JPH01219393A - Molecular vacuum pump - Google Patents

Abstract

PURPOSE:To aim at reduction in working manhour and improvement in accuracy of finishing as well as to get rid of such an accident as cutting operator's hands by installing an axial flow type pumping element, arranged with a moving blade and a stationary blade alternately, in space between an inlet and an outlet, and forming the stationary blade with plastics. CONSTITUTION:An axial flow type pumping element 7, where plural pieces of moving blades 5 being rotated by a rotor 4 and plural pieces of stationary blades 6 being fixed to a casing 1 are set up in space between a inlet 2 and an outlet 3. Both first and second stationary blades 61, 62 constituting the stationary blades 6 are formed with plastics. Thus, working manhour for the stationary blade 6 is reducible, and that forming accuracy for the stationary blade 6 is securable. In addition, such a possibility that an operator or the like may cut his hands by its edge part can be lessened as little as negligible.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention is equipped with an axial flow pump element having rotor blades and stator vanes, and is capable of pumping from a low vacuum of approximately 1 torr to 10 torr. The present invention relates to a molecular vacuum pump that achieves a wide range of degrees of vacuum up to an ultra-high vacuum, and is suitable for use, for example, in the semiconductor manufacturing sector.

(Prior art) This type of vacuum pump has been known for a long time from Japanese Patent Publication No. 47-33446, etc., and as shown in Fig. 10, a moving blade having a plurality of blades (a) on the circumference. (A) and stator vanes (B) having a plurality of vanes (b) on the circumference are alternately stacked.
Rotate the rotor (R) that supports the intake port (L) at high speed.
Vacuuming is performed from the inside toward the exhaust port (H). By the way, the rotor blade (A) and the stationary blade (B) have a plurality of blades (a) and (b) on the circumference, and these blades (A) and (B)
These six blades (A) and (B) require high-precision machining because they are alternately stacked and the rotor blades (A) are rotated at high speed between the stationary blades (B). To obtain (A) and (B), machining by cutting is generally employed.

However, according to the machining process, the machining itself is complicated and takes a long time, and the shavings are wasted and the material yield is poor.

For this reason, as disclosed in Japanese Utility Model Application Publication No. 0-143192, as shown in FIG.
After punching the rotor blades (A) and stationary blades (B) from a blank, the blades (a) and (b) are supported by press processing to make them inclined, and the method disclosed in Japanese Patent Application Laid-Open No. 81-215492. As shown in Fig. 12, the metal plate (W) is pressed into a square shape with a pair of press dies (M) having saw blades (K), and the spaces between each blade (a) and (b) are A processing technique has been proposed in which the material is separated and tilted at the same time, with the aim of improving processability.

(Problem to be solved by the invention) However, the former improvement plan requires two steps, punching and twisting, and since metal materials are used, the edges of the blades (a) and (b), etc. There is also a risk that workers may cut their hands during lamination work. Also, in the latter improvement plan,
Processing can be done in one step, but the saw blade (K) creates a sharp cut, which does not provide any safety for the worker. Furthermore,
In both cases, a single metal plate (W) is deformed to form a blade (a) (
b) is inclined, there is a risk that the angle of inclination may be distorted due to residual stress of the material, etc.

Furthermore, corrosive gases such as fluorine-based and chlorine-based gases are frequently used in the semiconductor manufacturing sector where this type of vacuum pump is used.
A chamber filled with the corrosive gas may also be evacuated, but in such a case, since metal materials are easily corroded, it is generally necessary to separately apply a corrosion-resistant resin coating treatment.

Furthermore, as schematically shown in FIG. 9, in metal materials, the initial content of gas molecules contained in the metal is generally small (
However, it has a physical property that it takes a long time for the molecules to be released from the metal (compared to resin), and even if vacuuming progresses, it will not be possible to release molecules from the six wings (A) and (B). There is also a concern that the vacuum level may be impaired by molecules released over a long period of time.

Based on the above, in the present invention, we focused on molding using resin, but in this case, since the rotor blade side is rotated at high speed and it is necessary to guarantee a certain degree of rigidity, we decided to actively use resin. The matter will be postponed and left as a matter of discretion.
By making at least the stator blades resin, it is possible to reduce the number of machining steps and improve machining accuracy, and there is also less concern that workers will cut their hands at the edges (also, there is no possibility of releasing corrosive gases or molecules containing them). The purpose of the present invention is to provide a molecular vacuum pump that can also reduce the adverse effects caused by.

(Means for Solving the Problems) Therefore, the present invention provides an axial flow system in which rotor blades (5) and stationary blades (θ) are alternately arranged between the intake port (2) and the exhaust port (3). In the molecular vacuum pump provided with a shaped pump element (7), the stationary blade (6) is made of synthetic resin.

(Function) By making the stator vane (θ) resin, the stator vane (6) can be processed at once by molding, the number of processing steps can be reduced, and the disadvantage that the inclination angle of the blade becomes incorrect later can also be eliminated. Furthermore, by using the same resin, the sharpness at the edge portion of the stator vane (6) can be alleviated, and safety in lamination work, etc. can be ensured. Furthermore, corrosion due to corrosive gases can also be reduced. Moreover, the resin material is
Although the initial content of gas molecules is large, most of them are released in a short period of time, so it is possible to reduce the problem of the degree of vacuum being disturbed once the vacuum is drawn down.

(Example) In Fig. 1, (1) is a casing having a roughly cylindrical shape, and a rotor (4) is connected between an intake port (2) provided on the negative side and an exhaust port (3) provided on the other side. An axial pump element (7) is provided, in which a plurality of rotating rotor blades (5) and a plurality of stationary blades (6) fixed to the casing (1) are arranged alternately, and a motor (40 ) by rotating the rotor (4) at high speed (e.g. 3θOOOrpm), the rotor blade (5) is moved at a circumferential speed of about 200 to 400 m/s, which is close to the molecular speed, and the chamber for semiconductor wafers etc. is attached to the inlet flange (20). (21) The inside is evacuated.

The motor (40) is supported by a frame (41), and an oil pickup (43) is provided from an oil droplet (42) provided below.
The oil is pumped up to the oil supply passage (45) in the drive shaft (44) through the oil supply passageway (45), and is supplied to the upper and lower bearings (46) (47).
Separate the motor chamber <4g> with the compartment lid (49) and the air intake port (2).
The exhaust flow path (23) side from the exhaust port (3) to the exhaust port (3) is sealed with oil. In addition, the one in Fig. 1 is a rotating inner cylinder (6) that uses the skirt of the rotor (4) in combination with an axial flow pump element (7), and a stationary pump that also serves as a support for the stationary blades (6). an outer cylinder (6), and a rotating inner cylinder (6).
Although a screw-type pump element (11) having a thread groove (10) deep on the intake side and shallow on the exhaust side is used in combination with the pump element, the axial flow pump element (7) alone may be used.

As clearly shown in FIGS. 2 and 3, the rotor blade (5) includes two groups of blades with different shapes, and includes a first rotor blade (51) (a second rotor blade) on the side closer to the intake port (2). Feather (510) formed on the figure)
The length (Ll) and inclination angle (θ1) of the second
They are thicker (L2) (θ2) than those of the blades (520) formed on the rotor blades (52) (Fig. 3).Similarly, the stator blades (6) are also As shown in the figure, there are two groups, and the first stationary blade (C31
) (Fig. 4), the length (L3) and inclination angle (θ3) of the blade (610) of the second stationary blade (82) (Fig. 5) corresponding to the second moving blade (52) ( 620) that of (L4) (
θ4).

In the above configuration, the first and second stator blades (61) and (82) constituting the stator blade (6) are made of synthetic resin. For example, FRP composited with carbon fiber or the like is suitable for the resin.

In addition, each stator blade (81) Cf32) is a rotor blade (51) (52).
) are stacked and assembled on the upper support cylinder (50) of the rotor (4), and then the two-split structure (81a, 81b) (82a, 82b) can be inserted between the rotor blades. For this purpose, each stator vane (81) (62) may be integrally formed into a disk shape with resin and then cut at the center. Also, static wings (
81) When converting (62) into resin, two members are formed in advance using separate molds, and as shown in FIG.
2b) may be provided with a pair of step portions (11) and (12), a pair of retaining protrusions (13), and a retaining hole (14) thereof, so that the two members can be reliably brought into contact with each other. . These step portions (11) etc. can be easily formed by resin molding.

Each stationary blade (61) (82) is provided with a seventh blade at the top of the stationary outer cylinder (9) which also serves as a support to the casing (1) side.
The support surface (16) and pressing surface (17) of the stationary blade (61 or 62) are attached to the annular main body (15) shown in the figure, and the spigot retaining portion (
16) and a spacer (6) formed with an engaged portion (19).
0). In this case, the spacer (60
) is also preferably made into a resin. Further, as shown in FIG. 8, thick-walled annular portions (800) may be integrally formed on the outer periphery of each of the stationary blades (81) and (132) in place of the spacer (60).

According to the above configuration, each stationary blade (81) (82) can be molded at once with resin, and the blade (θ10) (θ
20) can also prevent the worker from cutting his or her hand on the edge part. Furthermore, even if fluorine-based or chlorine-based corrosive gas is exhausted from the chamber (21),
Since each stationary blade (81) (62) is made of synthetic resin, it will not be damaged by corrosion. Furthermore, as shown in Figure 9, although resin materials have a large initial content of gas molecules, most of them are released in a short period of time, so once the vacuum has been drawn to a certain extent, the vacuum level The difficulty of being inhibited can also be reduced.

(Effect of the invention) In the present invention, by making the stator blade (6) resin, the stator blade (6)
It is possible to reduce the number of processing steps for the stator blade (6), ensure the formation accuracy of the stationary blade (6), and reduce the fear that the operator will cut his/her hand due to the edge.

Furthermore, even when a chamber filled with corrosive gases such as fluorine or chlorine gases is evacuated in the semiconductor manufacturing sector, the stationary blades (6) will not be damaged by corrosion, resulting in improved durability. can.

Furthermore, although the resin material initially contains a large amount of gas molecules, most of the gas molecules are released in a short period of time, so that the concern that the degree of vacuum will be impaired during actual use can be reduced.

[Brief explanation of the drawing]

Fig. 1 is a vertical sectional view of the vacuum pump of the present invention, Fig. 2 and Fig. 3 are
Figure 4 shows the shape of the moving blade, Figures 4 and 5 show the shape of the stator blade, Figure 6 is an enlarged sectional view showing an example of the structure of the mating part of the stator blade divided into two parts, and Figure 7 shows the shape of the stator blade. The figure is a cross-sectional view of a spacer of a stator blade, FIG. 8 is a cross-sectional view showing another embodiment of a stator blade, and FIG.
10 is a longitudinal sectional view of a conventional pump, and FIGS. 11 and 12 are illustrations of conventional blade processing technology. (2)... Intake port (3)... Exhaust port (5)... Moving blade (6)... Stator vane (7)... Axial flow pump element Applicant Daikin Industries, Ltd. Figure 8 Figure 4 Figure 6 jl 01θ Figure 5 j 6Z σ2θ Figure 8 Closed Figure 10

Claims (1)

[Claims] 1) Between the intake port (2) and the exhaust port (3), there is a rotor blade (5)
An axial pump element (7) in which stator vanes (6) are arranged alternately.
), the stator blade (6)
A molecular vacuum pump characterized by being made of synthetic resin.