Vacuum pump, method for fixing vacuum pump, outer package, auxiliary flange, and conversion flange

文档序号:1181885 发布日期:2020-09-22 浏览:8次 中文

阅读说明:本技术 真空泵、真空泵的固定方法、外装体、辅助凸缘及变换凸缘 (Vacuum pump, method for fixing vacuum pump, outer package, auxiliary flange, and conversion flange ) 是由 大立好伸 前岛靖 高阿田勉 于 2020-02-28 设计创作,主要内容包括:本发明提供能够使用设置于通常的标准件的固定部(螺栓螺纹孔)将辅助凸缘固定于装置侧的真空泵。本发明的实施方式的真空泵中,还设置有用于固定辅助凸缘(213)的变换凸缘(200),使用设置于标准件的螺栓螺纹孔将该变换凸缘(200)和装置侧凸缘(100)固定,且将该变换凸缘和辅助凸缘固定(以下将用于变换辅助凸缘(213)和装置侧凸缘(100)的紧固连结位置的零件称作变换凸缘)。这样,能够在以往不改变标准件的设计的情况下用辅助凸缘(213)将真空泵和装置固定。(The invention provides a vacuum pump capable of fixing an auxiliary flange to a device side by using a fixing part (bolt threaded hole) arranged on a common standard component. The vacuum pump according to the embodiment of the present invention is further provided with a conversion flange (200) for fixing the auxiliary flange (213), and the conversion flange (200) and the device-side flange (100) are fixed to each other using bolt and screw holes provided in a standard material (hereinafter, a part for converting the fastening position of the auxiliary flange (213) and the device-side flange (100) is referred to as a conversion flange). Thus, the vacuum pump and the device can be fixed by the auxiliary flange (213) without changing the design of the standard component.)

1. A vacuum pump comprising an outer casing, an exhaust port, a base part, a rotating part, and an auxiliary flange,

the outer body forms an air inlet, an air inlet flange for combining with the device is formed on the side of the air inlet,

the rotating part is enclosed in the outer casing and the base part and is rotatably supported,

the auxiliary flange is provided separately from the air inlet flange and has a bolt through hole for fixing,

it is characterized in that the preparation method is characterized in that,

the auxiliary flange and the device are fixed to the device with the air inlet flange interposed therebetween, whereby the vacuum pump is attached to the device, and an impact damping mechanism is provided in the vicinity of the bolt through hole.

2. Vacuum pump according to claim 1,

the impact buffering means is a buffering portion provided in the vicinity of the rotation direction of the rotating portion of the bolt through hole, and buffers an impact transmitted between the air inlet flange and the auxiliary flange by plastic deformation.

3. Vacuum pump according to claim 2,

the buffer part is a thin-walled part,

the thin wall thickness of the thin wall portion is a thickness in a circumferential direction of the auxiliary flange.

4. Vacuum pump according to claim 2,

the buffer part is composed of the following components: the auxiliary flange is formed of a member other than the auxiliary flange, and is inserted into the bolt insertion hole or into a hole or a recess formed in the auxiliary flange.

5. Vacuum pump according to any of claims 1 to 4,

the shock absorbing mechanism is provided with a buffer member for buffering the shock transmitted between the air inlet flange and the auxiliary flange in the space formed by the air inlet flange and the auxiliary flange.

6. Vacuum pump according to any of claims 1 to 5,

the contact surface of at least a part of the contact surface of the air inlet flange and the auxiliary flange, which are in contact with each other, is subjected to a treatment for increasing the friction coefficient.

7. Vacuum pump according to any of claims 1 to 6,

the air inlet flange and the auxiliary flange are provided with positioning pins for positioning in the radial direction or the circumferential direction of the air inlet flange and the auxiliary flange, and an impact absorbing member is provided around the positioning pins.

8. A vacuum pump according to claim 7,

the positioning pin is of a step structure.

9. A vacuum pump according to claim 7 or 8,

a sleeve for filling the gap is provided around the positioning pin.

10. Vacuum pump according to any of claims 1 to 9,

in order to ensure the sealing property between the intake port flange and the device, a gap is provided between the auxiliary flange and the device when the auxiliary flange and the device sandwich the intake port flange.

11. Vacuum pump according to any of claims 1 to 10,

bolt screw holes for fixing the auxiliary flange and the intake port flange with bolts are provided in the intake port flange.

12. Vacuum pump according to any of claims 1 to 11,

the auxiliary flange and the air inlet flange are fixed by bolts,

the bolts fixing the auxiliary flange and the device are stronger than the bolts fixing the auxiliary flange and the air inlet flange.

13. Vacuum pump according to any of claims 1 to 11,

the auxiliary flange and the air inlet flange are fixed by bolts,

the number of bolt screw holes for fixing the auxiliary flange and the intake port flange is the same as the number of bolt through holes in the case of directly fixing the intake port flange to the device without passing through the auxiliary flange, and the bolt screw holes are arranged at equal intervals.

14. Vacuum pump according to any of claims 1 to 11,

the auxiliary flange and the air inlet flange are fixed by bolts,

the auxiliary flange has a divided structure divided into a plurality of parts in the circumferential direction,

the divided position of the auxiliary flange does not overlap the position of the bolt.

15. Vacuum pump according to any of claims 1 to 14,

a conversion flange having a bolt through hole at a position corresponding to a bolt screw hole for fixing formed in the device,

the air inlet flange is held between the auxiliary flange and the conversion flange,

the conversion flange is attached to the device by being fixed to the device.

16. Vacuum pump according to claim 15,

a relational expression of A.gtoreq.B.gtoreq.C is satisfied where A represents the strength of a bolt for fastening the device to the conversion flange, B represents the strength of a bolt for fastening the conversion flange to the auxiliary flange, and C represents the strength of a bolt for fastening the auxiliary flange to the intake port flange.

17. A method for fixing a vacuum pump is characterized in that,

a vacuum pump as claimed in any of claims 1 to 16,

after the auxiliary flange and the air inlet flange are temporarily fixed,

the vacuum pump is attached to the device by fixing the auxiliary flange to the device.

18. The method of fixing a vacuum pump according to claim 17,

the bolt through holes of the auxiliary flange are bored larger than the axial diameter of the bolts used, and the amount of play is eliminated when the bolts are fastened.

19. An exterior body of a vacuum pump having an air inlet flange for coupling to a device on an air inlet side,

the air inlet flange is provided with bolt screw holes for fixing the air inlet flange to an auxiliary flange by bolts, and the auxiliary flange is provided separately from the air inlet flange and has bolt through holes for fixing.

20. An auxiliary flange of a vacuum pump having an inlet flange for coupling to the device on the inlet side,

a bolt through hole for fixing is formed separately from the air inlet flange, and the air inlet flange is clamped with the device and fixed on the device.

21. A conversion flange of a vacuum pump having an intake port flange for coupling to a device on an intake port side,

a bolt through hole formed at a position corresponding to a bolt screw hole for fixing formed in the device,

the air inlet flange is clamped by an auxiliary flange which is provided separately from the air inlet flange and is provided with a bolt through hole for fixing,

the aforementioned auxiliary flange is fixed to the main body,

the conversion flange is fixed to the device.

Technical Field

The present invention relates to a vacuum pump capable of coping with a torque generated at an abnormal time, a method of fixing the vacuum pump, an outer casing, an auxiliary flange, and a conversion flange.

Background

Molecular pumps (vacuum pumps) such as turbo molecular pumps and screw groove pumps are used for exhaust gases in semiconductor manufacturing apparatuses and vacuum vessels requiring high vacuum such as electron microscopes.

Such a vacuum pump is generally provided with a flange having a predetermined size, and is fixed to a flange (hereinafter referred to as a device-side flange) of an exhaust port of a device (hereinafter referred to as a device) requiring exhaust by bolts or the like.

The flange of the vacuum pump (hereinafter, the flange of the vacuum pump is referred to as an intake port flange) and the device-side flange are fixed to each other with an O-ring interposed therebetween, thereby maintaining high airtightness.

The vacuum pump is provided with a rotor rotatably supported and rotatable at a high speed by a motor, and a stator fixed inside a housing of the vacuum pump. Further, the motor rotates at a high speed, and the rotor and the stator interact with each other to perform an exhaust function. By this exhaust action, the gas on the device side is sucked from the suction port of the vacuum pump and exhausted from the exhaust port. This achieves a high vacuum state within the device.

Generally, a vacuum pump discharges gas in a molecular flow region (a region where the degree of vacuum is high and the frequency of collision of molecules with each other is small). In order to exert the exhaust capability in this molecular flow region, the rotor needs to rotate at a high speed of about 3 ten thousand revolutions per minute.

However, when a problem occurs during the operation of the molecular pump and the rotor collides with the stator or other members fixed in the vacuum pump, the amount of angular motion of the rotor is transmitted to the stator or other fixed members, and a large torque is instantaneously generated to rotate the entire vacuum pump in the rotational direction of the rotor. This torque also applies a large stress to the device side via the flange. If torque is transmitted to the device side, a shearing force acts on the bolt that fixes the inlet flange and the device side flange, and there is a possibility that the bolt is broken or, in some cases, the molecular pump may fall down.

In such a situation, there is a possibility that a product inside the apparatus is adversely affected and an internal gas (or a toxic gas) may leak.

Therefore, in order to alleviate such a shock caused by the torque, various proposals have been made, such as providing a buffer member for the torque in the intake port flange.

Patent document 1: japanese patent laid-open No. 2017-14945.

Fig. 15 is a diagram for explaining an outline of the turbomolecular pump disclosed in patent document 1. In this turbomolecular pump, when the intake port flange 211 and the device-side flange (exhaust port flange) 100 are fixed, they are not directly fixed, but fixed via a separate auxiliary flange 213 (hereinafter, when the intake port flange 211 and the device-side flange 100 are fastened, a member for fixing therebetween is referred to as an auxiliary flange).

That is, the fastening portion 223 is fastened and connected to the apparatus-side flange 100 by the bolt 105 in a state where the clamping portion 222 of the auxiliary flange 213 is in contact with the back surface (the surface on the opposite side from the sealing surface) of the intake port flange 211. When the fastening portion 223 is fastened to the apparatus-side flange 100 by a bolt, the intake port flange 211 is sandwiched between the clamping portion 222 and the apparatus-side flange 100. Therefore, the intake port flange 211 and the apparatus-side flange 100 are sealed by the O-ring seal 110.

According to this fixing method, since the air inlet flange 211 and the apparatus-side flange 100 are not directly fixed, even if a shock is generated by the torque, the two slide each other, and the torque transmitted to the apparatus side can be reduced to some extent.

However, when such a technique is applied to a vacuum pump, the intake port flange 211 is not directly fixed to the apparatus-side flange 100 but is held between the holding portion 222 of the auxiliary flange 213 and the apparatus-side flange 100, and therefore the turbo-molecular pump (vacuum pump) is rotated greatly by an impact generated by torque. In this case, a force acts on the exhaust pipe and the electric cable connected to the vacuum pump, and the pipe and the cable that move may damage the apparatus.

In addition, when the technique of fastening the inlet flange 211 and the device-side flange 100 via the auxiliary flange 213 is applied to a vacuum pump, the auxiliary flange 213 cannot be fixed to the device-side outlet flange (device-side flange 100) with the bolt screw holes provided in a normal standard member, and therefore, a dedicated bolt screw hole must be newly provided in the device-side outlet flange. That is, in order to fasten the air inlet flange 211 and the apparatus-side flange via the auxiliary flange 213, bolt screw holes must be separately provided outside bolt screw holes provided in the standard. Therefore, it is necessary to change the design of the device-side flange or to make the size larger.

Disclosure of Invention

Accordingly, an object of the present invention is to provide a vacuum pump that can prevent the vacuum pump from rotating significantly due to a shock caused by a torque when an intake port flange is fixed to an apparatus-side flange via an auxiliary flange, and can reduce the torque applied to the apparatus.

Further, an object of the present invention is to provide a vacuum pump capable of fixing an auxiliary flange to an apparatus side using a fixing portion (bolt and screw hole) provided in a general standard.

The present invention according to claim 1 provides a vacuum pump including an exterior body having an air inlet and an air inlet flange formed on the side of the air inlet for coupling with a device, an exhaust port, a base portion, a rotating portion rotatably supported by enclosing the exterior body and the base portion, and an auxiliary flange provided separately from the air inlet flange and having a bolt through hole for fixing, wherein the auxiliary flange and the device are fixed to the device with the air inlet flange interposed therebetween, whereby the vacuum pump is attached to the device, and an impact absorbing mechanism is provided in the vicinity of the bolt through hole.

The present invention as set forth in claim 2 provides the vacuum pump as set forth in claim 1, wherein the impact damping mechanism is a damping portion which is provided in the vicinity of the rotation direction of the rotating portion of the bolt insertion hole and damps an impact transmitted between the air inlet flange and the auxiliary flange by plastic deformation.

The present invention as set forth in claim 3 provides the vacuum pump set forth in claim 2, wherein the buffer portion is a thin portion, and a thickness of the thin portion is a thickness of the auxiliary flange in a circumferential direction.

The present invention according to claim 4 provides the vacuum pump according to claim 2, wherein the buffer portion is formed of a member other than the auxiliary flange and inserted into the bolt insertion hole or a recess formed in the auxiliary flange.

The present invention as set forth in claim 5 provides the vacuum pump as set forth in any one of claims 1 to 4, wherein the shock absorbing mechanism is provided with a buffer member for buffering shock transmitted between the intake port flange and the auxiliary flange in a space formed by the intake port flange and the auxiliary flange.

The present invention according to claim 6 provides the vacuum pump according to any one of claims 1 to 5, wherein a friction coefficient is increased on at least a part of a contact surface of the suction port flange and the auxiliary flange that are in contact with each other.

The present invention according to claim 7 provides the vacuum pump according to any one of claims 1 to 6, wherein a positioning pin for positioning the air inlet flange and the auxiliary flange in a radial direction or a circumferential direction is provided on the air inlet flange and the auxiliary flange, and a member for shock absorption is provided around the positioning pin.

The present invention according to claim 8 provides the vacuum pump according to claim 7, wherein the positioning pin has a stepped structure.

The present invention according to claim 9 provides the vacuum pump according to claim 7 or 8, wherein a sleeve for filling the gap is provided around the positioning pin.

The present invention as set forth in claim 10 provides the vacuum pump as set forth in any one of claims 1 to 9, wherein, in order to ensure the sealing property between the intake port flange and the device, a gap is provided between the auxiliary flange and the device when the auxiliary flange sandwiches the intake port flange with the device.

The present invention as set forth in claim 11 provides the vacuum pump as set forth in any one of claims 1 to 10, wherein bolt screw holes for fixing the auxiliary flange and the intake port flange by bolts are provided in the intake port flange.

The present invention as set forth in claim 12 provides the vacuum pump as set forth in any one of claims 1 to 11, wherein the auxiliary flange and the intake port flange are fixed by bolts, and the bolts fixing the auxiliary flange and the device have a strength higher than that of the bolts fixing the auxiliary flange and the intake port flange.

The present invention according to claim 13 provides the vacuum pump according to any one of claims 1 to 11, wherein the auxiliary flange and the intake port flange are fixed by bolts, and bolt screw holes for fixing the auxiliary flange and the intake port flange are arranged at equal intervals in the same number as the number of bolt through holes in a case where the intake port flange is directly fixed to the device without passing through the auxiliary flange.

The present invention according to claim 14 provides the vacuum pump according to any one of claims 1 to 11, wherein the auxiliary flange and the intake port flange are fixed by bolts, the auxiliary flange has a split structure in which the auxiliary flange is split into a plurality of pieces in a circumferential direction, and the split position of the auxiliary flange does not overlap with the position of the bolts.

The present invention according to claim 15 provides the vacuum pump according to any one of claims 1 to 14, including a conversion flange having bolt insertion holes at positions corresponding to bolt screw holes formed in the device for fixing, wherein the suction port flange is held between the auxiliary flange and the conversion flange, and the conversion flange is fixed to the device to mount the vacuum pump to the device.

The present invention as set forth in claim 16 provides the vacuum pump as set forth in claim 15, wherein a relational expression of a.gtoreq.b.gtoreq.c is satisfied when the strength of the bolt fastening the device and the conversion flange is a, the strength of the bolt fastening the conversion flange and the auxiliary flange is B, and the strength of the bolt fastening the auxiliary flange and the intake port flange is C.

The present invention as set forth in claim 17 provides a method of fixing a vacuum pump, wherein the vacuum pump is attached to the apparatus by temporarily fixing the auxiliary flange and the intake port flange and then fixing the auxiliary flange to the apparatus in the vacuum pump as set forth in any one of claims 1 to 16.

The present invention as set forth in claim 18 provides the method of fixing a vacuum pump as set forth in claim 17, wherein the bolt through holes of the auxiliary flange are bored larger than the axial diameter of the bolts used in advance, and the amount of rattling is eliminated when the bolts are fastened.

The present invention according to claim 19 provides an exterior body of a vacuum pump including an intake port flange for coupling to a device on an intake port side, wherein a bolt screw hole for fixing the intake port flange with a bolt is provided in the intake port flange, in relation to an auxiliary flange provided separately from the intake port flange and having a bolt through hole for fixing.

The invention according to claim 20 provides an auxiliary flange of a vacuum pump including an inlet flange for coupling to a device on the inlet side, wherein the auxiliary flange is provided separately from the inlet flange, and a bolt insertion hole for fixing is formed, and the auxiliary flange is fixed to the device by sandwiching the inlet flange with the device.

The present invention according to claim 21 provides a conversion flange of a vacuum pump having an intake port flange for coupling to a device on an intake port side, wherein the conversion flange is provided separately from the intake port flange, has bolt through holes at positions corresponding to bolt screw holes formed in the device for fixing, and is fixed to the device by sandwiching the intake port flange by an auxiliary flange provided separately from the intake port flange and having bolt through holes for fixing.

Effects of the invention

According to the present invention, even when the auxiliary flange is used, it is possible to cope with a torque generated at an abnormal time.

Further, according to the present invention, the auxiliary flange can be fixed to the device side using a fixing portion (bolt and screw hole) provided in a general standard.

Further, according to the present invention, the fixing operation of the vacuum pump to the external device can be efficiently performed.

Drawings

Fig. 1 is a diagram showing a schematic configuration example of a vacuum pump according to an embodiment of the present invention.

FIG. 2 is a diagram for explaining embodiment 1-1.

Fig. 3 is a diagram for explaining the torque damper mechanism (a) according to embodiment 1-1.

Fig. 4 is a diagram for explaining the torque damper mechanism (b) according to embodiment 1-1.

Fig. 5 is a diagram for explaining the torque damper mechanism (c) according to embodiment 1-1.

Fig. 6 is a diagram for explaining a torque damper mechanism (d) according to embodiment 1-1.

Fig. 7 is a diagram for explaining a torque damper mechanism (e) according to embodiment 1-1.

Fig. 8 is a diagram for explaining embodiment 1-2.

Fig. 9 is a diagram for explaining an embodiment in which a sleeve is provided around the positioning pin of embodiment 2-1.

Fig. 10 is a diagram for explaining embodiments 1 to 4 and embodiments 1 to 5.

Fig. 11 is a view for explaining that a conversion flange for fixing the auxiliary flange is provided.

Fig. 12 is a diagram for explaining the relationship between the bolt strengths in the case of using the conversion flange.

Fig. 13 is a diagram for explaining the relationship between the bolt strengths in the case where the conversion flange is not used.

Fig. 14 is a diagram for explaining a positional relationship of the fixing hole of the auxiliary flange.

Fig. 15 is a diagram for explaining a vacuum pump of the related art.

Detailed Description

(i) Brief description of the embodiments

In the vacuum pump according to the embodiment of the present invention, the intake port flange 211 and the apparatus-side flange 100 are fastened and connected via the auxiliary flange 213, and a fastening and connecting portion (for example, a bolt through hole and a bolt 320) for fixing the intake port flange 211 and the auxiliary flange 213 is provided, and a torque damper mechanism (damper portion) 330 is provided in the fastening and connecting portion. The torque damper mechanism (damper portion) 330 corresponds to a shock damper mechanism.

Further, a conversion flange 200 for fixing the auxiliary flange 213 is provided, the conversion flange 200 and the apparatus-side flange 100 are fixed by bolt and screw holes provided in a standard material, and the conversion flange 200 and the auxiliary flange 213 are fixed (hereinafter, a member for converting the fastening position of the auxiliary flange 213 and the apparatus-side flange 100 is referred to as a conversion flange). Here, the device-side flange does not necessarily have to have a flange shape, and a bolt screw hole may be directly formed in the device.

In this way, even when the inlet flange 211 is fixed to the apparatus-side flange via the auxiliary flange 213, the vacuum pump can be prevented from rotating significantly due to the impact of the torque generated at the time of abnormality, the torque to the apparatus side can be reduced, and the vacuum pump and the apparatus can be fixed without changing the design of the conventional standard.

(ii) Detailed description of the embodiments

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to fig. 1 to 14.

(construction of vacuum Pump 1)

Fig. 1 is a diagram showing a schematic configuration example of a vacuum pump 1 according to embodiment 1 of the present invention, and shows a cross-sectional view of the vacuum pump 1 in an axial direction.

For convenience, in the embodiments of the present invention, the radial direction of the rotor blade is referred to as "radial (diameter) direction", and the direction perpendicular to the radial direction of the rotor blade is referred to as "axial direction (or axial direction)".

A cover (outer cylinder) 2 forming an exterior body of the vacuum pump 1 is substantially cylindrical, and constitutes a casing of the vacuum pump 1 together with a base 3 provided at a lower portion (exhaust port 6 side) of the cover 2. A gas transfer mechanism, which is a structure that allows the vacuum pump 1 to perform an exhaust function, is housed inside the casing.

In the present embodiment, the gas transfer mechanism is configured by a rotor (the rotary blade 9, the rotor cylindrical portion 10, and the like) rotatably supported, and a stator portion (the fixed blade 30, the thread groove exhaust element 20, and the like) fixed to the housing.

Although not shown in the figure, a control device for controlling the operation of the vacuum pump 1 is connected to the outside of the outer casing of the vacuum pump 1 via a dedicated line.

An inlet port 4 for introducing gas into the vacuum pump 1 is formed at an end of the cover 2. An intake port flange 211 protruding toward the outer peripheral side is formed on the end surface of the cover 2 on the intake port 4 side.

Further, an exhaust port 6 for exhausting gas from the vacuum pump 1 is formed on the downstream side of the vacuum pump 1.

The rotating body includes a shaft 7 as a rotating shaft, a rotor 8 disposed on the shaft 7, a plurality of rotating blades 9 provided on the rotor 8, and a rotor cylindrical portion (skirt portion) 10 provided on the exhaust port 6 side.

Each rotary vane 9 is formed of a member extending radially perpendicularly to the axis of the shaft 7.

The rotor cylindrical portion 10 is formed of a cylindrical member having a cylindrical shape provided concentrically with the rotation axis of the rotor 8.

In the stator pole 700, although not shown in detail, a motor portion for rotating the shaft 7 at a high speed is provided at the middle portion in the axial direction of the shaft 7. Further, radial magnetic bearing devices for supporting the shaft 7 in a radial direction (radial direction) without contact are provided on the inlet port 4 side and the outlet port 6 side with respect to the motor unit. Further, an axial magnetic bearing device for supporting the shaft 7 in an axial direction (axial direction) without contact is provided at a lower end of the shaft 7.

A fixed vane 30 is formed on the inner peripheral side of the casing. The fixed blades 30 are fixed to each other at intervals by cylindrical fixed blade spacers 35.

The rotary blades 9 and the fixed blades 30 are alternately arranged to form a plurality of layers in the axial direction, but any number of rotor components and stator components may be provided as necessary to satisfy the discharge performance required for the vacuum pump 1.

In the vacuum pump 1 of the present embodiment, a screw groove exhaust element 20 (screw groove type exhaust mechanism) is disposed on the exhaust port 6 side. A thread groove (spiral groove) is formed on the surface of the thread groove exhaust element 20 facing the rotor cylindrical portion 10. Alternatively, the screw groove may be formed on the facing surface of the rotor cylindrical portion 10 facing the screw groove discharge element 20.

The screw groove exhaust element 20 faces the outer circumferential surface of the rotor cylindrical portion 10 on the side of the facing surface facing the rotor cylindrical portion 10 (i.e., the inner circumferential surface parallel to the axis of the vacuum pump 1) with a predetermined gap therebetween, and when the rotor cylindrical portion 10 rotates at a high speed, gas compressed by the vacuum pump 1 is discharged to the exhaust port 6 side while being guided by the screw groove along with the rotation of the rotor cylindrical portion 10. That is, the thread groove is a flow path for the transport gas.

In this way, the facing surface of the thread groove exhaust element 20 facing the rotor cylindrical portion 10 and the rotor cylindrical portion 10 face each other with a predetermined gap therebetween, and thus the thread groove formed on the inner circumferential surface of the thread groove exhaust element 20 on the axial side constitutes a gas transfer mechanism for transferring gas.

In order to reduce the force of the gas flowing backward toward the inlet port 4, the smaller the interval is, the more preferable the interval is.

Further, the direction of the spiral groove formed in the spiral groove gas discharge element 20 is a direction toward the gas discharge port 6 in the case where gas is fed in the spiral groove in the rotation direction of the rotor 8.

The depth of the spiral groove becomes gradually shallower as it approaches the exhaust port 6, and the gas conveyed through the spiral groove is gradually compressed as it approaches the exhaust port 6.

According to the above configuration, the vacuum pump 1 can perform vacuum exhaust processing in the apparatus in which the vacuum pump 1 is fixed (disposed).

(embodiment 1: embodiment in which a rotation prevention structure for a vacuum pump is provided)

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