. In the drawings, only one of the multiple stator blade units 23 and one of the multiple stator blades 24 are denoted by reference numerals, and reference numerals of the other stator blade units 23 and other stator blades 24 are omitted.

[0071] The rotor cylindrical portion 25 is disposed below the rotor blade unit 21. The rotor cylindrical portion 25 extends along the axial direction A1.

[0072] The stator cylindrical portion 26 is arranged radially outside the rotor cylindrical portion 25. The stator cylindrical portion 26 is fixed to the housing 10. The stator cylindrical portion 26 is arranged facing the rotor cylindrical portion 25 in the radial direction of the rotor cylindrical portion 25. A spiral groove is provided on the inner circumferential surface of the stator cylindrical portion 26. The rotor cylindrical portion 25 and the stator cylindrical portion 26 constitute a thread groove pump.

[0073] The magnetic retainer 30 retains the permanent magnets on the inner circumference of the magnetic bearing 55 and positions the permanent magnets on the inner circumference in the radial and axial directions. The magnetic retainer 30 is fitted into the inner wall of the housing 11 and is disposed above the shaft 27 of the rotor 20. Figure 3 As shown, the magnetic retainer 30 includes a central portion 33, an outer ring portion 31, and a beam 32 connecting the central portion 33 and the outer ring portion 31. The outer ring portion 31 is fitted into the inner wall of the housing 11. The permanent magnet on the inner circumference side of the magnetic bearing 55 is fixed to the central portion 33. On the other hand, the permanent magnet on the outer circumference side of the magnetic bearing 55 is fixed to the rotor 20. The repulsive force generated by the magnetic force of the permanent magnet on the inner circumference side of the magnetic bearing 55 and the permanent magnet on the outer circumference side causes the rotor 20 to float to a specific position toward the upper side of the axial direction A1.

[0074] like Figure 3 As shown, the outer ring portion 31 of the magnetic retainer 30 has a step difference. The step difference includes the outer peripheral surface 31a and the radial surface 31b. In addition, the inner wall of the housing 11 also has a step difference. Figure 2As shown, the step difference includes a surface 11a extending in the up-down direction and a surface 11b extending in the radial direction. The outer peripheral surface 31a of the magnetic retainer 30 is fitted in a manner connected to the inner wall surface 11a of the shell 11. In addition, the surface 31b of the magnetic retainer 30 is connected to the surface 11b constituting the step difference of the shell 11. This structure forms a gap S1 between the shell 11 and the magnetic retainer 30 at the step difference of the inner wall of the shell 11. If the gap S1 is a closed space, it becomes a gas accumulation, resulting in slow leakage.

[0075] In this embodiment, a groove 311 is formed on the outer peripheral surface 31a of the outer ring portion 31 of the magnetic retainer 30. The groove 311 connects the gap S1 with other spaces inside the housing 11. The other spaces become exhaust paths. Therefore, it is easy to exhaust the gap S1 and suppress slow leakage. In detail, the groove 311 and the small gap between the spacer 45 and the housing 11 (see Figure 1 ). The gap between the spacer 45 and the housing 11 is connected to the air inlet P12 at the bottom, and is therefore connected to the exhaust path between the turbomolecular pump and the thread groove pump. Therefore, the gas in the gap S1 is discharged to the exhaust path between the turbomolecular pump and the thread groove pump via the groove 311 and the gap between the spacer 45 and the housing 11.

[0076] like Figure 4 As shown, the groove 311 is preferably formed in the portion of the outer ring portion 31 connected to the beam 32. When the groove 311 is processed, the portion has high rigidity due to the beam 32 and is not easily deformed. If the magnetic retainer 30 is deformed, the rotation axis of the rotor 20 deviates from the center, etc., which is not good. The groove 311 is preferably arranged between the radius R11 and the radius R22 of the end of the outer side of the arc R1 passing through the connection between the beam 32 and the outer ring portion 31 and the arc R2 (the radius refers to the straight line connecting the end and the center of the outer ring portion 31).

[0077] <Variation 1A of the First Embodiment>

[0078] In the first embodiment, if Figure 2 As shown in FIG. 1 , a groove 311 is formed in the magnetic retainer 30 so that the gap S1 between the housing 11 and the magnetic retainer 30 communicates with the exhaust path inside the housing 11. Figure 5 As shown, the groove 111a is formed on the surface 11a extending in the vertical direction of the housing 11. The structure of the other modification 1A is the same as that of the first embodiment. In the case of modification 1A, the gas accumulated in the gap S1 between the housing 11 and the magnetic retainer 30 is also easily discharged to the exhaust path through the groove 111a, thereby suppressing the occurrence of slow leakage.

[0079] <Variation 1B of the First Embodiment>

[0080] In the modification 1A, the groove 111a is formed on the surface 11a extending in the vertical direction of the housing 11. In contrast, in the modification 1B, as shown in FIG. Figure 6 As shown, the groove 111b is formed on the surface 11b of the housing 11 extending radially along the step difference. The structure of other variants 1B is the same as that of the first embodiment. In the case of variant 1B, the gas accumulated in the gap S1 between the housing 11 and the magnetic retainer 30 is also easily discharged to the exhaust path via the groove 111b, thereby suppressing the occurrence of slow leakage. In detail, the groove 111 is connected to the gap between the magnetic retainer 30 and the housing 11 at the upper part of the axial direction. The gap between the magnetic retainer 30 and the housing 11 at the upper part of the axial direction is connected to the space above the magnetic retainer 30. Therefore, the gas in the gap S1 is discharged to the exhaust path upstream of the turbomolecular pump via the groove 311 and the gap between the magnetic retainer 30 and the housing 11.

[0081] <Second Embodiment>

[0082] In the vacuum pump 100 of the first embodiment, the magnetic retainer 30 is fitted into the step of the housing 11. Figure 7 As shown, in the vacuum pump 100a of the second embodiment, a spacer 40 is fitted in the step of the housing 11. The structure of the other parts of the vacuum pump 100a of the second embodiment is the same as the structure of the vacuum pump 100 of the first embodiment. In the second embodiment, the magnetic retainer 30 is fixed to the portion other than the step of the inner wall of the housing 11. Or the magnetic retainer 30 is integrated with the housing 11.

[0083] The spacers 40 and 45 are components for fixing the stator blade unit 23 to the housing 11. The spacer 40 is the uppermost spacer and is arranged above the axial direction A1 compared to the spacer 45. The spacers 40 and 45 are annular. The outer peripheral surface 41 of the spacer 40 is fitted and arranged in contact with the surface 11a extending in the vertical direction along the step of the inner wall of the housing 11.

[0084] like Figure 8 As shown, the spacer 40 includes an outer peripheral surface 41 and an upper surface 42. In addition, the step difference of the inner wall of the housing 11 includes a surface 11a extending in the up-down direction and a surface 11b extending in the radial direction. The outer peripheral surface 41 of the spacer 40 is fitted in a manner of being in contact with the inner wall surface 11a of the housing 11. In addition, the upper surface 42 of the spacer 40 is in contact with the surface 11b constituting the step difference of the housing 11. At the step difference of the inner wall of the housing 11, a gap S1a is formed between the housing 11 and the spacer 40. If the gap S1a is a closed space, it becomes a gas accumulation, resulting in slow leakage.

[0085] In this embodiment, a groove 411 is formed on the outer peripheral surface 41 of the spacer 40. The groove 411 connects the gap S1a with other spaces inside the housing 11. The other spaces become exhaust paths. Therefore, it is easy to exhaust the gap S1a, thereby suppressing slow air leakage. In detail, the groove 411 is connected to a small gap between the other spacer 45 located on the exhaust downstream side compared to the uppermost spacer 40 and the housing 11 (see Figure 7 ). The gap between the spacer 45 and the housing 11 is connected to the air inlet P12 at the bottom, and is therefore connected to the exhaust path between the turbomolecular pump and the thread groove pump. Therefore, the gas in the gap S1a is discharged to the exhaust path between the turbomolecular pump and the thread groove pump via the groove 411 and the gap between the spacer 45 and the housing 11.

[0086] In the second embodiment, the groove 411 is formed in the spacer 40. The groove may be formed in the housing 11 as in Modification 1A and Modification 1B. In this case, the gap S1a can be easily vented and slow gas leakage can be suppressed as in the second embodiment.

[0087] The vacuum pump 100 and the vacuum pump 100a of the above embodiment are compound pumps that integrate a turbomolecular pump and a thread groove pump. However, the turbomolecular pump may be omitted. That is, the vacuum pump 100 and the vacuum pump 100a may be composed of only the thread groove pump. Conversely, the thread groove pump may be omitted. That is, the vacuum pump 100 and the vacuum pump 100a may be composed of only the turbomolecular pump.

[0088] <Third Embodiment>

[0089] This embodiment is a leak detector 500 using the vacuum pump 100 of the first embodiment or the vacuum pump 100a of the second embodiment. In addition, the vacuum pump 100 here refers to the vacuum pump 100 of the first embodiment or the vacuum pump 100a of the second embodiment.

[0090] like Fig. 9 As shown, the leak detector 500 includes a vacuum pump 100, an analysis tube 200, a roughing pump 300, a test port 401, a calibration standard leak 110, a vacuum gauge 120, valves 101 to 106, and pipes L1 to L5 connecting these.

[0091] The leak detector 500 can be applied to a carrier gas leakage test method of a sample. The test method is either: setting the interior of the sample to a vacuum state and analyzing the carrier gas that enters the sample from the outside; or filling the sample with a carrier gas and analyzing the carrier gas that leaks out of the sample. The carrier gas is preferably helium.

[0092] The test port 401 is connected to the sample 400 or a container containing the sample 400 so as to collect the leaked carrier gas. The test port 401 is connected to the roughing pump 300 via the pipe L1. A roughing valve 103 is disposed in the middle of the pipe L1. The roughing pump 300 is, for example, an oil rotary pump.

[0093] The analysis tube 200 is connected to the first suction port P11 of the vacuum pump 100 through the pipe L5. That is, the analysis tube 200 is exhausted by the vacuum pump 100. The exhaust port P21 of the vacuum pump 100 is connected to the roughing pump 300 through the pipe L4. A foreline valve 106 is arranged in the middle of the pipe L4. That is, the roughing pump 300 is used as an auxiliary pump of the vacuum pump 100.

[0094] The test port 401 is connected to the second air intake port P12 of the vacuum pump 100 via the piping L2 and the test valve 104. In addition, the test port 401 is connected to the second air intake port P13 of the vacuum pump 100 via the piping L3 and the test valve 105. An exhaust path from the first air intake port P11 to the exhaust port P21 is formed inside the vacuum pump 100. The second air intake port P12 and the second air intake port P13 are connected in the middle of the exhaust path. The second air intake port P12 is connected to the upstream side of the exhaust path compared to the other second air intake ports P13. The second air intake port P12 is connected between the turbomolecular pump and the thread groove pump of the vacuum pump 100. The other second air intake ports P13 are connected in the middle of the thread groove pump.

[0095] like Fig. 9 As shown, the pipe L1 is connected with an exhaust valve 101, a calibration valve 102, and a vacuum gauge 120. The calibration valve 102 is connected with a calibration standard leak 110. The calibration standard leak 110 is detachable. The exhaust valve 101 opens the pipe L1 to atmospheric pressure. The vacuum gauge 120 can detect the pressure in the pipe L1.

[0096] Next, a method for checking the leakage of a sample using the leak detector 500 is described. The leak checking method uses a principle called the back-diffusion measurement method. The back-diffusion measurement method is to supply a carrier gas (leak check gas) to the middle or downstream side of the exhaust path of the vacuum pump 100, and to detect the carrier gas back-diffused to the upstream side of the exhaust path using the analysis tube 200 to obtain the leakage amount.

[0097] After starting the leak detector 500, the roughing pump 300, vacuum pump 100 and analysis tube 200 are started. Valve 106 is opened, and other valves 101 to 105 are closed. The analysis tube 200 is evacuated using the vacuum pump 100 to a specific background value (vacuum degree).

[0098] After the test port 401 is covered, the roughing valve 103 is opened, and the pipe L1 is exhausted by the roughing pump 300. After the pipe L1 reaches a specific pressure, the roughing valve 103 is closed, and then the test valve 105 and the calibration valve 102 are opened. As a result, the calibration carrier gas (helium) in the calibration standard leak 110 flows out to the pipe L1, passes through the test valve 105, and reaches the exhaust path of the vacuum pump 100 from the suction port P13, and calibration is performed.

[0099] Next, a leakage check of the sample is performed. The following describes a case where a leakage check is performed using a small container such as a package as a sample. Fill the sample with a carrier gas. Place the sample in a vacuum container connected to the test port 401. Open the roughing valve 103, and exhaust the inside of the pipe L1 through the roughing pump 300. After the inside of the pipe L1 reaches a specific pressure, close the roughing valve 103 and open the test valve 105. The carrier gas leaking from the sample passes through the test valve 105 and reaches the exhaust path inside the vacuum pump 100 through the second air intake port P13 of the vacuum pump 100. The reverse-diffused carrier gas is detected using the analysis tube 200 to measure the leakage amount.

[0100] The above description has been made of the case where the leakage amount is measured using the pipe L3, the test valve 105, and the second air intake port P13. Similarly, if the leakage amount is measured using the pipe L2, the test valve 104, and the second air intake port P12, a more sensitive measurement can be performed.

[0101] In this embodiment, the vacuum pump 100 of the first embodiment or the vacuum pump 100a of the second embodiment is used, so it is easy to exhaust the gap S1 and the gap S1a between the housing 11 and other components (magnetic holder 30 or spacer 40). Therefore, it is possible to reduce the influence of the gas sealed in the gap S1 and the gap S1a on the carrier gas detection in the analysis tube 200. The detection speed of the leaked gas can be increased.

[0102] Although the embodiments of the present disclosure have been described above, the present disclosure is not limited to the embodiments, and various modifications can be made without departing from the gist of the present disclosure. In particular, the embodiments described in this specification can be arbitrarily combined as needed.

[0103] (3) Morphology

[0104] Those skilled in the art will appreciate that the above-described multiple exemplary embodiments are specific examples of the following aspects.

[0105] (Item 1) A vacuum pump of one form comprises:

[0106] A rotor, capable of rotating in a specific direction of rotation;

[0107] a housing for accommodating the rotor; and

[0108] The fixing assembly is arranged to face the inner wall of the housing.

[0109] A gap is formed between the inner wall of the housing and the fixing assembly,

[0110] A groove is formed in one of an inner wall of the housing and the fixing member, and the groove allows the gap to communicate with an exhaust path inside the housing.

[0111] The vacuum pump described in the first item has a gap formed between the housing and a fixing assembly disposed opposite to the inner wall of the housing, and a groove for exhausting the gap is provided in the housing or the fixing assembly, thereby being able to suppress slow gas leakage.

[0112] (Item 2) A vacuum pump according to Item 1, wherein

[0113] The housing includes a step difference, and the step difference includes a surface extending in a radial direction and a surface extending in an axial direction.

[0114] The fixing assembly includes a step difference, and the step difference includes a surface extending along the radial direction and a surface extending along the axial direction.

[0115] The gap is formed between the step of the housing and the step of the fixing component by fitting the step of the housing and the step of the fixing component.

[0116] The vacuum pump described in the second item is constructed by fitting the step of the housing and the step of the fixing member together, so that a gap is easily formed, and slow gas leakage can be suppressed by forming a groove in the housing or the fixing member.

[0117] (Item 3) A vacuum pump according to Item 1 or Item 2, further comprising:

[0118] stator blades, which together with the rotor blades form a turbomolecular pump; and

[0119] A plurality of spacers are provided to clamp the stator blades from above and below in the axial direction to position them.

[0120] The gap communicates with an exhaust path inside the housing via a gap formed between the plurality of spacers and an inner wall of the housing.

[0121] In the vacuum pump described in the third item, the gap between the housing and the fixed assembly is connected to the exhaust path inside the housing via the groove and the gap formed between the spacer and the inner wall of the housing, thereby preventing the gap between the housing and the fixed assembly from accumulating gas and causing slow leakage.

[0122] (Item 4) A vacuum pump according to Item 1 or Item 2, wherein the fixing component is a magnetic retainer, and the magnetic retainer retains the permanent magnet of the permanent magnet magnetic bearing.

[0123] The vacuum pump described in the fourth item includes a magnetic retainer, so that the permanent magnet of the permanent magnet magnetic bearing can be properly retained. In addition, a gap is formed between the housing and the magnetic retainer, and a groove for exhausting the gap is provided in the housing or the magnetic retainer, so that slow leakage can be suppressed.

[0124] (Item 5) A vacuum pump according to Item 4, wherein the groove is formed in the magnetic retainer.

[0125] The vacuum pump described in the fifth aspect has grooves formed in the magnetic retainer, so that processing is easier than forming grooves in the housing.

[0126] (Item 6) A vacuum pump according to Item 5, wherein

[0127] The magnetic retainer includes: a beam extending in a radial direction from the center; and an outer ring portion connected to the beam through the outer side of the beam and connected to the housing.

[0128] The groove is formed in a portion of the outer ring portion connected to the beam.

[0129] The vacuum pump described in Item 6 has a groove formed in the portion connected to the beam having high rigidity. Therefore, when the groove is formed, the magnetic retainer is less likely to be deformed.

[0130] (Item 7) A vacuum pump according to Item 1, wherein

[0131] The rotor comprises rotor blades,

[0132] The vacuum pump further comprises:

[0133] stator blades, which together with the rotor blades form a turbomolecular pump;

[0134] A plurality of spacers are provided to clamp the stator blades from above and below in the axial direction to position them.

[0135] The fixing member is an uppermost spacer among the plurality of spacers.

[0136] According to the vacuum pump described in the seventh aspect, a gap is formed between the housing and the spacer, and a groove for exhausting the gap is provided in the housing or the spacer, so that slow gas leakage can be suppressed.

[0137] (Item 8) The vacuum pump according to Item 7, wherein the groove is formed in the uppermost spacer.

[0138] The vacuum pump described in Item 8 has the groove formed in the spacer, so that processing is easier than forming the groove in the housing.

[0139] (Item 9) A vacuum pump according to Item 1 to Item 4 or Item 7, wherein the groove is formed in the housing.

[0140] The vacuum pump described in Item 9 has a groove formed in the housing, so when the groove is formed in the fixing component, the risk of deformation can be suppressed.

[0141] (Item 10) A leak detector of a type includes:

[0142] A vacuum pump as described in any one of items 1 to 9, comprising a first air intake port, an air exhaust port, and a second air intake port connected to an exhaust path between the first air intake port and the air exhaust port; and

[0143] Analytical tube, leak detection gas,

[0144] The analysis tube is connected to the first air inlet of the vacuum pump.

[0145] The object under test is connected to the second air suction port of the vacuum pump.

[0146] In the leak detector described in the tenth item, the gaps S1 and S1a between the housing and other components can be easily exhausted. Therefore, the influence of the gas sealed in the gaps S1 and S1a on the detection of the carrier gas in the analysis tube 200 can be reduced, and the detection speed of the leaked gas can be increased.

Claims

1. A vacuum pump, wherein: include: A rotor, capable of rotating in a specific direction of rotation; A housing for accommodating the rotor; as well as The fixing assembly is arranged to face the inner wall of the housing. A gap is formed between the inner wall of the housing and the fixing assembly, The housing includes a step difference, and the step difference includes a surface extending in a radial direction and a surface extending in an axial direction. The fixing assembly includes a step difference, and the step difference includes a surface extending along the radial direction and a surface extending along the axial direction. The step difference of the housing and the step difference of the fixing component are fitted with each other, and the gap for gas accumulation is formed between the step difference of the housing and the step difference of the fixing component, that is, between the portion where the radially extending surface of the housing and the axially extending surface intersect, and the portion where the radially extending surface of the fixing component and the axially extending surface intersect, A groove is formed in one of the inner wall of the housing and the fixing member, and the groove allows the gap to communicate with an exhaust path inside the housing and allows the accumulated gas to be exhausted to the exhaust path.

2. The vacuum pump according to claim 1, wherein: The vacuum pump further comprises: stator blades, which together with the rotor blades form a turbomolecular pump; and A plurality of spacers are provided to clamp the stator blades from above and below in the axial direction to position them. The gap communicates with an exhaust path inside the housing via a gap formed between the plurality of spacers and an inner wall of the housing.

3. The vacuum pump according to claim 1, wherein: The fixing component is a magnetic retainer, and the magnetic retainer retains the permanent magnet of the permanent magnet magnetic bearing.

4. The vacuum pump according to claim 3, wherein: The groove is formed in the magnetic retainer.

5. The vacuum pump according to claim 4, wherein: The magnetic retainer includes: a beam extending in a radial direction from the center; and an outer ring portion connected to the beam through the outer peripheral side of the beam and connected to the housing. The groove is formed in a portion of the outer ring portion connected to the beam.

6. The vacuum pump according to claim 1, wherein: The rotor comprises rotor blades, The vacuum pump further comprises: stator blades, which together with the rotor blades form a turbomolecular pump; A plurality of spacers are provided to clamp the stator blades from above and below in the axial direction to position them. The fixing member is an uppermost spacer among the plurality of spacers.

7. The vacuum pump according to claim 6, wherein: The groove is formed in the uppermost spacer.

8. The vacuum pump according to any one of claims 1 to 3 and 6, wherein: The groove is formed in the housing.

9. A leak detector comprising: A vacuum pump according to any one of claims 1 to 8, comprising a first air intake port, an air exhaust port, and a second air intake port connected to an exhaust path between the first air intake port and the air exhaust port; as well as Analytical tube, leak detection gas, The analysis tube is connected to the first air inlet of the vacuum pump. The object under test is connected to the second air suction port of the vacuum pump.

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