JPS63183297A - Turbo molecular pump - Google Patents

Abstract

PURPOSE:To simplify the working operation by forming a plurality of types of moving blades integrally with respective divided drums of a drum fixed to a rotary shaft and divided axially. CONSTITUTION:A rotary shaft 21 having a recess 21a on the center axis of a frame body 5 is rotatably provided. A drum 22 consisting of three divided drums 23-25 is united by bolts 26 and fixed to the rotary shaft 21 to be as a whole formed into a tubular body having a seat. The respective divided drums 23-25 are formed integrally with a plurality of types of moving blades 27-29. Thus, the moving blades can be individually worked by dividing and forming axially the drum to simplify the working operation.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a turbo-molecular pump suitable for use, for example, in the manufacturing process of semiconductor devices.

[Conventional technology]

Generally, when manufacturing semiconductor devices, it is known to use a turbo-molecular pump, which has excellent exhaust performance in a molecular flow region, because it is necessary to form a chamber with a high degree of vacuum.

Conventionally, this type of turbomolecular pump was disclosed in Japanese Patent Application Laid-Open No. 135-1983.
It is disclosed in Japanese Patent No. 694 and is constructed as shown in FIG. To explain this based on the same figure, in the same figure, the part indicated by the reference numeral 1 is fixed on the support 2, and the inlet 1 is
a and a cylindrical casing having a mounting flange 1b, 3 is attached to the inner circumferential surface of this casing l via a spacer 4 and is provided in multiple stages at equal intervals in the axial direction; A frame 6 provided inside the stationary blade 3 and fixed to the upper part of the support 2 is rotatably provided on the central axis of the frame 5, and a rotating shaft 8 has a rotor 7 on the axis. 9 is a bottomed cylindrical drum that is fixed to the tip of the rotating shaft 6 and has a step-shaped outer circumferential surface; These rotor blades are attached and provided in multiple stages at equal intervals in the axial direction, similar to the stationary blades 3 described above. This rotor blade 9 has two types of rotor blades 9a with different blade diameters.

9b. Note that IO is a pipe member attached to the casing 1 via the support 2 and has a discharge port 10a that opens laterally, and 11 is a pipe member fixed to the inside of the frame 5 and provided around the rotor. This is the stator. Further, 12 is a spherical spiral group bearing having a shaft 12a and a shaft support 12b, 13 is a touchdown bearing, and 14 is lubricating oil.

[Problem that the invention seeks to solve]

By the way, in this type of turbomolecular pump, in order to increase the pumping speed and compression ratio, multiple types of rotor blades 9 (9a, 9b) with different average blade diameters, blade angles, or number of blades are used.
Therefore, the rotor blades 9 and the drum 8 were formed separately. As a result, when the drum 8 rotates at high speed,
The centrifugal force causes the rotor blades 9 to separate from the drum 8, resulting in unstable operation accompanied by vibrations, and in the worst case, there is a problem in that the rotor blades 9 collide with the stationary blades 3.

Therefore, as shown in Figure 4, the drum 1 was
Although it is conceivable to fabricate the rotor blades 16a and 16b integrally in the rotor blades 16a and 16b, this has the disadvantage of not only complicating the fabrication process but also increasing the cost.

The present invention was developed in view of these circumstances, and provides a turbo-molecular pump that not only can prevent collisions between rotor blades and stator blades, but also can simplify machining work and reduce machining costs. It provides:

[Means for solving problems]

The turbo-molecular pump according to the present invention includes a drum fixed to a rotating shaft and formed into segments in the axial direction, and a plurality of types of rotor blades are integrally formed in each segment of the drum.

[For production]

In the present invention, even if the drum rotates at high speed, the rotor blades do not separate from the drum, resulting in stable operation.

〔Example〕

FIG. 1 is a cross-sectional view showing a turbomolecular pump according to the present invention, and in the following figures, the same members as in FIGS. 3 and 4 are designated by the same reference numerals, and detailed explanations will be omitted. In the figure, the reference numeral 21 denotes a rotating shaft having a recess 21a in the center of its upper end surface, and is rotatably provided on the central axis of the frame 5. 22 is a drum consisting of three divided drums 23 to 25, each of which is integrated by a bolt 26, and the rotating shaft 21
The entire body is shaped like a cylinder with a bottom.

Each of the divided drums 23 to 25 of this drum 22 has a plurality of types of rotor blades (different average blade diameters, blade angles, or number of blades).
7.28.29 are integrally formed. Further, the central divided drum 24 of the drum 22 is fitted with a spigot into the other divided drums 23° 25 as shown by symbols A and B in the figure. The bottom surface of the divided drum 23 is provided with an annular groove 23a that fits into the tip of the rotating shaft 21 with a pilot fitting.
is formed.

In the turbo molecular pump configured in this way, since the rotor blades 27 to 29 are integrally formed on each of the divided drums 23 to 25, even if the divided drums 23 to 25 rotate at high speed, the centrifugal force causes the rotor blades to 29 are never separated from the drums 23 to 25, resulting in stable operation.

Further, by dividing the drum 22 in the axial direction, it is possible to separately process a plurality of types of rotor blades 27 to 29.

Although the present embodiment shows an example in which the divided drums 23 to 25 are integrated by bolts 26, the present invention is not limited to this, and as shown in FIG. There is no harm in changing it.

Further, although this embodiment shows a case in which the present invention is applied to a vertical pump, it goes without saying that the present invention can be similarly applied to a horizontal pump.

Further, the number of types of rotor blades 27 to 29 in the present invention is not limited to the above-mentioned embodiment, and may be two types, for example, and the number of types can be changed as appropriate.

〔Effect of the invention〕

As explained above, according to the present invention, a drum is provided which is fixed to a rotating shaft and divided in the axial direction, and a plurality of types of rotor blades are integrally formed on each divided drum of this drum.
Even if the drum rotates at high speed, the rotor blades will not separate from the drum due to centrifugal force. Therefore, since the rotational movement of the drum is stable without vibrations as in the conventional case, collisions between the rotor blade and the stationary blade can be prevented. Also,
By dividing the drum in the axial direction, it is possible to separately process a plurality of types of rotor blades, thereby simplifying the processing work and reducing the processing cost.

[Brief explanation of the drawing]

FIG. 1 is a sectional view showing a turbomolecular pump according to the present invention;
FIG. 2 is a sectional view showing another embodiment, and FIGS. 3 and 4 are sectional views showing a conventional turbo molecular pump. 21...Rotating shaft, 22...Drum, 23-25...
・Divided drum, 27-29... Moving blade. Agent Masuo Oiwa Figure 1 Figure 3 Figure 4 Procedural amendment (st) 2. Title of the invention 9-a55'3f/1' software. 3. Relationship with the case of the person making the amendment Patent applicant address 2-2-3 Marunouchi, Chiyoda-ku, Tokyo Name (601) Mitsubishi Electric Corporation Representative Moriya Shiki 4 Agent address Chiyoda-ku, Tokyo Mitsubishi Electric Corporation, 2-2-3 Marunouchi Name (7375) Patent Attorney Masuo Oiwa (lll Sales 03213) 3421 Patent Department) 5, Column 6 for detailed explanation of the invention in the specification to be amended, Contents of the amendment "This drum 7" on page 2, line 11 of the specification is replaced with "this drum 8."
” he corrected.

Claims (1)

[Claims] A turbo-molecular pump comprising a drum fixed to a rotating shaft and divided in the axial direction, and each of the divided drums having a plurality of types of rotor blades integrally formed therein.