vacuum pump

Abstract

The present invention provides a vacuum pump capable of suppressing deformation of the stator in the vertical direction. The vacuum pump (1) includes: a rotor (4) housed in a housing (2) and driven to rotate; multi-stage rotor blades (22) disposed on the rotor (4); and a multi-stage stator (5) disposed between the multi-stage rotor blades (22). The stator (5) has an inner peripheral rib (51), an outer peripheral rib (53), and stator blades (55) connecting the inner peripheral ribs (51) and the outer peripheral ribs (53), and is housed in the housing (2) with the outer peripheral ribs (53) held by spacers (31). At least a portion of the outer peripheral ribs (53) of the stator (5) is provided with a deformation-allowing portion (57) that allows radial deformation of the inner peripheral ribs (51) and / or the stator blades (55).

Description

Technical Field

[0001] This invention relates to a vacuum pump. Prior Technology

[0002] Vacuum pumps include those comprising a rotor with rotor blades and a stator disposed between the rotor blades (see, for example, Patent Document 1). In such vacuum pumps, the rotor blades are moved relative to the stator blades disposed on the stator by rotating the rotor, thereby drawing gas from the interior of the exhaust device and discharging the drawn gas to the outside. [Existing technical documents] [Patent Literature]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 2021-139361 Summary of the Invention

[0004] [The problem that the invention aims to solve]

[0005] In the aforementioned vacuum pumps, for example, to suppress the accumulation of byproducts inside the pump, the stator temperature is sometimes adjusted to a high temperature. Furthermore, even without temperature adjustment, the stator can sometimes become hot due to the high-speed rotation of the rotor or the load of the exhaust gas. In conventional vacuum pumps, due to the temperature fluctuation of the stator caused by temperature adjustments, the stator may deform in the vertical direction (i.e., the direction close to the rotor blades), causing contact between the stator and rotor blades. If the stator contacts the rotor blades, problems such as the vacuum pump malfunctioning or damage to the stator and / or rotor blades may occur.

[0006] Therefore, the purpose of this invention is to suppress deformation in the direction of the stator's rotation axis, so that the vacuum pump can operate safely. [Methods for solving problems]

[0007] One embodiment of the vacuum pump of the present invention includes a rotor, multi-stage rotor blades, and a multi-stage stator. The rotor is housed in a housing and is driven to rotate. The multi-stage rotor blades are disposed on the rotor. The multi-stage stator is arranged between the multi-stage rotor blades. Each stator has an inner circumferential rib, an outer circumferential rib, and stator blades. The stator blades connect the inner circumferential ribs to the outer circumferential ribs. Each stator is housed in the housing in a state where its outer circumferential ribs are held by spacers. At least a portion of the outer circumferential ribs of the stator is provided with a deformation-allowing portion that allows radial deformation of the inner circumferential ribs and / or the stator blades. [The effects of the invention]

[0008] In one embodiment of the vacuum pump of the present invention, at least a portion of the outer peripheral ribs of the stator is provided with a deformation-allowing portion that allows radial deformation of the inner peripheral ribs and / or stator blades. Therefore, even if the outer peripheral ribs are held in place by spacers and thus difficult to deform radially, the inner peripheral ribs and / or stator blades can easily deform radially. As a result, for example, in the event of temperature fluctuations in the vacuum pump, the inner peripheral ribs and / or stator blades can deform radially, thereby suppressing deformation of the inner peripheral ribs and / or stator blades towards the rotor blades. Thus, for example, even in the event of temperature fluctuations in the vacuum pump, the stator will not come into contact with the rotor blades, allowing the vacuum pump to operate safely. Simple Explanation of the Diagram

[0009] Figure 1 is a cross-sectional view of the vacuum pump. Figure 2 is an overall view of the stator assembly. Figure 3 is a cross-sectional view of the part of the stator component with a deformation allowance. Figure 4 is a cross-sectional view of the deformation-allowing section with grooves. Figure 5 is a cross-sectional view of the deformation-allowing section with a hollow part. Figure 6 is a diagram showing an example of a through section, groove, or hollow section other than a circle. Implementation

[0010] The vacuum pump will now be described using Figure 1. Figure 1 is a cross-sectional view of the vacuum pump 1. The vacuum pump 1 includes a housing 2, a base 3, a rotor 4, and a multi-stage stator 5.

[0011] The housing 2 includes a first end 11, a second end 12, and a first internal space S1. An intake port 13 is provided at the first end 11. The intake port 13 is connected to the interior of the exhaust device in a manner that allows gas flow. The first internal space S1 communicates with the intake port 13. The second end 12 is located on the opposite side of the first end 11 in the axial direction of the rotor 4 (hereinafter referred to as "axial direction A1"). The second end 12 is connected to a base 3. The base 3 includes a base end 14. The base end 14 is connected to the second end 12 of the housing 2. The base 3 is, for example, an aluminum component.

[0012] The rotor 4 is housed within the internal space of the housing 2. The rotor 4 includes a shaft 21. The shaft 21 extends along the axial direction A1. The shaft 21 is rotatably housed in the base 3. A thrust disk 21A is provided at the lower part of the shaft 21. Furthermore, a target 21B is screwed at the lower end of the shaft 21.

[0013] The rotor 4 includes multi-stage rotor blades 22 and a rotor cylindrical portion 23. The multi-stage rotor blades 22 are each inclined relative to the axial direction A1 and connected to the shaft 21. The multi-stage rotor blades 22 are arranged at intervals along the axial direction A1. Although not shown in the figure, the multi-stage rotor blades 22 extend radially about the shaft 21. Furthermore, in the figure, only one symbol for each of the multi-stage rotor blades 22 is used, omitting the symbols for the other rotor blades 22. The rotor cylindrical portion 23 is positioned below the multi-stage rotor blades 22. The rotor cylindrical portion 23 extends along the axial direction A1.

[0014] The multi-stage stators 5 are respectively disposed on the base 3 via spacers 31. When the housing 2 is fixed to the base 3, the stacked spacers 31 are clamped between the base 3 and the housing 2, and the outer peripheral ribs 53 (Fig. 2) of the stators 5 are also clamped by the spacers 31. Thus, the multi-stage stators 5 are housed in the housing 2 in a state where they are spaced apart from each other in the axial direction A1. Specifically, each stator 5 is housed in the housing 2 with its outer peripheral ribs clamped by two spacers 31. That is, by clamping the outer peripheral ribs of each stator 5 by two spacers 31, two adjacent stators 5 are arranged at a predetermined interval within the housing 2.

[0015] The multi-stage stators 5 are respectively arranged between the multi-stage rotor blades 22. Specifically, the stator blades 55 (Fig. 2) of each stator 5 are arranged facing each other with the adjacent rotor blades 22.

[0016] The stator 5 has a circular shape along the internal space of the housing 2. The stator 5 includes a plurality of stator components 5a that divide the circular shape. In this embodiment, the stator 5 includes two stator components 5a. That is, in this embodiment, the stator component 5a has a semi-circular shape. In addition, the stator 5 may also include two or more stator components 5a in a fan shape, or it may include a single stator component 5a in a circular shape.

[0017] The vacuum pump 1 includes a threaded stator 6. The threaded stator 6 is fixed in contact with the base 3. The threaded stator 6 is arranged facing the outer peripheral surface of the rotor cylindrical portion 23 with a small gap in the radial direction. A helical groove is provided on the inner peripheral surface of the threaded stator 6 facing the rotor cylindrical portion 23.

[0018] As shown in Figure 1, an exhaust space S2 is formed further downstream of the exhaust downstream end of the rotor cylindrical portion 23 and the threaded stator 6. The exhaust target gas discharged from the exhaust target device is guided into the exhaust space S2. The exhaust space S2 communicates with the exhaust port 15. The exhaust port 15 is provided on the base 3. Another vacuum pump (not shown) is connected to the exhaust port 15. Furthermore, the exhaust downstream side refers to the side closer to the exhaust space S2 in the axial direction A1. Additionally, the exhaust downstream direction refers to the direction facing the exhaust space S2.

[0019] The vacuum pump 1 includes bearings 44A and 44E, magnetic bearings 44B to 44D, and a motor 45. Bearings 44A and 44E are mounted on the base 3 at the location where the shaft 21 is housed. Bearings 44A and 44E support the shaft 21 in a rotatable manner. Bearings 44A and 44E are ball bearings. Magnetic bearings 44B to 44D are bearings that use magnetic force to support the shaft 21. Specifically, magnetic bearings 44B and 44C are radial magnetic bearings that support the shaft 21 radially. Magnetic bearing 44D is a thrust magnetic bearing that supports the shaft 21 axially.

[0020] Motor 45 drives rotor 4 to rotate. Motor 45 includes motor rotor 45A and motor stator 45B. Motor rotor 45A is mounted on shaft 21. Motor stator 45B is mounted on base 3. Motor stator 45B is arranged facing motor rotor 45A.

[0021] In vacuum pump 1, the multi-stage rotor blades 22 and the multi-stage stator 5 (stator blades) constitute a turbomolecular pump section. Additionally, the rotor cylindrical section 23 and the threaded stator 6 constitute a grooved pump section. In vacuum pump 1, the rotor 4 is rotated by the motor 45, and the exhaust gas flows from the interior of the exhaust device through the intake port 13 to the first internal space S1. The exhaust gas in the first internal space S1 is guided to the exhaust space S2 by passing through the turbomolecular pump section and the grooved pump section. The exhaust gas in the exhaust space S2 is discharged from the exhaust port 15. As a result, the interior of the exhaust device installed at the intake port 13 becomes a high vacuum state.

[0022] A heater 71 and cooling water piping are provided on the outer wall of the base 3 for controlling the temperature of the base 3. The temperature of the base 3 is detected by a temperature sensor 72. Based on the temperature detected by the temperature sensor 72, the temperature of the base 3 is controlled by balancing the heating of the base 3 by the heater 71 and the cooling by the cooling water flowing through the cooling water piping.

[0023] The specific structure of the stator 5 (stator component 5a) will now be explained using Figure 2. Figure 2 is an overall view of the stator component 5a. Each stage of the stator 5 is formed by combining multiple stator components 5a. Generally, a ring-shaped stator 5 is formed by combining two stator components 5a that are divided into 180-degree sections as shown in Figure 2 (only one of the two stator components is shown in Figure 2). The stator component 5a has an inner peripheral rib 51, an outer peripheral rib 53, and multiple stator blades 55.

[0024] The inner circumferential rib 51 forms the inner circumference of the stator 5. The rotor 4 is arranged in the space on the inner circumferential side of the inner circumferential rib 51. That is, the inner circumferential diameter of the inner circumferential rib 51 is larger than the diameter of the rotor 4. The outer circumferential rib 53 is arranged radially away from the inner circumferential rib 51 at a predetermined distance, forming the outer circumference of the stator 5.

[0025] The stator blades 55 are configured to connect the inner circumferential ribs 51 and the outer circumferential ribs 53. The stator blades 55 extend radially about the shaft 21. The stator blades 55 are inclined in the opposite direction to the inclination of the rotor blades 22. For example, when the rotor blades 22 are inclined from the intake side to the exhaust side, the stator blades 55 are inclined from the exhaust side to the intake side. On the other hand, when the rotor blades 22 are inclined from the exhaust side to the intake side, the stator blades 55 are inclined from the intake side to the exhaust side. The inclination directions of the rotor blades 22 and the stator blades 55 can be appropriately determined according to the rotation direction of the rotor 4, etc.

[0026] In vacuum pump 1, a predetermined product is generated from the raw material flowing in from the exhaust device, and this product may accumulate inside vacuum pump 1. To suppress this, the temperature of vacuum pump 1 is adjusted using a heater 71 and / or cooling water piping. If the temperature of vacuum pump 1 fluctuates due to this temperature adjustment, the inner circumferential ribs 51 and / or stator blades 55 of stator 5 may deform in the vertical direction (approaching the direction of rotor blades 22). If this deformation becomes excessive, stator blades 55 may come into contact with rotor blades 22.

[0027] The inventors discovered that when there are temperature variations in the vacuum pump 1, the inner peripheral rib 51 and / or the stator blades 55 deform significantly in the vertical direction because the outer peripheral rib 53 is held by the spacer 31, thus preventing the outer peripheral rib 53 from deforming in the plane of the stator 5 (i.e., in the radial direction of the stator 5). Based on this insight, the inventors discovered that by providing a deformation-allowing part 57, as described below, on the outer peripheral rib 53, the outer peripheral rib 53 can be deformed in the radial direction of the stator 5, and the inner peripheral rib 51 and / or the stator blades 55 can be deformed in the radial direction according to the deformation, thereby suppressing the deformation of the inner peripheral rib 51 and / or the stator blades 55 in the vertical direction.

[0028] As shown in Figure 2, a deformation-allowing portion 57 is provided at the circumferential end of the outer peripheral rib 53 of the stator component 5a. Preferably, the deformation-allowing portion 57 is provided at both ends of the outer peripheral rib 53 of the stator component 5a in the circumferential direction. That is, the deformation-allowing portion 57 is provided within a range of a predetermined length in the circumferential direction, starting from the end of the outer peripheral rib 53 of the stator component 5a. Although not particularly limited, the predetermined length in the circumferential direction roughly corresponds to the number of 2 to 3 stator blades 55. As shown in Figures 2 and 3, the deformation-allowing portion 57 is provided with a plurality of through portions 571 penetrating the outer peripheral rib 53 in the thickness direction. Specifically, the deformation-allowing portion 57 is provided with two large circular through portions 571a, a small circular through portion 571b disposed between the two large circular through portions 571a, and a semi-circular through portion 571c provided at the end of the outer peripheral rib 53. Figure 3 is a cross-sectional view of the portion of the stator component 5a in which the deformation-allowing portion 57 is provided.

[0029] As shown in Figures 2 and 3, the through portion 571 forms a space within the plane of the outer peripheral rib 53 (i.e., within the plane including the radial direction of the stator 5). Therefore, even when the outer peripheral rib 53 is held by the spacer 31, the through portion 571 will deform within the plane of the outer peripheral rib 53 due to temperature changes, etc. Correspondingly, the inner peripheral rib 51 and / or the stator blade 55 can deform radially in the stator 5. The radial deformation of the inner peripheral rib 51 and / or the stator blade 55 suppresses deformation of the inner peripheral rib 51 and / or the stator blade 55 in the upward and downward direction (approaching the direction of the rotor blade 22).

[0030] Furthermore, by providing semi-circular through portions 571c at both ends of the outer peripheral rib 53, the semi-circular through portions 571c can deform to a greater extent. This is because the ends of the outer peripheral rib 53 of the stator component 5a become the connection portions with another stator component 5a, and there is a gap in these portions. As a result, the inner peripheral rib 51 and / or the stator blade 55 can deform to a greater extent in the radial direction, thus further suppressing the deformation of the inner peripheral rib 51 and / or the stator blade 55 in the vertical direction.

[0031] As shown in Figures 2 and 3, the thickness of the deformation-allowing portion 57 is less than the thickness of other parts of the outer peripheral rib 53. That is, as shown in Figure 2, the deformation-allowing portion 57 is formed in a strip shape with a small thickness in the circumferential direction, starting from the end of the outer peripheral rib 53 in the circumferential direction. Moreover, a plurality of through portions 571 are provided within the area formed in the strip shape with a small thickness. As a result, when the outer peripheral rib 53 is clamped by the two spacers 31, a gap is formed between the spacers 31 and the deformation-allowing portion 57. By forming a gap between the spacers 31 and the deformation-allowing portion 57, the deformation-allowing portion 57 can easily deform in the plane of the outer peripheral rib 53, and therefore the inner peripheral rib 51 and / or the stator blade 55 can also easily deform in the radial direction.

[0032] In the vacuum pump 1, at least a portion of the outer peripheral rib 53 of the stator 5 is provided with a deformation-allowing portion 57 that allows radial deformation of the inner peripheral rib 51 and / or the stator blades 55. Thus, even if the outer peripheral rib 53 is held in place by spacers and thus difficult to deform radially, the inner peripheral rib 51 and / or the stator blades 55 can easily deform radially. As a result, for example, in the event of temperature fluctuations in the vacuum pump 1, the inner peripheral rib 51 and / or the stator blades 55 can deform radially, thereby suppressing deformation of the inner peripheral rib 51 and / or the stator blades 55 towards the rotor blades 22. Therefore, for example, even in the event of temperature fluctuations in the vacuum pump 1, the stator 5 will not come into contact with the rotor blades 22, allowing the vacuum pump 1 to operate safely. In particular, by providing the deformation allowable portion 57 at both ends of the outer peripheral rib 53 of the stator component 5a in the circumferential direction, the effect of suppressing the deformation of the inner peripheral rib 51 and / or the stator blade 55 in the direction close to the rotor blade 22 becomes more significant compared to the case where it is provided at the central part of the outer peripheral rib 53 of the stator component 5a in the circumferential direction.

[0033] The above describes one embodiment of the present invention, but the present invention is not limited to the described embodiment and various modifications can be made without departing from the spirit of the invention.

[0034] In the vacuum pump 1 of the described embodiment, by providing a through portion 571 in the deformation-allowing portion 57 of the outer peripheral rib 53, the outer peripheral rib 53 can be easily deformed radially (in the plane of the stator 5). The through portion 571 can be formed by the easy machining of opening a hole in the outer peripheral rib 53. However, the structure that makes it easy to deform the outer peripheral rib 53 is not limited to the through portion 571. For example, as shown in FIG4, by providing a groove portion 573 that does not penetrate the outer peripheral rib 53 in the deformation-allowing portion 57, the outer peripheral rib 53 can also be easily deformed. The groove portion 573 can be formed without penetrating the outer peripheral rib 53, and therefore can be formed by easy machining. FIG4 is a cross-sectional view of the deformation-allowing portion 57 provided with the groove portion 573.

[0035] In addition, for example, as shown in FIG5, the outer peripheral rib 53 can be easily deformed by providing a hollow portion 575 inside the deformation-allowing portion 57. The stator 5 with the hollow portion 575 provided in the outer peripheral rib 53 can be formed, for example, using a three-dimensional printer. The hollow portion 575 is not visible from the outside of the stator 5, thus improving the appearance of the stator 5. FIG5 is a cross-sectional view of the deformation-allowing portion 57 with the hollow portion 575 provided.

[0036] The through portion 571, groove 573, and hollow portion 575 formed in the deformation-allowing portion 57 can be any shape other than circular. For example, the through portion 571, groove 573, and hollow portion 575 can be configured by alternating V-shaped components as shown in FIG. 6 with triangular-shaped components. FIG. 6 is a diagram showing an example of a through portion 571, groove 573, and hollow portion 575 other than circular.

[0037] The deformation-allowing portion 57 can be disposed at any position on the outer peripheral rib 53 as long as it is at least a part of the outer peripheral rib 53. For example, multiple deformation-allowing portions 57 can also be disposed at equal intervals along the circumference of the outer peripheral rib 53.

[0038] The through portion 571, groove portion 573 and / or hollow portion 575 of any shape can also be formed by combining the deformation-allowing portion 57.

[0039] The vacuum pump 1 in the described embodiment is a turbomolecular pump integrating a multi-stage rotor blade 22 and a multi-stage stator 5, and a grooved pump integrating a rotor cylindrical portion 23 and a threaded stator 6. However, the grooved pump can also be omitted. That is, the stator 5 having the deformation-allowing portion 57 can also be applied to a vacuum pump that only includes a turbomolecular pump.

[0040] Those skilled in the art will understand that the plurality of exemplary embodiments are specific examples of the following forms.

[0041] (First Embodiment) A vacuum pump of the first embodiment (e.g., vacuum pump 1) includes a rotor (e.g., rotor 4), multi-stage rotor blades (e.g., rotor blade 22), and a multi-stage stator (e.g., stator 5). The rotor is housed in a housing (e.g., housing 2) and is driven to rotate. The multi-stage rotor blades are disposed on the rotor. The multi-stage stator is disposed between the multi-stage rotor blades. Each stator has an inner circumferential rib (e.g., inner circumferential rib 51), an outer circumferential rib (e.g., outer circumferential rib 53), and a stator blade (e.g., stator blade 55). The stator blade connects the inner circumferential rib and the outer circumferential rib. Each stator is housed in the housing in a state where the outer circumferential ribs are held by spacers (e.g., spacers 31). At least a portion of the outer circumferential ribs of the stator is provided with a deformation-allowing portion (e.g., deformation-allowing portion 57) that allows radial deformation of the inner circumferential ribs and / or the stator blades.

[0042] In the first embodiment of the vacuum pump, at least a portion of the outer peripheral ribs of the stator is provided with a deformation-allowing portion that allows radial deformation of the inner peripheral ribs and / or stator blades. Therefore, even if the outer peripheral ribs are held in place by spacers and thus difficult to deform radially, the inner peripheral ribs and / or stator blades can easily deform radially. As a result, for example, in the event of temperature fluctuations in the vacuum pump, the inner peripheral ribs and / or stator blades can deform radially, thereby suppressing deformation of the inner peripheral ribs and / or stator blades towards the rotor blades. Thus, for example, even in the event of temperature fluctuations in the vacuum pump, the stator will not come into contact with the rotor blades, allowing the vacuum pump to operate safely.

[0043] (Second Embodiment) In the vacuum pump of the first embodiment, each stage of the stator may also include multiple stator components (e.g., stator component 5a). In this case, a deformation-allowing portion may be formed at the circumferential end of the outer peripheral rib of the stator component. The circumferential end of the outer peripheral rib of the stator component becomes a connection portion with another stator component, where a small gap exists. As a result, the inner peripheral rib and / or stator blades can deform to a greater extent in the radial direction, thus further suppressing the deformation of the inner peripheral rib and / or stator blades in the vertical direction.

[0044] (Third Configuration) In the vacuum pumps of the first or second configuration, the thickness of the deformation-allowing portion can be less than the thickness of other parts of the outer peripheral rib. In the vacuum pump of the third configuration, when the outer peripheral rib is held by the spacer, a gap is formed between the spacer and the deformation-allowing portion, thus the deformation-allowing portion is prone to deformation in the plane of the outer peripheral rib. As a result, the inner peripheral rib and / or stator blades are also prone to radial deformation.

[0045] (Fourth form) In any of the first to third forms of the vacuum pump, the deformation-allowing part may have a through part (e.g., through part 571) that extends through the outer peripheral rib. In the fourth form of the vacuum pump, the through part can be formed by the easy machining of opening a hole in the outer peripheral rib, thus the stator can be easily machined.

[0046] (Fifth form) In any of the first to fourth forms of the vacuum pump, the deformation allowance may have a hollow portion (e.g., hollow portion 575) formed inside the outer peripheral rib. In the fifth form of the vacuum pump, the hollow portion is not visible from the outside of the stator, thus improving the appearance of the stator.

[0047] (Sixth type) In any of the first to fifth types of vacuum pumps, the deformation-allowing part may have a groove (e.g., groove 573) formed on the outer peripheral rib. In the sixth type of vacuum pump, the groove can be formed by easy machining, thus the stator can be easily machined.

[0048] 1: Vacuum pump 2: Shell 3: Base 4: Rotor 5: Stator 5a: Stator components 6: Threaded stator 11: First end 12: Second end 13: Intake port 14: End of base 15: Exhaust port 21: Axis 21A: Thrust plate 21B: Target 22: Rotor blades 23: Rotor cylindrical section 31: Spacer 44A, 44E: Bearings 44B, 44C, 44D: Magnetic bearings 45: Motor 45A: Motor rotor 45B: Motor stator 51: Inner rib 53: Peripheral ribs 55: Stator blades 57: Deformation Allowable Part 71: Heater 72: Temperature sensor 571: Through section 571a: Large circular penetrating part 571b: Small circular through section 571c: Semicircular through section 573: Groove 575: Hollow Section A1: Axis direction S1: First Internal Space S2: Exhaust space

Claims

1. A vacuum pump, comprising: The rotor is housed in the housing and driven by rotation; Multi-stage rotor blades are disposed on the rotor; The stator comprises multiple stages of rotor blades, the stator having inner circumferential ribs, outer circumferential ribs, and stator blades connecting the inner circumferential ribs and the outer circumferential ribs, and is housed in the housing with the outer circumferential ribs clamped by spacers. At least a portion of the outer circumferential ribs is provided with deformation-allowing portions, which, when the outer circumferential ribs are clamped by spacers, allow radial deformation of the inner circumferential ribs and / or the stator blades caused by temperature changes of the stator, and suppress deformation in the direction of rotation axis. Each stage of the stator comprises multiple stator components, and the deformation-allowing portions are formed at the circumferential ends of the outer circumferential ribs of the stator components.

2. A vacuum pump, comprising: The rotor is housed in the housing and driven by rotation; Multi-stage rotor blades are disposed on the rotor; A multi-stage stator is disposed between multi-stage rotor blades. The stator has inner circumferential ribs, outer circumferential ribs, and stator blades connecting the inner circumferential ribs and the outer circumferential ribs. The stator is housed in the housing with the outer circumferential ribs clamped by spacers. At least a portion of the outer circumferential ribs is provided with a deformation-allowing portion. The deformation-allowing portion allows radial deformation of the inner circumferential ribs and / or the stator blades caused by temperature changes of the stator, and suppresses deformation in the direction of rotation axis, while the outer circumferential ribs are clamped by spacers. The thickness of the deformation-allowing portion is less than the thickness of other portions of the outer circumferential ribs.

3. A vacuum pump, comprising: The rotor is housed in the housing and driven by rotation; Multi-stage rotor blades are disposed on the rotor; A multi-stage stator is disposed between multi-stage rotor blades. The stator has inner circumferential ribs, outer circumferential ribs, and stator blades connecting the inner circumferential ribs and the outer circumferential ribs. The stator is housed in the housing with the outer circumferential ribs clamped by spacers. At least a portion of the outer circumferential ribs is provided with a deformation-allowing portion. The deformation-allowing portion allows radial deformation of the inner circumferential ribs and / or the stator blades caused by temperature changes of the stator, and suppresses deformation in the direction of rotation axis, while the outer circumferential ribs are clamped by spacers. The deformation-allowing portion has a through portion that penetrates the outer circumferential ribs.

4. A vacuum pump, comprising: The rotor is housed in the housing and driven by rotation; Multi-stage rotor blades are disposed on the rotor; A multi-stage stator is disposed between multi-stage rotor blades. The stator has inner circumferential ribs, outer circumferential ribs, and stator blades connecting the inner circumferential ribs and the outer circumferential ribs. The stator is housed in the housing with the outer circumferential ribs clamped by spacers. At least a portion of the outer circumferential ribs is provided with a deformation-allowing portion. The deformation-allowing portion allows radial deformation of the inner circumferential ribs and / or the stator blades caused by temperature changes of the stator, and suppresses deformation in the direction of rotation axis, while the outer circumferential ribs are clamped by spacers. The deformation-allowing portion has a hollow portion formed inside the outer circumferential ribs.

5. A vacuum pump, comprising: The rotor is housed in the housing and driven by rotation; Multi-stage rotor blades are disposed on the rotor; A multi-stage stator is disposed between multi-stage rotor blades. The stator has inner circumferential ribs, outer circumferential ribs, and stator blades connecting the inner circumferential ribs and the outer circumferential ribs. The stator is housed in the housing with the outer circumferential ribs clamped by spacers. At least a portion of the outer circumferential ribs is provided with a deformation-allowing portion. The deformation-allowing portion allows radial deformation of the inner circumferential ribs and / or the stator blades caused by temperature changes of the stator, and suppresses deformation in the direction of rotation axis, while the outer circumferential ribs are clamped by spacers. The deformation-allowing portion has a groove formed in the outer circumferential ribs.

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