Vacuum Pumps and Leak Detectors

Abstract

To prevent gas accumulation from occurring between a casing and a component fixed to the casing in a vacuum pump, and thereby prevent a slow leak from occurring.SOLUTION: A vacuum pump 100 or 100a comprises a rotor 20 capable of rotating in a predetermined rotation direction, a casing 11 housing the rotor 20, and a fixed component 30 or 40 arranged so as to be opposed to an inner wall of the casing 11. A gap S1 or S1a is formed between the inner wall of the casing 11 and the fixed component 30 or 40. A groove 111a, 111b, 311, or 411 for causing the gap S1 or S1a and an exhaust path inside the casing 11 to communicate with each other is formed in the inner wall of the casing 11 or the fixed component 30 or 40.SELECTED DRAWING: Figure 2

Description

[Technical field]

[0001] The present disclosure relates to vacuum pumps and leak detectors. [Background technology]

[0002] Turbo molecular pumps are used as vacuum pumps for ultra-high vacuums and for leak detectors. A turbo molecular pump houses a rotor inside a casing and performs evacuation by rotating the rotor at tens of thousands of revolutions per minute.

[0003] In a rotor that rotates at high speed, if a sealed space occurs at the assembly of parts, there is a problem that a slow leak occurs in which gas trapped in the sealed space gradually leaks out. Patent Document 1 discloses a means for eliminating the slow leak by eliminating the sealed space in the rotor part. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2020-197127 A Summary of the Invention [Problem to be solved by the invention]

[0005] In a vacuum pump, gas may accumulate in the casing and in the parts fixed to the casing, which may cause a slow leak. The present disclosure aims to provide a means for eliminating such gas accumulation and thus eliminating a slow leak. [Means for solving the problem]

[0006] The vacuum pump of the present disclosure comprises: A rotor that is rotatable in a predetermined direction of rotation; A casing that houses the rotor; a fixed part disposed to face an inner wall of the casing, A gap is formed between the inner wall of the casing and the fixed component, A groove is formed in either the inner wall of the casing or the fixed component, which connects the gap with an exhaust path inside the casing.

[0007] The leak detector of the present disclosure comprises: A vacuum pump according to the present disclosure, comprising: a first intake port, an exhaust port, and a second intake port connected to an exhaust path between the first intake port and the exhaust port; an analytical tube for detecting a gas for leak testing; Equipped with the analytical tube is connected to a first inlet of the vacuum pump; The device under test is connected to a second inlet of the vacuum pump. Effect of the Invention

[0008] In the vacuum pump of the present disclosure, a gap is formed between the casing and a fixed component that is fitted into the inner wall of the casing, and a groove for evacuating this gap is provided in the casing or the fixed component, thereby suppressing slow leaks.

[0009] In addition, because the leak detector of the present disclosure suppresses slow leaks from the vacuum pump, the time it takes for the leak rate to drop to near background in a single test is shortened, allowing for rapid leak checks. [Brief description of the drawings]

[0010] [Figure 1] 1 is a cross-sectional view of a vacuum pump 100 according to a first embodiment. [Diagram 2] 1 is an enlarged view of a step on the inner wall of the casing 11 in the first embodiment and a fitting portion of the magnet holder 30. FIG. [Diagram 3] FIG. 2 is a perspective view of a magnet holder 30 according to the first embodiment. [Figure 4] FIG. 2 is a top view of a portion of the magnet holder 30 of the first embodiment. [Diagram 5] 13 is an enlarged view of a step on the inner wall of casing 11 of modification 1A and a fitting portion of magnet holder 30. FIG. [Figure 6] 13 is an enlarged view of a step on the inner wall of the casing 11 of the modified example 1B and a fitting portion of the magnet holder 30. FIG. [Figure 7] FIG. 4 is a cross-sectional view of a vacuum pump 100a according to a second embodiment. [Figure 8] 13 is an enlarged view of a step on the inner wall of the casing 11 in the second embodiment and a fitting portion of the spacer 40. FIG. [Figure 9] FIG. 13 is a diagram showing a configuration of a leak detector 500 according to a third embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0011] First Embodiment 1, the vacuum pump 100 of the first embodiment includes a housing 10, a rotor 20, a motor 28, a magnet holder 30, a multi-stage stator blade unit 23, a stator cylindrical portion 26, and bearings 51, 52, and 55. The housing 10 is composed of a casing 11 and a base 12. The housing 10 accommodates the rotor 20, the motor 28, the magnet holder 30, the multi-stage stator blade unit 23, the stator cylindrical portion 26, and bearings 51, 52, and 55.

[0012] As shown in Fig. 1, the housing 10 has a first intake port P11, second intake ports P12, P13, and an exhaust port P21. An exhaust target device having an exhaust target space is connected to the intake port P11. An auxiliary pump is connected to the exhaust port. An exhaust path is formed in the internal space of the housing 10 from the first intake port P11 to the exhaust port P21. A plurality of second intake ports P12, P13 are connected to this exhaust path. When the vacuum pump 100 is used as a leak detector, piping from a test specimen is connected to each of the plurality of second intake ports P12, P13.

[0013] The rotor 20 includes a shaft 27 , a plurality of rotor blade units 21 , and a rotor cylindrical portion 25 .

[0014] The shaft 27 extends in an axial direction A1 of the rotor 20. In the following description, in the axial direction A1, the direction from the casing 11 to the base 12 is defined as a downward direction, and the opposite direction is defined as an upward direction.

[0015] Shaft 27 is rotatably fixed to housing 10 by bearings 51 and 52, and a magnetic bearing 55. More specifically, an upper portion of shaft 27 is fixed to magnet holder 30 by bearing 51 and magnetic bearing 55, and magnet holder 30 is fixed to casing 11. A lower portion of shaft 27 is fixed to base 12 by bearing 52.

[0016] The motor 28 rotates the rotor 20. The motor 28 includes a motor rotor 28a and a motor stator 28b. The motor rotor 28a is attached to the shaft 27. The motor stator 28b is attached to the base 12. The motor stator 28b is disposed to face the motor rotor 28a.

[0017] The multiple rotor blade units 21 are each connected to the shaft 27. The multiple stages of rotor blade units 21 are arranged at intervals from one another in the axial direction A1. Each rotor blade unit 21 includes multiple rotor blades 22. Although not shown, the multiple rotor blades 22 each extend radially from the shaft 27 as a center. In the drawings, only one of the multiple rotor blade units 21 and one of the multiple rotor blades 22 are labeled with a reference symbol, and the reference symbols of the other rotor blade units 21 and other rotor blades 22 are omitted.

[0018] The multiple stages of stator blade units 23 are sandwiched between two spacers 45 arranged above and below, and stacked on the inner surface of the casing 11. The multiple stages of stator blade units 23 are arranged at intervals from each other in the axial direction A1. The multiple stages of stator blade units 23 are respectively arranged between the multiple stages of rotor blade units 21. Each of the stator blade units 23 includes a plurality of stator blades 24. Although not shown in the figure, the multiple stages of stator blades 24 each extend radially from the shaft 27 as a center.

[0019] A turbomolecular pump is constituted by the multiple stages of rotor blade units 21 and the multiple stages of stator blade units 23. In the drawings, only one of the multiple stator blade units 23 and one of the multiple stator blades 24 are labeled with a reference symbol, and the reference symbols of the other stator blade units 23 and other stator blades 24 are omitted.

[0020] The rotor cylindrical portion 25 is disposed below the rotor blade unit 21. The rotor cylindrical portion 25 extends in the axial direction A1.

[0021] The stator cylindrical portion 26 is disposed radially outward of the rotor cylindrical portion 25. The stator cylindrical portion 26 is fixed to the housing 10. The stator cylindrical portion 26 is disposed facing the rotor cylindrical portion 25 in the radial direction of the rotor cylindrical portion 25. A spiral groove is provided on the inner peripheral surface of the stator cylindrical portion 26. The rotor cylindrical portion 25 and the stator cylindrical portion 26 constitute a thread groove pump.

[0022] The magnet holder 30 holds the permanent magnets on the inner circumference side of the magnetic bearing 55 and positions the inner circumference side permanent magnets in the radial and axial directions. The magnet holder 30 is arranged above the shaft 27 of the rotor 20 by fitting into the inner wall of the casing 11. As shown in FIG. 3, the magnet holder 30 includes a center portion 33, an outer ring portion 31, and a beam 32 connecting the center portion 33 and the outer ring portion 31. The outer ring portion 31 is fitted into the inner wall of the casing 11. The permanent magnets on the inner circumference side of the magnetic bearing 55 are fixed to the center portion 33. Meanwhile, the permanent magnets on the outer circumference side of the magnetic bearing 55 are fixed to the rotor 20. The rotor 20 is levitated to a predetermined position upward in the axial direction A1 by the repulsive force due to the magnetic force between the permanent magnets on the inner circumference side and the permanent magnets on the outer circumference side of the magnetic bearing 55.

[0023] As shown in FIG. 3, the outer ring portion 31 of the magnet holder 30 has a step. The step is composed of an outer peripheral surface 31a and a radial surface 31b. Also, the inner wall of the casing 11 has a step. As shown in FIG. 2, the step is composed of a surface 11a extending in the vertical direction and a surface 11b extending in the radial direction. The outer peripheral surface 31a of the magnet holder 30 is fitted so as to be in contact with the inner wall surface 11a of the casing 11. Also, the surface 31b of the magnet holder 30 is in contact with the surface 11b constituting the step of the casing 11. Due to this configuration, a gap S1 is formed between the casing 11 and the magnet holder 30 at the step of the inner wall of the casing 11. If the gap S1 is a closed space, it will become a gas trap and cause a slow leak.

[0024] In this embodiment, a groove 311 is formed on the outer peripheral surface 31a of the outer ring portion 31 of the magnet holder 30. The groove 311 connects the gap S1 to other spaces inside the casing 11. The other spaces serve as exhaust paths. Therefore, the gap S1 is easily exhausted, and slow leak is suppressed. In detail, the groove 311 connects to a small gap (see FIG. 1) that exists between the spacer 45 and the casing 11. The gap that exists between the spacer 45 and the casing 11 connects to the intake port P12 at the bottom, and therefore connects to the exhaust path between the turbo molecular pump and the thread groove pump. Therefore, the gas in the gap S1 is exhausted to the exhaust path between the turbo molecular pump and the thread groove pump via the groove 311 and the gap that exists between the spacer 45 and the casing 11.

[0025] As shown in Fig. 4, the groove 311 is preferably formed in a portion of the outer ring portion 31 that connects to the beam 32. This portion has high rigidity and is less likely to be distorted due to the beam 32 when processing the groove 311. If the magnet holder 30 is distorted, the rotation axis of the rotor 20 will undesirably shift from the center. The groove 311 is preferably disposed between radii R11 and R22 (the radius refers to the straight line connecting the end and the center of the outer ring portion 31) that pass through the outer ends of the radii R1 and R2 of the connections between the beam 32 and the outer ring portion 31.

[0026] <Modification 1A of the First Embodiment> In the first embodiment, as shown in Fig. 2, a groove 311 that connects the gap S1 between the casing 11 and the magnet holder 30 to the exhaust path inside the casing 11 is formed in the magnet holder 30. In the modified example 1A, as shown in Fig. 5, the groove 111a is formed in the surface 11a extending in the up-down direction of the casing 11. The rest of the configuration of the modified example 1A is the same as that of the first embodiment. In the case of the modified example 1A, the gas that accumulates in the gap S1 between the casing 11 and the magnet holder 30 is easily discharged to the exhaust path via the groove 111a, and the occurrence of a slow leak is suppressed.

[0027] <Modification 1B of the First Embodiment> In the modified example 1A, the groove 111a is formed on the surface 11a extending in the vertical direction of the casing 11. In contrast, in the modified example 1B, as shown in FIG. 6, the groove 111b is formed on the surface 11b extending in the radial direction of the step of the casing 11. The other configurations of the modified example 1B are the same as those of the first embodiment. In the case of the modified example 1B, the gas accumulated in the gap S1 between the casing 11 and the magnet holder 30 is easily discharged to the exhaust path via the groove 111b, and the occurrence of slow leak is suppressed. In detail, the groove 111 communicates with the gap existing between the magnet holder 30 and the casing 11 in the upper part of the axial direction. The gap existing between the magnet holder 30 and the casing 11 in the upper part of the axial direction communicates with the space above the magnet holder 30. Therefore, the gas in the gap S1 is exhausted to the exhaust path upstream of the turbo molecular pump via the groove 311 and the gap existing between the magnet holder 30 and the casing 11.

[0028] <Second embodiment> In the vacuum pump 100 of the first embodiment, the magnet holder 30 is fitted into the step of the casing 11. In contrast, in the vacuum pump 100a of the second embodiment, as shown in FIG. 7, a spacer 40 is fitted into the step of the casing 11. The configuration of other parts of the vacuum pump 100a of the second embodiment is the same as that of the vacuum pump 100 of the first embodiment. In the second embodiment, the magnet holder 30 is fixed to a part of the inner wall of the casing 11 other than the step. Alternatively, the magnet holder 30 is integrated with the casing 11.

[0029] The spacers 40 and 45 are components for fixing the stator blade unit 23 to the casing 11. The spacer 40 is the uppermost spacer and is disposed above the spacer 45 in the axial direction A1. The spacers 40 and 45 are ring-shaped. The outer peripheral surface 41 of the spacer 40 is disposed so as to be fitted in contact with a surface 11a of a step in the inner wall of the casing 11, the surface 11a extending in the vertical direction.

[0030] As shown in FIG. 8, the spacer 40 has an outer peripheral surface 41 and an upper surface 42. The step of the inner wall of the casing 11 is composed of a surface 11a extending in the vertical direction and a surface 11b extending in the radial direction. The outer peripheral surface 41 of the spacer 40 is fitted to the inner wall surface 11a of the casing 11 so as to be in contact with the surface 11b constituting the step of the casing 11. At the step of the inner wall of the casing 11, a gap S1a is formed between the casing 11 and the spacer 40. If the gap S1a is a closed space, it will become a gas trap and cause a slow leak.

[0031] 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 to another space inside the casing 11. The other space serves as an exhaust path. Therefore, the gap S1a is easily exhausted, and slow leakage is suppressed. In detail, the groove 411 connects to a small gap (see FIG. 7) existing between the casing 11 and another spacer 45 located downstream of the uppermost spacer 40 in the exhaust direction. The gap existing between the spacer 45 and the casing 11 connects to the intake port P12 at the bottom, and therefore connects to the exhaust path between the turbo molecular pump and the thread groove pump. Therefore, the gas in the gap S1a is exhausted to the exhaust path between the turbo molecular pump and the thread groove pump via the groove 411 and the gap existing between the spacer 45 and the casing 11.

[0032] In the second embodiment, the groove 411 is formed in the spacer 40. The groove may be formed in the casing 11, similar to Modifications 1A and 1B. In this case, the gap S1a is easily evacuated, and slow leak is suppressed, similar to the second embodiment.

[0033] The vacuum pumps 100 and 100a according to the above embodiments are composite pumps in which a turbomolecular pump and a thread groove pump are integrated. However, the turbomolecular pump may be omitted. That is, the vacuum pumps 100 and 100a may be composed of only a thread groove pump. Conversely, the thread groove pump may be omitted. That is, the vacuum pumps 100 and 100a may be composed of only a turbomolecular pump.

[0034] <Third embodiment> 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. Note that the vacuum pump 100 here refers to the vacuum pump 100 of the first embodiment or the vacuum pump 100a of the second embodiment.

[0035] As shown in FIG. 9, the leak detector 500 includes a vacuum pump 100, an analytical 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 them.

[0036] The leak detector 500 can be applied to a carrier gas leak test method for a test object. The test method is either to put the inside of the test object into a vacuum state and analyze the carrier gas that enters the inside of the test object from the outside, or to fill the inside of the test object with carrier gas and analyze the carrier gas that leaks out to the outside of the test object. The carrier gas is preferably helium gas.

[0037] The test port 401 is connected to the test specimen 400 or to a container that contains the test specimen 400 so that leaked carrier gas can be collected. The test port 401 is connected to the roughing pump 300 by a 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.

[0038] The analytical tube 200 is connected to a first intake port P11 of the vacuum pump 100 by a pipe L5. That is, the analytical tube 200 is evacuated by the vacuum pump 100. An exhaust port P21 of the vacuum pump 100 is connected to a roughing pump 300 via a pipe L4. A foreline valve 106 is disposed in the middle of the pipe L4. That is, the roughing pump 300 is used as a backup pump for the vacuum pump 100.

[0039] The test port 401 is connected to the second intake port P12 of the vacuum pump 100 via the pipe L2 and the test valve 104. The test port 401 is also connected to the second intake port P13 of the vacuum pump 100 via the pipe L3 and the test valve 105. Inside the vacuum pump 100, an exhaust path is formed from the first intake port P11 to the exhaust port P21. The second intake ports P12 and P13 are connected to the middle of the exhaust path. The second intake port P12 is connected to the upstream side of the exhaust path relative to another second intake port P13. The second intake port P12 is connected between the turbo molecular pump and the thread groove pump of the vacuum pump 100. The other second intake port P13 is connected to the middle of the thread groove pump.

[0040] As shown in Fig. 9, a vent valve 101, a calibration valve 102, and a vacuum gauge 120 are connected to the pipe L1. A calibration standard leak 110 is connected to the calibration valve 102. The calibration standard leak 110 is detachable. The vent valve 101 opens the pipe L1 to atmospheric pressure. The vacuum gauge 120 can detect the pressure inside the pipe L1.

[0041] Next, a method for checking leaks in a test specimen using the leak detector 500 will be described. The leak check method uses a principle called the reverse diffusion measurement method. The reverse diffusion measurement method involves supplying a carrier gas (gas for leak inspection) to the middle or downstream side of the exhaust path of the vacuum pump 100, detecting the carrier gas that has diffused reversely through the exhaust path to the upstream side with the analysis tube 200, and determining the amount of leak.

[0042] When the leak detector 500 is started, the roughing pump 300, the vacuum pump 100, and the analytical tube 200 are started. The valve 106 is opened, and the other valves 101 to 105 are closed. The inside of the analytical tube 200 is evacuated using the vacuum pump 100 until a predetermined background value (degree of vacuum) is reached.

[0043] After the test port 401 is covered, the roughing valve 103 is opened and the pipe L1 is evacuated by the roughing pump 300. When the pipe L1 reaches a predetermined 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 gas) in the calibration standard leak 110 flows into the pipe L1, passes through the test valve 105, and reaches the exhaust path of the vacuum pump 100 from the intake port P13, and calibration is performed.

[0044] Next, a leak test is performed on the test specimen. A case where a leak test is performed on a small container such as a package as the test specimen will be described. The test specimen is filled with carrier gas. The test specimen is placed in a vacuum vessel connected to the test port 401. The roughing valve 103 is opened, and the inside of the pipe L1 is evacuated by the roughing pump 300. When the inside of the pipe L1 reaches a predetermined pressure, the roughing valve 103 is closed, and the test valve 105 is opened. The carrier gas leaked from the test specimen reaches the exhaust path in the vacuum pump 100 via the test valve 105 and the second intake port P13 of the vacuum pump 100. The back-diffused carrier gas is detected by the analysis tube 200, and the amount of leakage is measured.

[0045] The above describes a case where the amount of leakage is measured using the pipe L3, the test valve 105, and the second intake port P13. In a similar manner, if the amount of leakage is measured using the pipe L2, the test valve 104, and the second intake port P12, a more sensitive measurement can be performed.

[0046] In this embodiment, since the vacuum pump 100 of the first embodiment or the vacuum pump 100a of the second embodiment is used, the gaps S1, S1a between the casing 11 and other parts (the magnet holder 30 or the spacer 40) are easily evacuated. Therefore, the influence of the gas trapped in the gaps S1, S1a on the carrier gas detection in the analysis tube 200 can be reduced. The detection speed of the leak gas can be increased.

[0047] Although several embodiments of the present disclosure have been described above, the present disclosure is not limited to the above-mentioned embodiments, and various modifications are possible without departing from the gist of the present disclosure. In particular, several embodiments described in this specification can be arbitrarily combined as necessary. (3) Description It will be appreciated by those skilled in the art that the exemplary embodiments described above are examples of the following aspects.

[0048] (Item 1) A vacuum pump according to one aspect comprises: A rotor that is rotatable in a predetermined direction of rotation; A casing that houses the rotor; a fixed part disposed to face an inner wall of the casing, A gap is formed between the casing, the inner wall, and the fixed part, A groove is formed in either the inner wall of the casing or the fixed component, which connects the gap with an exhaust path inside the casing.

[0049] In the vacuum pump described in paragraph 1, a gap is formed between the casing and the fixed component arranged opposite the inner wall of the casing, and a groove for evacuating this gap is provided in the casing or the fixed component, so that slow leak can be suppressed.

[0050] (2) In the vacuum pump according to the first aspect, The casing has a step having a surface extending in a radial direction and a surface extending in an axial direction, the stationary component has a step having a radially extending surface and an axially extending surface; The gap is formed between the step of the casing and the step of the fixed part by fitting the step of the casing and the step of the fixed part together.

[0051] The vacuum pump described in paragraph 2 is configured such that a step in the casing and a step in the fixed component are fitted together, so that gaps are easily formed, and slow leaks can be suppressed by forming grooves in the casing or the fixed component.

[0052] (Item 3) In the vacuum pump according to item 1 or 2, a stator blade which constitutes a turbomolecular pump together with the rotor blade; a plurality of spacers that sandwich and position the stator blades from above and below in the axial direction; Further equipped with The gap communicates with an exhaust path inside the casing via gaps formed between the plurality of spacers and an inner wall of the casing.

[0053] In the vacuum pump described in paragraph 3, the gap between the casing and the fixed part communicates with the exhaust path inside the casing through the groove and the gap formed between the spacer and the inner wall of the casing, thereby preventing the gap between the casing and the fixed part from becoming a gas trap and causing a slow leak.

[0054] (Item 4) In the vacuum pump according to item 1 or 2, the fixed part is a magnet holder that holds a permanent magnet of a permanent magnet magnetic bearing.

[0055] The vacuum pump described in paragraph 4 is provided with a magnet holder, so that the permanent magnets of the permanent magnet magnetic bearing can be appropriately held. Also, a gap is formed between the casing and the magnet holder, and a groove for exhausting this gap is provided in the casing or the magnet holder, so that slow leak can be suppressed.

[0056] (Item 5) In the vacuum pump as described in item 4, the groove is formed in the magnet holder.

[0057] In the vacuum pump described in item 5, the groove is formed in the magnet holder, and therefore, processing is easier than forming a groove in the casing.

[0058] (Item 6) In the vacuum pump according to item 5, the magnet holder has a beam extending radially from a center, and an outer ring portion connected to the beam on an outer side of the beam and in contact with the casing; The groove is formed in a portion of the outer ring portion that connects to the beam.

[0059] In the vacuum pump described in item 6, a groove is formed in the portion connected to the highly rigid beam, so that the magnet holder is less likely to be distorted when the groove is formed.

[0060] (Item 7) In the vacuum pump according to item 1, The rotor comprises rotor blades; The vacuum pump is a stator blade forming together with said rotor blade a turbomolecular pump; a plurality of spacers that sandwich and position the stator blades from above and below in the axial direction; Further equipped with The fixed component is an uppermost spacer among the plurality of spacers.

[0061] According to the vacuum pump described in the seventh aspect, a gap is formed between the casing and the spacer, and a groove for exhausting this gap is provided in the casing or the spacer, so that slow leak can be suppressed.

[0062] (Item 8) In the vacuum pump as described in item 7, the groove is formed in the uppermost spacer.

[0063] In the vacuum pump described in item 8, the groove is formed in the spacer, and therefore, processing is easier than forming a groove in the casing.

[0064] (Item 9) In the vacuum pump according to items 1 to 4 or 7, the groove is formed in the casing.

[0065] In the vacuum pump described in item 9, the groove is formed in the casing, and therefore the risk of distortion occurring when forming a groove in the fixed component can be reduced.

[0066] (Item 10) A leak detector according to one aspect comprises: A vacuum pump according to any one of claims 1 to 9, comprising a first intake port, an exhaust port, and a second intake port connected to an exhaust path between the first intake port and the exhaust port; an analytical tube for detecting a gas for leak testing; Equipped with the analytical tube is connected to a first inlet of the vacuum pump; The device under test is connected to a second inlet of the vacuum pump.

[0067] In the leak detector described in paragraph 10, the gaps S1 and S1a between the casing and other components are easily evacuated. Therefore, it is possible to reduce the effect of gas trapped in the gaps S1 and S1a on carrier gas detection in the analytical tube 200. It is possible to increase the detection speed of leak gas. [Explanation of symbols]

[0068] 10. Chassis 11 Casing 12 Base 20 Rotors 21 Rotor blade unit 22 Rotor blade 23 Stator blade unit 24 Stator blade 25 Rotor cylinder 26 Stator cylinder 27 Shaft 28 Motor 30 Magnet holder 31 Outer ring of magnet holder 32 Magnet holder beam 40 Spacer 100 Vacuum Pump 200 analysis tube 300 Roughing Pump 400 specimens 111a, 111b, 311, 411 groove P11 First air intake P12, P13 2nd air intake P21 Exhaust port R1, R2 R section R11, R22 radius S1, S1a Gap

Claims

1. A rotor that is rotatable in a predetermined direction of rotation; A casing that houses the rotor; a fixed part disposed to face an inner wall of the casing, A gap is formed between the inner wall of the casing and the fixed component, The casing has a step having a surface extending in a radial direction and a surface extending in an axial direction, the stationary component has a step having a radially extending surface and an axially extending surface; When the step of the casing and the step of the fixed part are fitted together, the gap serving as a gas reservoir is formed between the step of the casing and the step of the fixed part, at a portion where a surface extending in the radial direction of the casing intersects with a surface extending in the axial direction of the casing, and at a portion where a surface extending in the radial direction of the fixed part intersects with a surface extending in the axial direction of the casing, A groove is formed in either the inner wall of the casing or the fixed component, the groove communicating the gap with an exhaust path inside the casing and exhausting the gas accumulation to the exhaust path. Vacuum pump.

2. The vacuum pump is a stator blade which constitutes a turbomolecular pump together with the rotor blade; a plurality of spacers that sandwich and position the stator blades from above and below in the axial direction; Further equipped with 2. The vacuum pump according to claim 1, wherein the gap communicates with an exhaust path inside the casing via gaps formed between the plurality of spacers and an inner wall of the casing.

3. The fixed component is a magnet holder that holds a permanent magnet of a permanent magnet magnetic bearing.

2. A vacuum pump as claimed in claim 1.

4. The groove is formed in the magnet holder.

4. A vacuum pump according to claim 3.

5. the magnet holder has a beam extending radially from a center, and an outer ring portion connected to the beam on an outer periphery side of the beam and in contact with the casing, The groove is formed in a portion of the outer ring portion that is connected to the beam.

5. A vacuum pump according to claim 4.

6. The rotor comprises rotor blades; The vacuum pump is a stator blade forming, together with the rotor blade, a turbomolecular pump; a plurality of spacers that sandwich and position the stator blades from above and below in the axial direction; Further equipped with The fixed component is an uppermost spacer among the plurality of spacers.

2. A vacuum pump as claimed in claim 1.

7. The groove is formed in the uppermost spacer.

7. A vacuum pump according to claim 6.

8. The groove is formed in the casing. A vacuum pump according to any one of claims 1 to 3 or 6.

9. 9. A vacuum pump according to claim 1, comprising: a first intake port, an exhaust port, and a second intake port connected to an exhaust path between the first intake port and the exhaust port; an analytical tube for detecting a gas for leak testing; Equipped with the analytical tube is connected to a first inlet of the vacuum pump; The test object is connected to a second intake port of the vacuum pump. Leak detector.

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