JPS6185599A - Turbo-molecular pump - Google Patents

Abstract

PURPOSE:To improve the gas compression efficiency of a turbo-molecular pump by forming a projection on either of mutually-facing stator and rotor and an indent on the other and fixing them together. CONSTITUTION:At the tip 17 of the rotor blade 15 of a turbo-molecular pump, projecting parts 28, 29 and an indenting part 30 are formed, while on the inner surface 10 of the stator facing it a projecting part 31 and indenting part 32 and 33 are formed. Even if the space between the tip of the rotor blade and the inner side of the stator is so large as not to block the revolution of the rotor, gas molecules advancing toward a clearance 18 collide with projections of either the stator or the rotor and rebound from them. Thus, reverse moves of gas molecules are prevented, and the compression efficiency of the pump can be improved.

Description

[Detailed description of the invention] (Industrial application field) This invention relates to a turbomolecular pump.

(Prior art) Turbo molecular pumps are JIS Zg/27-/9g/
It was explained in ``Vacuum Pump'' by Hiroshi Ishii (Vacuum Technology Course Vol. 2, first published on January 25, 1920, published by Nikkan Kogyo Shimbun) and by John F., O'Haron, Tamotsu Noda et al. [Vacuum As disclosed in the Technical Manual (first edition dated July 3, 1939, published by Sangyo Tosho Co., Ltd.), it is a molecular pump consisting of a rotor and a stator with turbine-shaped blades, and is a molecular pump that pumps gas in the molecular flow region. This is a momentum transfer vacuum pump that is particularly effective for transportation.

The general structure of one example will be explained with reference to FIG. Bird) housed to have A. In the pump space /da having an annular cross section between the inner surface lO of the stator l/ and the outer surface 12 of the rotor 13, many rotor blades /S protrude radially outward from the rotor outer surface /2, and the stator inner surface IO A number of stator blades 16 protrude radially inward from 6. In particular, as shown partially enlarged in FIG.
The tips 19 of the stator blades/6 face the stator inner surface lθ with a relatively narrow gap /g, and the tips 19 of the stator blades/6 also have a narrow gap lθ.
! I;j2θ and faces the rotor outer surface 12. The rotor blades 15 are arranged in several stages (
In the example shown in FIG. 27, the rotor blades 15 are arranged in two stages), and each stage of the rotor blades is composed of a number of rotor blades 15 successively spaced apart from each other at equal intervals in the circumferential direction. The stator blades 16 are
@1 Tadasu! Several stages (72 in the example shown in Fig.
Each stage of stator vanes also consists of a number of stator vanes/4 successively spaced apart at equal intervals in the circumferential direction. The stator l/ has an intake port J/ that communicates with the upper part of the pump space/Hiro, and an exhaust port J/ that communicates with the lower part of the pump space/Hiro.
．． 2 = and are installed. The rotor 13 is connected to the motor taco 3 and rotates at high speed around the axis m=A by the drive of the motor 23.

In Fig. 23, the rotor blade/S in the bo/p space lhiro is shown.
and a portion of the arrangement of stator vanes 16 is shown in an exploded view. In FIG. 23, arrow B indicates the gas transport direction from the intake port 21 to the exhaust port 2-, and arrow C indicates the direction of gas transport from the intake port 21 to the exhaust port 2-.
3 indicates the direction in which the rotor blades 15 move when rotating. This figure shows two of several rotor vane stages, two of several stator vane stages, and five of each of the many vanes in each vane stage. is illustrated. Each blade is, ib is oriented Oi+ with respect to the gas transport direction B and the rotor blade traveling direction C. Specifically, the rotor blade 15 has an edge 2t opposite to the gas transport direction B, that is, an edge 2t on the intake 0.2/ side, which is located in the rotor blade traveling direction C, and has a green edge 2t in the gas transport direction B, that is, an exhaust port. The stator blade/6 is oriented so as to be ahead of the edge S on this side, and the stator blade/6 is oriented in the gas transport direction BO1ft, that is, the edge 2B on the side of the exhaust 0.22 is oriented in the rotor blade traveling direction C. It is oriented so as to precede the edge 27 in the opposite direction to the gas transport direction B, that is, the edge 27 on the side of the intake port 21 .

According to this arrangement of the blades 15t/A, when the rotor 13 is rotated, for example, from 20,00θ to 60,0θ0 per minute, the blades collide with the surfaces of the rotor blades 15 and the stator blades/6, especially in the molecular flow region. When the gas molecules collide, they receive momentum mainly from the intake 0.2/ side to the exhaust port side, and as a result, the gas is compressed in the direction shown as B as a whole. It is transported while

As a result, the side of the intake air 0.2/ is maintained at a lower pressure, that is, a higher vacuum than the side of the exhaust port 2.2.

Although the above-described turbomolecular pump has the effect of compressing and transporting gas in the B direction through the joint action of the rotor blades 15 and stator blades 16, in the conventional pump, the gap that is not affected by the joint action of these blades is At ig and co0, the pressure on the side of the exhaust port = C is higher than that on the side of the intake port = l, so the gas is discharged from the exhaust port = 0.2 as shown by arrows and E in Figure 2.2. from the side to the side of the intake port U/, that is, in the opposite direction to the B direction. Such backflow of gas in the gaps ig and 20, E)j, even if these gaps are narrow, significantly impedes the gas compression action in the B direction in the turbomolecular pump. For example, if the rotor diameter is 0.7 m and the blades are in the ig stage (
According to a Monte Carlo simulation of a turbomolecular pump with 9 stages of rotor blades and 1 stage of stator platelets, the compression ratio when the gap ig and 20 are 0.73wx in the case of hydrogen molecules is as follows. The compression ratio obtained for an ideal turbomolecular pump with zero gap is only about 60 degrees.

(Problems to be Solved by the Invention) Therefore, the present invention attempts to achieve this by means of a turbo-molecular pump in the gaps between the tips of the rotor blades and the inner surface of the stator and/or between the tips of the stator blades and the outer surface of the rotor. 8 of the gas in the opposite direction to the gas transport direction
It is an object of the present invention to eliminate the disadvantage of conventional turbomolecular pumps in that the gas compression action of the turbomolecular pump is inhibited due to the generation of motion.

(Means for solving the problem) In order to solve this problem, the turbo-molecular pump according to the present invention, when projected onto a plane tracing the rotational q-line of the rotor,
Any rotor blade 47. ! The tip of all rotor blades to a stage or all the stator blades belonging to any stator blade stage has a protruding part that protrudes toward the surface of the stator or rotor opposite to this tip, and , and the mJ notation is,
The tip has a protruding portion that protrudes toward the receding angle and a receding portion that recedes from the protruding portion;
It is characterized by

(Operation) According to the above-described configuration of the turbomolecular pump according to the present invention, there is a Even if there is a gap that is large enough not to cross the rotation of the rotor, in the region of molecular flow, gas molecules that advance toward this gap from the intake port side or the exhaust port side will mainly pass through the protrusion of the tip. colliding with a part or a protruding part of said surface and being bounced off;
Therefore, in the gap, the movement of gas molecules between the intake port side and the exhaust port side can be completely prevented or significantly reduced. Therefore, according to the present invention, the drawbacks of the conventional turbo molecular pump as described above can be solved or gf,
It can be reduced.

(Example) The turbo-molecular pump according to the present invention is shown in FIG. 1 to FIG. It has the general M construction as shown and described above with reference to these figures.

As shown in FIG. 1 corresponding to the Ryoko diagram, and FIGS. 2 and 3 showing enlarged views of the rotor 1,
30 In projection onto a plane passing through the rotational axis A (illustrated in Figure 121), the tip l of the rotor blade 15 has two protruding parts 2g and 29 and a receding part 3o of the curve of these protruding parts. The stator inner surface IO, which faces the tip 17 with a gap 1g in between, has a protruding portion 3/, and portions 3 and 33 at the rear 5 on both sides of the protruding portion 3/. The protrusions 1 and 2 g and the tassels protrude in a square shape from the retreating portion 30 toward the stator inner surface 10, and the retreating portion 30 has both the protrusions tacho g,=
Retreat to square from 7. Protruding portion 3 of stator inner surface lθ
Both the retracted portions,
32...? 3 protruding into a rectangular shape, thus both receding portions,
7.2,. 7.7 is retracted from the protruding part 31. Thus, a curved gap ig is formed between the tip 17 and the stator inner surface IO, and this gap ig is shown as F in FIG.
The widths shown by , G, and H are large, for example, 0.73 rt so that there is no risk of contact between the tip end and the stator inner surface IO when the rotor 13 rotates.
rm is determined. Furthermore, the protruding portion 2g of the tip 17.

The protruding portion 31 of the stator inner surface 10 is determined so that they overlap slightly when viewed in the direction X of the rotation 4A, as shown by J in the diagram.

According to the formation as described above, the gap igO widths F, G, H
Although is maintained at a large value that does not interfere with the high-speed rotation of the rotor 13, gas molecules advancing toward the gap ig from the intake loco side or the exhaust 0.22 side g.

, 29, J/ and is bounced back, so it cannot substantially pass through the gap ig.

In exactly the same way, in projection onto a plane passing through the rotating shaft A of the rotor/3 (shown in Figure 5.21), the stator blade 1
The tip 19 of 6 has two protruding parts 3da and 3S, and a distance between these protruding parts,
Tip l? The rotor outer surface 1, which faces each other with a gap of 0, has a protruding portion 3 and recessed portions 3g and 39 on the p1 side thereof. The protruding parts 3da and 35 protrude the rotor from the retreating part 36 toward the surface 12 in a square shape,
The recessed portion 36 recedes in a square shape from both protruding portions 3'l, 3B. The protruding portion 37 of the rotor outer surface 12 extends from both retreating portions 3g toward the retreating portion 36 of the tip iq, and from J9 to the
Therefore, both ridge-recessed portions 3g and 3q recede from the protruding portion 37. The conditions regarding the width of the bent gap -0 thus formed are the same as in the case of gap 17/za, and the state in which the protruding portions 3da, 3S, and 3 are aligned is as follows. , 3/ as described above.

According to this configuration, gas molecules cannot substantially pass through the gap 20, just as described above with respect to the gap ig.

The rotor blade tip 17 in the gap ig as described above
and the opposing stator inner surface io, the gap, and the stator blade tip l? at 20? The configuration of the rotor outer surface /2 facing this can be shaped into a seed root, but
Since the configuration in the gap 1g can obviously be applied as is to the configuration in the gap 20, only the modification of the configuration in the gap Hit will be described below.

The variant illustrated in Fig.
It is exactly the same as that shown in FIG. 2, except that the protruding portion -g, the bump and the protruding portion 31 do not overlap and there is a gap L between them. In this variant, most of the gas molecules traveling towards the gap ig are located on the protruding portions λg, 29. Some gas molecules pass through the gap L, although they collide with J/ and are bounced back.

However, by reducing the value of L, the passage of gas molecules through the gap 7g can be sufficiently reduced.

In the modification of the body diagram 5, the sales pitch of the rotor blade/S is 1.
The stator inner surface IO has two protruding portions O and one recess 244t, and the stator inner surface IO looks down on the protruding portion lI that protrudes toward the retracted portion 1 minute q/.

In the variant shown in FIG. 6, the tip 11 of the rotor blade is has a chevron-shaped protrusion, and the apex area of this chevron is the protrusion 11. ? , and the region at the foot of the chevron constitutes the receding portion Hiroq. The stator inner surface io is the rotor blade 1
It retreats in a rectangular groove shape at a location opposite to the protruding color portion 3 of No. 5 to wither the retreating portion q5, and on both sides of the retreating portion 5, it protrudes toward the retreating portion 4t of the tip/ri. Projecting part lI
6 is formed.

In the modification shown in FIG. 7, the tip 17 of the rotor blade 15 has an inverted chevron-shaped retracted portion, the central area of which is the retracted portion da 7, and the areas on both sides of this are the protruding retracted portions da g. Stator inner surface i
o is a chevron-shaped protruding part, the area at the apex is the protruding part Gede, and the areas on both sides of this are the receding parts 50.

The modification shown in FIG. 5 corresponds to the modification shown in FIG. 6, which is changed to a protruding shape with a chevron and a square groove T5 curve, and a shape that is concave in a curved shape. The tip 17 of the rotor blade IS has a protruding portion sl and a retreating portion s2,
The stator inner surface 10 has a protruding portion S3 and a retreating portion Sa.
has.

FIG. 7 shows another modification in which the protruding and recessed portions of the tips of the rotor blades 15 are indicated by 55 and S6, respectively, and the protruding and retracted portions of the stator inner surface io are indicated by 57 and 5g. shown respectively.

Figures 1 to 16 schematically illustrate an example of a method for manufacturing a rotor. In this case, a cylindrical material s9 as shown in FIGS. 70 and 11 is used. #First, this cylindrical material s9 is an annular plate portion 6o to be made into a rotor blade.
is cut to the outer surface of the rotor (jff/-
(Fig. and Fig. 13). Next, fJ=ip diagram and the 15th
As shown in the figure, each annular plate portion 0 is provided with a radial cut 6/ reaching the position of the rotor outer surface /2, and a number of plate pieces 6- protrude from the rotor outer surface /2. is formed. Finally, each plate segment 6.2 is cut out from the position shown in broken lines in FIG. 76 to position 1 shown in solid lines to form each rotor blade/S.

In accordance with the present invention, when manufacturing a rotor in which undulations consisting of a protruding portion and an O-recessed portion are formed at the tips of rotor blades 15, first, undulations extending in the axial direction are added to the circumferential surface 63 of the cylindrical material 59. 64 (processed (Fig. 77 and 7)
(Figure g). In Figure 17, the first! The intended position of the rotor outer surface 12 and the zero cut 61 illustrated in the figure is indicated by dashed lines. When the machining shown in FIG. 2 to FIG. 16 is performed on the ridge, an undulation of 6 degrees remains at the tip of the rotor blade 15.

If an undulation consisting of a protruding portion and a recessed portion is to be provided on the rotor outer surface, this undulation may be achieved at any stage from FIGS. 1212 to 76.

According to the present invention, the stator provided with protruding parts and undulations on the tips of the stator blades 16 and on the inner surface io of the stator (see figure K/D) has a half-split blade assembly 6s and a half-split blade assembly 6s. It is desirable that the spacer be substantially composed of a sysspacer 66. The half-triple blade assembly 6S is the 20th
As shown in the figure, a large number of stator blades lX (only three are shown in FIG. 20) are protruded radially inward from a semicircular plate 67, and a half-split system is used. 66
is constructed in the shape of a semicircle. When assembling the stator/l, two half-split blade assemblies S are arranged so as to jointly surround the rotor outer surface 13 in an annular shape between the two rotor blades/S. Two half blades 66 are arranged on the half blade assembly 6S so as to surround the rotor blade 15 in an annular manner. Above these two half-split vane assemblies 66, another two half-shut vane assemblies 6S are arranged in the same manner as described above, and in this way, the multi-stage stator vanes/6S are arranged. A stator ll is constructed.

(Effect of the invention) According to the turbo molecular pump according to the present invention, for example, the second
Refer to the figure and FIG. 3, the tip of the rotor blade 15 is a protruding portion 2g, 2? and a retracted portion 30, and the stator inner surface io opposite thereto has a protruding portion 31, a retracted portion, 32
．． ．． 73, or the tip l of the stator blade l and the outer surface of the rotor facing towards this are h'+
Since the width of the gap ig between the tip 17 of the rotor blade 15 and the stator inner surface 10 is [)jl,
H, or the width of the fu+gap 20 between the tip/9 of the stator blade 16 and the rotor outward l-, even if it is large enough not to disturb the rotational sound of the rotor, especially in the molecular flow region, 1
Gas molecules traveling toward ↑rHyzigi or 20 collide with any of the protrusions and are bounced back, so that the movement of gas molecules through this gap is actually blocked. Therefore, according to the present invention, the movement of gas in the direction opposite to the gas transport direction in the gap is actually suppressed, and the gas pressure is reduced by 4. ! ? , a turbomolecular pump with fully improved performance is provided.

For example, in a conventional turbomolecular pump with a rotor diameter of 0.1 m, vane or Koda stages (72 stages of rotor vanes, 72 stages of stator vanes), and gaps ig and λ0 of 0.75 ram,
Compared to the pressure in the case of hydrogen molecules, which is approximately 0% in an ideal turbomolecular pump, the rotor blade/S
The tip of the stator inner surface 10, the tip of the stator blade 16, and the rotor outer surface/, 2 are prepared according to the present invention.
Configure as shown in Figures and Figure 3, and remove overlapping joints O0l.
According to Monte Carlo simulations, when exposed to hydrogen molecules, the compression ratio for an ideal turbomolecular pump is approximately ? Improved to 9%.

[Brief explanation of the drawing]

FIG. 1 is a plane passing through the rotor plane representing the rotor vanes and the opposing stator inner surface and the stator vanes and the opposing rotor outer surface of an embodiment of a turbomolecular pump constructed in accordance with the present invention; FIG. This is a projection view. FIG. 2 is a partially enlarged projection view of FIG. aIi1 showing the tips of the rotor blades and the inner surface of the stator facing thereto. FIG. 3 is a partially enlarged projection view of the zi diagram showing the tips and ends of the stator blades and the outer surface of the rotor facing thereto. Figure 9, Figure S, Figure 6, Figure 7, Figure 3
Figures 1 and 11 are projection views of Figure 1 and 11fJ respectively representing various modifications of the embodiment illustrated in Figures 1 to 3 and especially Figure 2. FIG. 70 and FIG. 1 are a plan view and a front view showing a cylindrical material for manufacturing a rotor of a turbomolecular pump. FIGS. 12 and 13 are Xn -
They are a cross-sectional view along the 11 axis and a front view. The IgtQ diagram and the parent IS diagram show the λ-th stage of rotor manufacturing, 2!
, a sectional view along the x-xy line in Figure 13, and a positive electric current; Figure 16 shows the rotor l! 81) Figures 81) and 81) are partial top and bottom views showing the first stage in manufacturing the rotor of a turbomolecular pump according to the invention. FIG. , FIG. 79 is a partial cross-sectional view of a turbomolecular pump according to the present invention. FIG. 10 is a schematic view of the half-split system stator vane assembly included in the turbomolecular pump according to the present invention. Figure 21 shows a typical turbo molecular pump! FIG. 2 is a vertical cross-sectional view schematically showing an example of jar formation. ? Figure 1 is a diagram corresponding to Figure 1 showing the configuration of a conventional turbomolecular pump. Figure 23 shows
FIG. 2 is a diagram schematically illustrating the arrangement of rotor blades and stator blades of a turbomolecular pump. In the drawings, IO is the face of the stator, l/ is the stator,
/, 2-digit rotor surface, 13 is the rotor, 15 is the rotor blade, 16 is the stator blade, 17 is the tip of the rotor blade, /de is the tip of the stator blade, 2g, 29, 110, 11.3
．． Dag, si and S are the protruding parts at the tips of the rotor blades, 30w. Da'1, 117.52 and S6 are the retracted portions of rotor blade tips 1.3/, lI4, lIwa, 33 and 5
7 is a protruding portion of the stator surface; 3.1, 33. Its. SO, Sda and Sg are the recessed portions of the stator surface, 3d and 35 are the protruding portions of the tips of the stator blades, 36 are the recessed portions of the stator blade tips, 37 are the protruding portions of the rotor surface, 3g and 3d are the protruding portions of the stator blades. A indicates the recessed portion of the rotor surface, and A indicates the rotational axis of the rotor. Mouth 1 ≧ 1 Attachment + F) 1111 Eisuke Figure 3 Figure 8 Figure 9 Ryo Figure 22

Claims (1)

[Claims] When projected onto a plane passing through the axis of rotation of the rotor, the tips of all rotor blades belonging to any rotor blade stage or all stator blades belonging to any stator blade stage are the same as those of the stator or rotor opposite this tip. The surface has a protruding portion that protrudes toward a surface, and a recessed portion that recedes from the protruding portion, and the surface has a protruding portion that protrudes toward the retracted portion of the tip, and a recessed portion that recedes from the protruding portion. A turbomolecular pump comprising: