JP2011149437A - Rotary vacuum pump, vacuum device, and pump connection structure - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a rotary vacuum pump which reduces an impact transmitted to a device subjected to evacuation. <P>SOLUTION: By the use of a special washer formed with a bush part 17a to be inserted into a bolt hole 14, a gap G is formed between a shaft of a bolt 15 and the bolt hole 14. Then, the bolt 15 is deformed at the part of the area H2 when impact torque acts on an intake port flange 13a, and the impact is absorbed by strain energy accompanying the deformation of the bolt to suppress the transmission of the impact to a flange 16 on the device side. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

The present invention relates to a rotary vacuum pump such as a turbo molecular pump or a molecular drag pump, a vacuum apparatus to which a rotary vacuum pump is attached, and a pump connection structure.

A turbo molecular pump used for high vacuum evacuation includes a plurality of stages of rotating blades and a plurality of stages of fixed blades arranged alternately. Each of the rotor blades and the stationary blades is composed of a plurality of turbine blades. The rotor blades are formed in a rotor that is driven to rotate by a motor, and the stationary blades are fixed to the base of the pump. Furthermore, in addition to the turbine blades described above, turbomolecular pumps having a drag pump stage are also known. The drag pump stage includes a cylindrical portion formed in the lower portion of the rotor and a thread groove stator disposed in proximity to the cylindrical portion.

In the turbo molecular pump, the rotor on which the turbine blade and the cylindrical portion are formed rotates at a high speed of tens of thousands of rpm, and there is a possibility that the rotor and the stator side (for example, the thread groove stator) come into contact with each other when an abnormal disturbance acts. In that case, a large impact is applied to the stator side. In addition, a large centrifugal force is constantly acting on a rotor that rotates at high speed, and if the rotor contacts the stator side, or if it is operated continuously under conditions exceeding the design assumptions, the rotor may be destroyed. is there. In such a case, there is a problem that a larger impact is applied to the stator side, and a large shearing force is applied to the bolt that fastens the pump casing to the apparatus main body.

Therefore, it is known that a bolt formed with a plurality of steps for expanding the bolt hole prevents the bolt from breaking by preventing the shearing force from concentrating on one place (for example, Patent Documents). 1).

JP 2003-148388 A

However, in order to form a plurality of stepped holes that expand, there are a plurality of processing steps, which increases the cost of processing. Furthermore, in the above conventional technology, the bolt is in contact with the side surface of the stepped hole and plastically deforms to absorb the impact force. However, since the bolt is a stepped hole, the effect of plastic deformation is obtained. There was a disadvantage that it was not sufficiently obtained.

According to the first aspect of the present invention, there is provided a pump casing having an inlet flange, a rotor provided with a rotation-side exhaust means and driven to rotate at a high speed in the pump casing, and a rotation-side exhaust means provided in the pump casing. And a fixed-side exhaust means that generates exhaust action together, and is applied to a rotary vacuum pump that fastens an intake flange to a device to be exhausted with a bolt. A through hole having a larger diameter, and a bush that is inserted between the bolt and the through hole, and that forms a gap that allows plastic deformation of the bolt on the side of the through hole on the inlet flange mating surface. when an impact force is applied, the bolt is characterized in that plastic deformation in the gap, further comprising a holding means for holding the bush in the through hole, an exhaust target device Even when bolting inlet flange is released against, in which the bush has to be fixed to the intake port flange.
According to a second aspect of the present invention, in the rotary vacuum pump according to the first aspect, the gap formed by the bush is larger in the rotor rotational direction than in the radial direction of the inlet flange. To do.
A third aspect of the present invention is the rotary vacuum pump according to the first or second aspect, wherein the bush and the washer for the bolt are integrally formed.
The invention of claim 4 is applied to a pump connection structure in which a rotary vacuum pump that exhausts gas by rotating a rotor at a high speed with respect to a stator is connected to a vacuum device via a piping member, and a connecting flange of the piping member And a bolt for fastening the connection flange of the vacuum device, a through hole formed in one of the two connection flanges and having a diameter larger than the diameter of the bolt, and inserted between the bolt and the through hole. And a bush that forms a gap allowing plastic deformation of the bolt on the flange mating surface side, and when the impact force is applied to the bolt, the bolt is plastically deformed in the gap. Holding means to hold the screw in the through-hole, and the bush is fixed to the flange in which the through-hole is formed even when the bolting of the two connection flanges is released Is obtained by way it is.
According to a fifth aspect of the present invention, in the pump connection structure according to the fourth aspect, the gap formed by the bush is larger in the rotor rotational direction than in the radial direction of the flange.
According to a sixth aspect of the present invention, in the pump connection structure according to the fourth or fifth aspect, the bush and the washer for the bolt are integrally formed.

According to the first aspect of the present invention, when the gap forming means is provided, a gap that allows deformation of the bolt is formed, and when the intake flange moves relative to the exhaust target device due to an impact, distortion caused by the deformation of the bolt. The movement of the intake flange can be suppressed by generating energy, and the impact transmitted to the exhaust target device can be reduced.
According to invention of Claims 7-9, the impact with respect to connection object members, such as a vacuum chamber and a piping member, can be reduced.

It is a figure which shows 1st Embodiment of the rotary vacuum pump by this invention, (a) is sectional drawing of a turbo-molecular pump, (b) is a top view which shows a flange part. It is the A section enlarged view of Drawing 1 (a). (A) is a top view of the special washer 17, (b) is a sectional view. It is sectional drawing explaining the effect | action of the special washer. (A) is a top view at the time of forming the slit 17c in the special washer 17, (b) is sectional drawing at the time of providing the large diameter part 171 in the bush part 17a. It is a figure which shows the special washer 27 of the modification 1, (a) shows the state mounted | worn with the bolt hole 14, (b) is a top view of the special washer 27, (c) is sectional drawing of the special washer 27. is there. It is a figure which shows the special washer 37 of the modification 2, (a) shows the state mounted | worn with the bolt hole 14, (b) is a top view of the special washer 37, (c) is sectional drawing of the special washer 37. is there. It is a figure which shows the special washer 47 of the modification 3, (a) shows the state mounted | worn with the bolt hole 14, (b) is a top view of the special washer 47, (c) is sectional drawing of the special washer 47. is there. It is a figure which shows the special washer 57 of the modification 4, (a) is a top view, (b) is BB sectional drawing, (c) is CC sectional drawing. It is a figure which shows the turbo-molecular pump 1 in which the special washer 57 is used, (a) is sectional drawing, (b) is a top view which shows a flange part. It is a figure which shows the elongate hole 145 part of FIG. 10 in detail, (a) is an enlarged view of the E section of FIG.10 (b), (b) is FF sectional drawing of Fig.11 (a). It is a figure which shows 2nd Embodiment of the rotary vacuum pump by this invention, and is sectional drawing which shows schematic structure of a molecular drag pump. It is a figure which shows the valve | bulb 101 and the piping 102 which were provided between the rotary vacuum pump and the vacuum chamber. It is a figure explaining the flame | frame 104 provided in the apparatus side. It is sectional drawing at the time of using the stepped volt | bolt 60 instead of the volt | bolt 15. FIG.

Hereinafter, the best mode for carrying out the present invention will be described with reference to the drawings.
-First embodiment-
FIG. 1 is a diagram showing a first embodiment of a rotary vacuum pump according to the present invention, and is a diagram showing a schematic configuration of a turbo molecular pump. 1A is a sectional view, and FIG. 1B is a plan view showing a flange portion. The plan view shows the upper half of the flange. The turbo molecular pump 1 shown in FIG. 1 is a magnetic bearing type pump, and the rotor 2 is supported in a non-contact manner by magnetic bearings 4 a to 4 c provided on the base 3. 4a and 4b are radial magnetic bearings, and 4c is an axial magnetic bearing.

The base 3 is provided with a motor 6 that rotationally drives the rotor 2, touchdown bearings 7a and 7b, and gap sensors 5a, 5b, and 5c for detecting the floating position of the rotor 2, respectively. Mechanical bearings are used for the touchdown bearings 7a and 7b, and the rotor 2 is supported when the magnetic levitation of the rotor 2 by the magnetic bearings 4a to 4c is turned off.

The rotor 2 is formed with a plurality of stages of rotating blades 8 in the direction of the rotation axis. Fixed wings 9 are respectively disposed between the rotating wings 8 arranged vertically. These rotor blades 8 and fixed blades 9 constitute a turbine blade stage of the turbo molecular pump 1. Each fixed wing 9 is held by a spacer 10 so as to be sandwiched up and down. The spacer 10 has a function of maintaining a gap between the fixed wings 9 at a predetermined interval as well as a function of holding the fixed wings 9.

Further, a screw stator 11 constituting a drag pump stage is provided at the rear stage (lower side in the figure) of the fixed blade 9, and the inner peripheral surface of the screw stator 11 faces the cylindrical portion 12 of the rotor 2 at a predetermined interval. The fixed wing 9 held by the rotor 2 and the spacer 10 is housed in a casing 13 in which an inlet flange 13a is formed. Eight bolt holes 14 are formed at equal intervals in the intake flange 13a, and the intake flange 13a is fixed to the apparatus-side flange 16 by eight bolts 15. The flange thickness, the bolt size used, and the number of bolts are determined by the standard depending on the diameter of the inlet flange 13a.

FIG. 2 is an enlarged view of a portion A in FIG. 1 (a), and shows the bolt hole 14 portion of the intake port flange 13a in detail. When the inlet flange 13a is fixed to the apparatus-side flange using the bolt 15, a special washer 17 as shown in FIG. 3 is attached. Reference numeral 18 denotes an ordinary spring washer. 3A is a plan view of the special washer 17, and FIG. 3B is a cross-sectional view. The special washer 17 includes a bush portion 17a and a flange portion 17b, and is formed of iron or stainless steel. A hole 170 into which the bolt 15 is inserted is formed in the bush portion 17a.

The inner diameter D of the bolt hole 14 formed in the inlet flange 13a is set larger than the standard bolt hole diameter corresponding to the dimension of the bolt 15 as will be described later. The outer dimension d of the bush portion 17a of the special washer 17 may be a tolerance dimension that can be easily inserted into the bolt hole 14, and the height dimension is H1. Therefore, as shown in FIG. 2, a gap G is formed between the bolt 15 and the bolt hole 14 at a depth of H2 from the upper surface of the intake port flange 13a.

FIG. 4 is a diagram for explaining the operation of the special washer 17, in which the bolt hole 14 portion is sectioned along the circumferential direction. In the bolt 15, the region H <b> 3 is screwed into the female screw portion of the apparatus side flange 16 from the tip of the shaft, and the area H <b> 3 is restrained by the apparatus side flange 16. On the other hand, the portion of the dimension H2 from the mating surfaces of the flanges 13a, 16 is in an unconstrained state with a gap G formed between the shaft of the bolt 15 and the inner wall of the bolt hole 14 as described above.

In the state of FIG. 4, when the impact force F is applied to the inlet flange 13a in the rotor rotation direction (left direction in the figure), the inlet flange 13a moves to the left. At this time, a portion of the bolt 15 in the region H3 is restrained by the apparatus-side flange 6, while a portion of the bolt 15 to which the bush portion 17a is attached moves to the left while being restrained by the inlet flange 13a. As a result, the portion of the region H2 in which the shaft of the bolt 15 is in an unconstrained state is deformed, and the kinetic energy due to the impact force F is absorbed as distortion energy of the bolt 15 by the deformation, and the bolt 15 is prevented from being broken.

In addition, it is better to set the height H1 of the bush part 17a small so that the distortion area | region H2 of the volt | bolt 15 may become large. Further, if the amount of deformation of the bolt 15 is increased, the amount of energy absorbed by the strain increases, so that the outer diameter d of the bush portion 17a is preferably large. Usually, according to the size of the inlet flange 13a, the size (nominal diameter) of the bolt 15, the number of bolts, the inner diameter of the bolt hole 14, and the pitch circle diameter (PCD) of the bolt hole 14 are determined by the standard. Yes. Therefore, in order to align with the apparatus-side flange 16, other than the above-described inner diameter D of the bolt hole 14 is set according to the standard.

Thus, in this embodiment, by attaching the special washer 17 having the bush 17 a to each bolt 15, a gap is formed between the bolt 15 and the bolt hole 14, and the non-restraining region H 2 is formed in the bolt 15. Can be formed. As a result, even when an impact torque is applied to the inlet flange 13a, the shearing force acting on the bolt 15 is decomposed into two directions of shearing force and pulling force due to deformation of the portion of the bolt 15 in the unrestrained region H2. Therefore, the shear energy can be received as the strain energy of the bolt 15, and the impact torque transmitted to the device side can be reduced. Further, since the bolt 15 is deformed, the shearing force due to the impact torque can be received by all the bolts 15 used for fastening, so that the bolt strength can be effectively utilized and the bolt 15 is prevented from being broken. can do.

In addition, as shown to Fig.5 (a), the vertical slit 17c may be formed in the special washer 17, and you may make it press-fit the bush part 17a to the bolt hole 14 of the inlet flange 13a. Further, as shown in FIG. 5B, a large-diameter portion 171 is provided at the base portion of the bush portion 17a in consideration of the press-fitting allowance, and the large-diameter portion 171 is press-fitted into the bolt hole 14 or shrink-fitted. You may do it.

Thus, by attaching the special washer 17 to the bolt hole 14, workability at the time of mounting the pump is improved. In addition, about the thing which attached the special washer 17 to the volt | bolt hole 14 and made it the structure which does not drop, there exist a thing like the modifications 1-3 shown below.

[Modification 1]
6A and 6B are diagrams showing a first modification of the special washer 17, wherein FIG. 6A shows a special washer 27 attached to the bolt hole 14 of the inlet flange 13a, and FIG. 6B is a plan view of the special washer 27. c) is a cross-sectional view of the special washer 27. The special washer 27 also includes a bush portion 27a and a flange portion 27b, and a bolt hole 270 is formed so as to penetrate the bush portion 27a. Further, the bush portion 27a is formed with a protrusion 271 that goes around the outer peripheral surface.

On the other hand, as shown to Fig.6 (a), the groove | channel 14a which makes one round of an internal peripheral surface is formed in the bolt hole 14 of the inlet flange 13a. When the bush portion 27 a of the special washer 27 is inserted into the bolt hole 14, the special washer 27 is attached to the bolt hole 14 by the protrusion 271 engaging with the groove 14 a. Since the protrusion 271 and the groove 14 a are engaged, the special washer 27 does not fall out of the bolt hole 14.

[Modification 2]
7A and 7B are diagrams showing a second modification of the special washer 17, wherein FIG. 7A shows the special washer 37 attached to the bolt hole 14 of the inlet flange 13a, and FIG. 7B is a plan view of the special washer 37. c) is a cross-sectional view of the special washer 37. The special washer 37 also includes a bush portion 37a and a flange portion 37b, and a bolt hole 370 is formed so as to penetrate the bush portion 37a. Further, on the outer peripheral surface of the bush portion 37a, a mountain-shaped convex portion 371 that extends in the direction of the flange portion 37b like a hose nipple is formed in three steps in the axial direction. The number of steps of the chevron convex portion 371 is not particularly limited, and may be one or two.

The outer diameter of the chevron convex portion 371 is set slightly larger than the inner diameter of the bolt hole 14 formed in the inlet flange 13a, and the bush portion 37a is mounted so as to be press-fitted into the bolt hole 14. As a result, the special washer 37 does not fall out of the bolt hole 14.

[Modification 3]
FIGS. 8A and 8B are diagrams showing a third modification of the special washer 17, wherein FIG. 8A shows a special washer 47 attached to the bolt hole 14 of the inlet flange 13a, and FIG. 8B is a plan view of the special washer 47. c) is a cross-sectional view of the special washer 47. The special washer 47 also includes a bush portion 47a and a flange portion 47b, and a bolt hole 470 is formed so as to penetrate the bush portion 47a. Further, a groove 471 is formed around the outer peripheral surface in the bush portion 47a.

As shown in FIG. 8A, a screw hole 140 penetrating from the side surface to the bolt hole 14 is formed in the intake port flange 13a. The screw hole 140 is formed to face the groove 471 of the bush portion 47a inserted into the bolt hole 14. The special washer 47 is locked to the bolt hole 14 by pressing the set screw 141 attached to the screw hole 140 against the groove 471 of the bush portion 47 a inserted into the bolt hole 14. By keeping the special washer 47 attached to the bolt hole 14, it is possible to prevent the special washer 47 from falling off or lost. The special washers 17 to 47 described above are formed by integrating the bush portions 17a to 47a and the flange portions 17b to 47b. However, the bush portions 17a to 47a and the flange portions 17b to 47b are separately provided as separate parts. It may be provided. In that case, a normal washer may be used instead of the flanges 17b to 47b.

[Modification 4]
In the special washer 17 described above, the circular flange portion 17b and the cylindrical bush portion 17a were provided. However, like the special washer 57 shown in FIG. 9, the elliptical flange portion 57b and the cross-sectional shape are oval. You may make it comprise with the columnar bush part 57b which is. Bolt holes 570 are formed in the bush portion 57a. In FIG. 9, (a) is a plan view of the special washer 57, (b) is a BB cross-sectional view, and (c) is a CC cross-sectional view.

10A and 10B are diagrams showing the turbo molecular pump 1 in which the special washer 57 is used. FIG. 10A is a cross-sectional view, and FIG. 10B is a plan view showing a flange portion. The plan view shows the upper half of the inlet flange 13a. FIG. 10 is similar to FIG. 1 except for the shape of the bolt hole formed in the inlet flange 13a.

That is, a long hole 145 is formed instead of the circular hole 14 for the bolt. The same number of the long holes 145 as the bolt holes 14 in FIG. 1 are formed, and the bolt hole pitch circle diameter (PCD) is also set equal. The horizontal cross-sectional shape of the long hole 145 is the same as the horizontal cross-sectional shape of the bush portion 57a, and the bush portion 57a of the special washer 57 is inserted into the long hole 145. The major axis direction of the long hole 145 coincides with the circumferential direction (that is, the rotor rotation direction).

11A and 11B are diagrams showing in detail the elongated hole 145 portion, in which FIG. 11A is an enlarged view of a portion E in FIG. 10B, and FIG. 11B is a cross-sectional view taken along line FF in FIG. As described above, since the major axis direction of the long hole 145 coincides with the rotor rotation direction, the gap G1 in the rotor rotation direction is set larger than the gap G shown in FIG. Yes. Therefore, when the impact force F acts on the intake flange 13a, the shaft of the bolt 15 can be greatly deformed. As a result, it is possible to more effectively absorb the impact energy due to the strain energy accompanying the deformation of the bolt 15.

As shown in FIG. 11A, since a gap is also formed in the radial direction between the bolt 15 and the elongated hole 145, when the inlet flange 13a is deformed in the radial direction, the bolt 15 is It is possible to prevent the bolt 15 from breaking in the radial direction by deforming in the radial direction.

-Second Embodiment-
In the first embodiment described above, the case where the present invention is applied to a turbo molecular pump has been described. However, in the present embodiment, a case where the present invention is applied to a molecular drag pump will be described. FIG. 12 is a cross-sectional view showing a schematic configuration of a molecular drag pump. The molecular drag pump shown in FIG. 12 is also a magnetic bearing type rotary vacuum pump, and the magnetic bearing part and the rotary drive part have the same structure as the turbo molecular pump shown in FIG. Below, it demonstrates centering on a different part from FIG.

In the molecular drag pump shown in FIG. 12, a screw groove portion 20 is formed on the outer peripheral surface of the rotor 2, and a cylindrical stator 21 is provided around the rotor 2 so as to face the screw groove portion 20. . The gap between the thread groove 20 and the stator 21 is set to 1 mm or less, and the pump action is generated by rotating the rotor 2 at high speed, and the gas is exhausted. The molecular drag pump having such a structure exerts its ability in a higher pressure region than the turbo molecular pump. Note that the thread groove 20 may be formed on the stator 21 side, and the outer periphery of the rotor 2 may be cylindrical.

The molecular drag pump also rotates at a high speed of several tens of thousands of rpm like the turbo molecular pump. When the rotor 2 and the stator 21 come into contact with each other or the rotor suddenly stops due to contact or the like, a large impact is exerted on the stator side. Will be added. In particular, unlike a molecular pump having a turbine blade, in the case of a molecular drag pump, since the screw groove is formed from the upper end to the lower end of the rotor, the rotor weight tends to be larger than a turbo molecular pump having the same diameter, The impact will increase accordingly.

Therefore, also in the present embodiment, the same fixing method as that of the first embodiment is adopted as the fixing method of the inlet flange 13a of the molecular drag pump and the flange 16 of the apparatus-side vacuum chamber. For example, a special washer 17 and a spring washer 18 are used for the bolt 15 as in the structure shown in FIG. The bolt hole 14 of the inlet flange 13a has a hole diameter for the special washer 17.

Further, when a rotary vacuum pump 103 such as a turbo molecular pump or a molecular drag pump is mounted in a vacuum chamber, it is often fixed via a valve such as a gate valve or a control valve as shown in FIG. . The valve 101 is fixed to the vacuum chamber 100 via a pipe 102. Even in such a configuration, in order to suppress the impact on the vacuum chamber 100, a fixing method similar to that of the first embodiment is adopted in each fixing portion of the valve 101 and the pipe 102. As a result, the impact energy can be more effectively absorbed by the strain energy accompanying the deformation of the bolt, and the breakage of the bolt 15 can be prevented.

In the example shown in FIG. 13, since the screw hole for the bolt 15 is formed in the valve 101, a through hole 14 is formed in the pump-side intake flange 13a and a special washer is formed on the intake flange 13a side. 17 was attached. However, in the case of a flange structure in which a bolt through hole is formed on the valve side, the special washer 17 may be mounted on either the pump side or the valve side flange. The same applies to the connection portion between the valve 101 and the pipe 102 and the connection portion between the pipe 102 and the vacuum chamber 100.

In the mounting structure of FIG. 13, the rotary vacuum pump 103 is fixed in such a manner that it is suspended from the valve 101, but the bottom surface of the base 3 of the vacuum pump 103 is fixed to the apparatus side frame 104 as shown in FIG. You may make it do. The same fixing method as that of the first embodiment described above is also used for fixing the base bottom surface and the frame 104. For example, the special washer 17, the spring washer 18 and the bolt 15 are used for fixing. Bolt holes 14 corresponding to the special washers 17 are formed in the frame 104.

Thus, when the rotary vacuum pump 103 is mounted on the apparatus, not only the suction port flange 13a of the vacuum pump 103 is fixed to the apparatus, but also the pump base portion is fixed to the apparatus, so that an emergency stop such as a pump sudden stop Energy at the time can be absorbed by plastic deformation of more bolts, and impact transmitted to the device side can be reduced. In particular, when the configuration shown in FIG. 14 is used, energy is released to the frame side, so that damage to the vacuum chamber 100, the pipe 102, and the valve 101, which are important parts of the apparatus, can be reduced. In addition, the fixing method of the present embodiment can be easily implemented at each connection point of the vacuum apparatus by attaching a gap forming means such as a bush to a bolt through hole that has been conventionally provided.

In the embodiment described above, the special washers 17 to 57 are used as means for forming a gap between the bolt 15 and the bolt hole 14, but instead of using the special washers 17 to 57, the bolt 15 is used instead. A stepped bolt 60 as shown in FIG. 15 may be used. In the stepped bolt 60, the lower neck portion having a length H <b> 1 is a large diameter portion 60 a having a dimension substantially equal to the inner diameter of the bolt hole 14. The gap G is formed by providing the large diameter portion 60a. 61 is a general flat washer.

In addition, the present invention is not limited to the above embodiment as long as the characteristics of the present invention are not impaired. For example, the magnetic bearing type rotary vacuum pump that supports the rotor 2 in a non-contact manner by a magnetic bearing has been described as an example. However, the present invention is not limited to the magnetic bearing type and can be applied to a rotary vacuum pump using a mechanical bearing.

In the correspondence between the embodiment described above and the elements of the claims, the bolt hole 14 is a through hole, the bush portions 17a to 57a are gap forming means and bushes, the flange portions 17b to 57b are washers, and the frame 104. , The rotary blade 8, the cylindrical portion 12 and the screw groove portion 20 constitute the rotary side exhaust means, and the fixed blade 9, the screw stator 11 and the stator 21 constitute the fixed side exhaust means.

DESCRIPTION OF SYMBOLS 1 Turbo molecular pump 2 Rotor 3 Base 4a-4c Magnetic bearing 6 Motor 8 Rotor blade 9 Fixed blade 11 Screw stator 12 Cylindrical part 13 Casing 13a Inlet flange 14 Bolt hole 15 Bolt 16 Apparatus side flange 17-57 Special washer 17a-57a Bush Parts 17b to 57b flange part 20 thread groove part 21 stator 60 stepped bolt 100 vacuum chamber 101 valve 102 pipe 103 rotary vacuum pump 104 frame

Claims (6)

A pump casing formed with an inlet flange, a rotor provided with a rotation-side exhaust means and driven to rotate at a high speed in the pump casing, and provided in the pump casing and cooperating with the rotation-side exhaust means. A rotary vacuum pump comprising a fixed-side exhaust means for generating an exhaust action, and fastening the intake flange to the exhaust target device with a bolt;
A through hole formed in the inlet flange and having a diameter larger than the diameter of the bolt;
A bush that is inserted between the bolt and the through hole, and that forms a gap that allows plastic deformation of the bolt on the side of the inlet flange mating surface of the through hole;
When an impact force is applied to the bolt, the bolt is plastically deformed in the gap .
Furthermore, a holding means for holding the bush in the through hole is provided,
The rotary vacuum pump characterized in that the bush is fixed to the intake flange even when the bolt fastening of the intake flange to the exhaust target device is released. The rotary vacuum pump according to claim 1,
The rotary vacuum pump characterized in that the gap formed by the bush is larger in the rotor rotational direction than in the radial gap of the inlet flange. The rotary vacuum pump according to claim 1 or 2 ,
The rotary vacuum pump characterized in that the bush and the washer for the bolt are integrally formed. In a pump connection structure in which a rotary vacuum pump that exhausts gas by rotating a rotor at a high speed with respect to a stator is connected to a vacuum device via a piping member,
A bolt for fastening the connection flange of the piping member and the connection flange of the vacuum device;
A through hole formed in one of the two connection flanges and having a diameter larger than the diameter of the bolt;
A bush that is inserted between the bolt and the through hole, and that forms a gap allowing plastic deformation of the bolt on the flange mating surface side of the through hole,
A pump connection structure characterized in that when an impact force is applied to the bolt, the bolt is plastically deformed in the gap ,
Furthermore, a holding means for holding the bush in the through hole is provided,
The pump connection structure, wherein the bush is fixed to the flange in which the through hole is formed even when the bolt fastening of the two connection flanges is released. In the pump connection structure according to claim 4 ,
The pump connection structure characterized in that the gap formed by the bush is larger in the rotor rotational direction than in the radial gap of the inlet flange. The pump connection structure according to claim 4 or 5 ,
A pump connection structure characterized in that the bush and the washer for the bolt are integrally formed.

Images