JP2002122094A - Turbo-type vacuum pump - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a turbo-type vacuum pump capable of ensuring minute clearance in the axial direction between a rotary blade and a fixed blade and providing stable air exhaust performance. SOLUTION: In this turbo-type vacuum pump, constituted such that a blade air exhaust part in which rotary blades on a rotor side and fixed blades on a stator side are arranged alternately, is provided inside a casing, and the blade air exhaust part consists of a first blade air exhaust part L1 and a second blade air exhaust part L2 arranged on a downstream side of the first blade air exhaust part and having air exhaust action due to the minute clearance in the axial direction between the rotary blade and the fixed blade, the casing of the turbo-type vacuum pump is divided into at least tow parts, namely, a casing 10a for fixing the first blade air exhaust part and a casing 10b for fixing the second blade air exhaust part.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a turbo-type vacuum pump in which gas is exhausted by a high-speed rotating rotor.

[0002]

2. Description of the Related Art An example of a conventional turbo vacuum pump is shown in FIG.
Shown in Examples of the turbo vacuum pump include a turbo molecular pump and a molecular drag pump. Conventional turbo vacuum pump, the interior of the pump casing, a rotor (rotating part) by R and a stator (fixed part) S, the first blade pumping section L ₁ and second blade pumping section L ₂ is configured I have.
The stator S includes a base 14, a fixed tubular portion 16 erected on the center, is mainly composed of a fixed portion of the blade pumping section L ₁ and groove pumping section L _2. The rotor R mainly includes a main shaft 18 inserted into the fixed cylindrical portion 16 and a rotary cylindrical portion 20 attached to the main shaft 18.

That is, a drive motor 22 is provided between the main shaft 10 and the fixed cylindrical portion 16, and an upper radial magnetic bearing 24 and a lower radial magnetic bearing 26 are provided above and below the drive motor 22. An axial bearing 28 having a target disk 28a at the lower end of the main shaft 18 and upper and lower electromagnets 28b on the stator S side is arranged below the main shaft 18. With such a configuration, the rotor R rotates at a high speed under active control of five axes.

[0004] Rotor blades 3
0 are integrally provided to constitute an impeller, and the casing 10
Fixed wings 32 alternately arranged with the rotating wings 30
Are provided, and these constitute a _first blade exhaust portion L1 which performs exhaust by interaction between the rotating blade 30 rotating at a high speed and the stationary blade 32 which is stationary. Further, the first lower blade pumping section L ₁ second wings pumping section L ₂ is provided. Here, a helical unevenness is formed on at least one of the opposing surfaces of the fixed wing 38 or the rotating wing 36 as the second wing exhaust part, and a wing exhaust part that exhausts gas in a zigzag radial direction is used. Make up.

[0005]

In a conventional turbo-type vacuum pump, the fixed blades of the second blade exhaust portion and the first blade exhaust portion are stacked in the axial direction and fastened in the axial direction by a casing. However, in particular, the second blade exhaust portion has a radial exhaust function due to the minute axial clearance between the rotor and the fixed blade. Therefore, if the minute clearance in the axial direction between the rotating blade and the fixed blade is not ensured, the exhaust performance of the vacuum pump is impaired. In addition, if the rotating blade and the fixed blade come into contact with each other, the turbo vacuum pump will be damaged.

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned circumstances, and in a blade exhaust portion having a radial exhaust function, a minute axial clearance between a rotary blade and a fixed blade is easily ensured. An object of the present invention is to provide a turbo vacuum pump capable of exhibiting performance.

[0007]

According to a first aspect of the present invention, there is provided a blade exhaust unit in which a rotor blade on a rotor side and a fixed blade on a stator side are alternately arranged in a casing. Is composed of a first blade exhaust portion and a second blade exhaust portion which is disposed downstream of the first blade exhaust portion and has an exhaust action by a minute axial clearance between the rotor and the fixed blade. In the turbo-type vacuum pump, the casing of the turbo-type vacuum pump is at least divided into a casing for fixing the first blade exhaust portion and a casing for fixing the second blade exhaust portion. It is a turbo vacuum pump characterized by the following.

According to the present invention described above, the casing is divided at each blade exhaust portion, so that the degree of axial fastening of each blade exhaust portion can be independently adjusted. That is, conventionally, the stationary blades of the radial exhaust portion and the stationary blades of the axial exhaust portion are fastened to one casing in the axial direction. In addition, since the fixed blade shape of each blade exhaust portion is different, the axial compression force or the amount of axial elastic deformation acting on each blade exhaust portion fixed blade portion is different, so that it is difficult to accurately manage these. there were. However, as described above, the casing is divided at each blade exhaust part, and the axial fastening force acting on the fixed blade part of each blade exhaust part can be easily adjusted by making the axial fastening of each blade exhaust part independent. can do. Therefore, the amount of elastic deformation of each stage of each blade exhaust portion can be accurately grasped, and accurate adjustment of the axial clearance of each stage can be performed. In particular, this effect is higher pressure,
This is effective for the second blade exhaust portion having a narrow axial clearance.

According to a second aspect of the present invention, the second blade exhaust portion has a structure in which spiral irregularities are formed on at least one of the opposed surfaces of the fixed blade or the rotating blade. The turbo type vacuum pump according to claim 1.

According to a third aspect of the present invention, there is provided the turbo vacuum pump according to the first or second aspect, wherein the first blade exhaust portion is constituted by a turbine blade.

According to a fourth aspect of the present invention, the first blade exhaust portion is a cylindrical thread groove rotor having a thread groove on at least one of the rotor side and the stator side. The turbo-type vacuum pump described in 1.

According to a fifth aspect of the present invention, the fixed wings are stacked and fixed by adjusting the clearance with respect to the rotating wings having a radial exhaust action by the minute axial clearance fixed below the rotor. The lower casing is fixed to the fixed wings, and then the fixed wings are stacked and fixed to the rotating wing fixed to the upper side of the rotor, the upper casing is fixed to the fixed wings, and the lower casing and A method of manufacturing a turbo vacuum pump, comprising joining an upper casing.

[0013] Thus, the second blade exhaust portion having the radial exhaust function by the minute axial clearance can be fastened and fixed independently of the first blade exhaust portion by adjusting the clearance. Therefore, it is possible to easily adjust the clearance of the second blade exhaust portion, and obtain good exhaust performance and operational stability after forming the pump as a whole.

[0014]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 shows a turbo vacuum pump according to a first embodiment of the present invention. In this turbo vacuum pump, the casing is divided into an upper casing 10a and a lower casing 10b. A first blade exhaust unit having turbine blades is fastened to the upper casing 10a. A second blade exhaust portion having an exhaust action by a minute axial clearance between the rotary blade and the fixed blade is fastened to the lower casing 10b. In this embodiment, the blade exhaust portion having an exhaust function by the minute axial clearance has a configuration in which spiral irregularities are formed on at least one of the opposed surfaces of the fixed blade or the rotating blade as described later. . However, in addition to the blade exhaust portion having the spiral concavo-convex portion of this embodiment, various types of pumps that radially exhaust using the axial minute clearance between the rotating blade and the fixed blade are similarly used. Applicable.

This turbo type vacuum pump has a casing 1
0a, 10b are internally rotor (rotating part) R and a stator (fixed part) S is accommodated in the axial blade exhaust portion L ₁ and the radial direction blade pumping section L ₂ consisting of the turbine blade unit between them is constituted ing. The stator S includes a base 14, a fixed tubular portion 16 erected on the center, is mainly composed of an axial blade exhaust portion L ₁ and the radial direction blade fixing portion of the exhaust portion L _2. The rotor R includes a main shaft 18 inserted into the fixed cylindrical portion 16 and a rotor main body 2 attached thereto.
0.

A drive motor 22 is provided between the main shaft 18 and the fixed cylindrical portion 16, and an upper radial bearing 24 and a lower radial bearing 26 are provided above and below the drive motor 22. And spindle 1
8, a target disk 2 at the lower end of the spindle 18 is provided.
An axial bearing 28 having upper and lower electromagnets 28b on the stator S side is provided, and touch-down bearings 29a and 29b are provided at two upper and lower portions of the fixed cylindrical portion 16. With such a configuration, the rotor R is 5
It rotates at high speed while receiving active control of the shaft.

A rotor 30 composed of turbine blades is integrally formed on the outer periphery of the upper part of the rotor body 20 of the axial blade exhaust part L ₁ , and a fixed blade 3 is formed on an inner surface of the casing 10.
2 are provided alternately with the rotor 30. Each fixed wing 32 is fixed by being pressed from above and below at its edge by a fixed wing spacer 34. As shown in FIG.
As shown in the figure, inclined blades extending in the radial direction are radially provided between the hub at the inner peripheral portion and the frame at the outer peripheral portion, and this high speed rotation gives gas molecules kinetic energy in the axial direction to exhaust gas. It is supposed to do it.

The radial blade pumping section _{L 2,} the axial blade exhaust portion L
_1, a disk-like rotating blade 36 is integrally formed on the outer periphery of the rotor body 20 in substantially the same manner as the axial blade exhaust portion L _1, and is fixed to the inner surface of the casing 10. The wings 38 are provided alternately with the rotating wings 36. Each fixed wing 38 is fixed by being pressed from above and below by a fixed wing spacer 40 at its edge.

Each of the fixed blades 38 is formed in the shape of a hollow disk, and has a spiral shape (spiral shape) on the front and back surfaces between the central hole 42 and the peripheral edge portion 44 as shown in FIG. Ridges 46 are provided, and a spiral groove 48 extending outward is formed between the ridges 46. Each fixed wing 38
3, that is, the spiral ridge 46 on the upper surface is the same as that in FIG.
2A, the gas molecules are formed so as to flow inward as shown by a solid arrow B with the rotation of the rotor 36 shown by the arrow A. On the other hand, the back surface of each fixed blade 38 is formed. That is, the spiral ridge 46 on the lower surface is formed such that the gas molecules flow outward as shown by the dashed arrow C with the rotation of the rotary blade 36 shown by the arrow A.

[0021] Thus, in the radial direction blade pumping section L _2, the rotation and the fixed blades 38 between the axially short span wings 36
A long exhaust path is formed in a zigzag manner from top to bottom, and has high exhaust / compression performance without increasing the axial length.

FIG. 4 shows a turbo vacuum pump according to a second embodiment of the present invention. The turbo vacuum pump, in front, the groove pumping section L ₃ having a tubular thread groove portion 54 having a thread groove 54a is provided, which is provided with the above-described embodiment the same radial blade pumping section L ₂ in a subsequent stage It is. In this embodiment, as compared to the combination turbo vacuum pump of the axial blade exhaust portion L ₁ and the radial blade pumping section L ₂ shown in FIG. 1, the following effects. That is, the axial exhaust portion using the turbine blade exhibits more performance in the molecular flow region, whereas the axial screw groove exhaust portion has about 1 to 1000 P
Since it works effectively in the pressure region a, it is possible to operate in a viscous flow region closer to the atmosphere.

Next, a method of manufacturing the turbo vacuum pump of the above embodiment will be briefly described. The fixed blade 38 constituting the second blade exhaust portion is usually formed as a half body or divided into three or more, and assembled and fastened via the fixed blade spacer 40 so as to be alternate with the rotor 36. .
At this time, the fixed wing is fixed to a half of the temporary casing, and fine clearance can be adjusted. After sufficient adjustment by fastening the clearance, the lower casing 1
The fixed wing assembly is inserted into and fastened to the fixed wing 0b. Then, the fixed wings and spacers, which are similarly divided into half, are assembled and fastened to the rotating wings 30 above the rotor. Since the blade exhaust at the upper part of the rotor is an exhaust in the axial direction, the accuracy of the clearance is not required as compared with the lower part. Then, the upper casing 10a is fixed to the fixed wing assembly. Further, the upper casing and the lower casing are joined by using bolt fastening or the like.

[0024] an upper casing that houses this way the upper casing axial blade exhaust portion L _1, the radial blade pumping section L ₂
Assemble independently with the lower casing containing
In particular, in the lower casing, it is possible to sufficiently increase the precision of the minute clearance between the fixed wing and the rotary wing and to perform the fastening. Since the turbo type vacuum pump exhausts gas by rotating the rotor at a high speed, the temperature may be considerably high particularly on the exhaust side. Also, when fastening fixed wings to the casing,
The fixed wing is elastically deformed in the axial direction in response to a compressive stress. Under such circumstances, by dividing the casing into two and fastening the fixed wings separately, these can be easily managed, and a turbo-type vacuum pump having high exhaust performance can be easily manufactured. In the above embodiment, an example in which the casing is divided into two parts has been described. However, the casing may be divided into three or more parts.

[0025]

As described above, according to the present invention,
In particular, it is possible to accurately adjust and fasten the axial minute clearance of the radial blade exhaust section, improving exhaust performance,
Operational stability can be obtained.

[Brief description of the drawings]

FIG. 1 is a sectional view of a turbo vacuum pump according to a first embodiment of the present invention.

2A is a plan view and FIG. 2B is a cross-sectional view illustrating a structure of a rotor constituting a first blade exhaust unit in FIG.

3A is a plan view and FIG. 3B is a cross-sectional view showing a structure of a fixed blade constituting a second blade exhaust unit in FIG.

FIG. 4 is a sectional view of a turbo vacuum pump according to a second embodiment of the present invention.

FIG. 5 is a sectional view of a conventional turbo vacuum pump.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 10 Casing 18 Main shaft 20 Rotor main body 30 Rotating wing 32 Fixed wing 34 Fixed wing spacer 36 Rotating wing 38 Fixed wing 40 Fixed wing spacer 46 Helical ridge 48 Helical groove 54 Thread groove L ₁ , L ₃ Axial wing exhaust part L _2- radial blade exhaust

Claims (5)

[Claims] 1. A wing exhaust section in which rotor-side rotors and stator-side fixed wings are alternately arranged inside a casing, wherein the wing exhaust section includes a first wing exhaust section and the first wing exhaust section. A turbo-type vacuum pump, which is arranged downstream of the blade exhaust portion and has a second blade exhaust portion having an exhaust action by an axial minute clearance between the rotating blade and the fixed blade,
A turbo-type vacuum pump, wherein a casing of the turbo-type vacuum pump is at least divided into a casing for fixing the first blade exhaust part and a casing for fixing the second blade exhaust part. 2. The turbo-type turbocharger according to claim 1, wherein the second blade exhaust portion has a helical unevenness formed on at least one of surfaces of the fixed blade and the rotating blade facing each other. Vacuum pump. 3. The turbo-type vacuum pump according to claim 1, wherein the first blade exhaust portion is configured by a turbine blade. 4. The turbo-type vacuum pump according to claim 1, wherein the first blade exhaust portion is a cylindrical screw groove rotor having a screw groove on at least one of a rotor side and a stator side. . 5. A fixed wing is fixed to a rotating wing fixed to a lower side of the rotor, which has a radially evacuating action by a minute clearance in an axial direction by adjusting a clearance, and is fixed to a lower side with respect to the fixed wing. Fixing the casing, and then stacking and fixing the fixed wings to the rotor fixed to the upper side of the rotor, fixing the upper casing to the fixed wings, and joining the lower casing and the upper casing. A method for producing a turbo vacuum pump.