JPS62288388A - Turbo-molecular pump device - Google Patents

Abstract

PURPOSE:To simplify the structure of a rotary body by forming a rotor on the peripheral wall of the receseed part of said rotary body and providing a stator in said recessed part being opposite to said rotor. CONSTITUTION:A rotary body 17 has rotor blades 1 on its outer periphery, and a recessed part is formed around its rotary shaft 15. The stator 18 of a motor is provided in the recessed part of the rotary body 17, and the rotor 19 of the motor which is formed integrally with the rotary body 17 is provided on the peripheral wall of the recessed part. Thus, the rotor 19 of the motor is supported by the rotary body 17 positioned on the outer periphery of the motor, while being housed in the rotary body 17. Thereby, the structure of the rotary body can be made simpler than the conventional one, withstanding a large centrifugal force.

Description

Detailed Description of the Invention 3. Detailed Description of the Invention [Field of Industrial Application] This invention relates to a turbo molecular pump (vacuum molecular pump) device tK for realizing high vacuum equipment such as semiconductor manufacturing equipment. It is something.

[Conventional technology]

As a conventional turbo molecular pump device, a magazine (Amer
ican vacuum 5ociety (1983
224-227, A New type of
turbomolecular vacuum pu
mp be-aring").Furthermore, the bearing that supports the rotating body was improved by this inventor, as shown in Fig. 3 in Utility Application No. 1983-78395. In the figure, which is a longitudinal cross-sectional view showing the turbo-molecular pump device, (1) is a rotor blade that sucks fluid, and is provided on the outer periphery of a rotating body that rotates around the rotation axis. 2) is a stator blade placed opposite to the rotor blade (1), and the cylindrical casing (
3) is attached to the inner wall. (4) is rotor A (
1) This is the rotor of the electric motor that drives the rotating body consisting of the rotating shaft (5), and for example, (5) is the stator of the electric motor, which is attached to the rotating shaft α9 by shrink fitting. Fixed to frame GO. -9α4 is a bearing that rotatably supports the rotating shaft (to) of a rotating body. For example, the rotating shaft α9 is supported at its lower and upper parts. Normally (2) is a spherical spiral groove bearing, and 04) is a touch bearing. The down bearing (7) is the fluid inside the device (11a).

(11b), for example, is often an exhaust port for exhausting air out of the device. (9) This is a pace that supports the entire Vt position. a3 is the lubricating oil required for the spherical spiral groove bearing, which is the lower bearing of the rotating body, and normally oil with a very low saturated vapor pressure of, for example, 10 Torr or less at room temperature is used.αG is the turbo molecular pump. A flange for attaching a device, for example, to a device body that requires high vacuum, such as semiconductor manufacturing equipment.

Next, the operation of the turbo-molecular pump device configured as 411f will be explained.

All turbomolecular pumps installed in equipment requiring high vacuum! , Motives (4) and (5), when rotating at high speed with electric current, usually tens of thousands of rpm, the fluid (ll &), (llb ) is exhausted to the outside air through the gap between the rotor blades (1) and stator blades (2), and the pressure inside the device gradually decreases and a high vacuum is achieved. The shape of the blade (2) has been devised to form a unidirectional flow.Even in a turbomolecular pump device, the pressure is lower at the flange αQ of the device, which requires a high stem 22'f, and the exhaust gas Mouth side (7)
The pressure increases as it approaches.

Usually, when the number of rotors R(1) is large, that is, the number of stages is large, it is possible to achieve a high vacuum. In addition, the higher the rotation speed, the better the performance and the smaller and lighter equipment.

Let's talk about rotational performance. Before rotation, that is, when stopped, the rotating body includes a touchdown bearing α4 disposed at the top,
It is supported by the lower bearing, a spherical spiral groove bearing υ. In this way, the rotating body is supported by the electric motor (
When driven by 4) and (5), in the low rotational speed region, it is supported and rotated by both bearings (6) and α4.

However, the rotational speed increases, and at a certain rotational speed, usually several thousand rpm
When the gyro effect of the rotating body reaches more than m,
The rotating body will automatically detach from the upper touchdown bearing α4 and rotate without contact. Also, the lower bearing (6) is in metal contact when stopped, but the rotating body can be rotated. Then, lubricating oil is drawn into the center of the spherical spiral groove bearing (6), and the bearing rotates in a hydrodynamic bearing, that is, a sliding bearing.

[Problem that the invention seeks to solve]

Conventionally, for example, an induction motor was used as an electric motor to drive a rotating body at high speed, so the rotor (4) was fastened to the rotating shaft (toward) by shrink fitting, etc. There was a limit to speeding up. In addition, this invention, which had problems in assembly due to its complicated structure, was made in order to solve the problems mentioned above. Turbomolecular pump device f that is superior to conventional ones in terms of
It is intended to provide.

[Means for solving problems]

The turbo-molecular pump device according to the present invention includes a cylindrical casing having stator blades on its inner wall, a rotor blade disposed facing the stator blade on its outer periphery for sucking fluid, and a recess formed around a rotating shaft. A rotating body, a rotor formed on the rotating body supported by a peripheral wall of a recess, and a stator disposed in the recess facing the rotor, an electric motor for rotating the rotating body having the rotor; a lower bearing formed of a spherical spiral groove bearing which supports the motor at its lower part', and an upper bearing having a touchdown bearing which is disposed in a cylinder holding the stator of the electric motor and supports the rotating body at its upper part. It is something.

[Effect]

The rotating body of this invention has a structure that is easier to assemble compared to conventional equipment, and the rotor has a structure that can withstand greater centrifugal force, so it is possible to realize a faster rotating body and a turbo molecule with good performance. Provide pump equipment.

〔Example〕

An embodiment of the present invention will be described below with reference to the drawings. 1st
Figure (a) is a plan view of a turbomolecular pump device according to an embodiment of the present invention, and Figure (b) is a longitudinal sectional view. In the figure, αη is the rotor l! (1) is a rotating body with a recess formed around the rotating shaft (to) on the outer periphery, (to) is the stator of the electric motor placed in the recess of the rotating body αη, and Q (J is the rotary body αη). The rotor of the electric motor is integrally formed with the rotating body Qη and is fixed to the peripheral wall of the recess, for example, with a built-in permanent magnet.Normally, a synchronous motor is used as the electric motor. (1) is a stator. A cylinder integrated with a base (9) that holds the core of (21a
), (21b), (2]c) are intake holes, (a)
is the lower bearing box, and the fin is the cooling fin. In a turbo molecular pump device configured in this way, the rotor of the electric motor is supported by the rotating body αη located at a known position on the outside.
Since it has a built-in structure in the rotating body αη, the structure of the rotating body αη can be made simpler than before, and it can withstand larger centrifugal force than before, so the rotation speed of the rotating body αη can be increased. It becomes possible to do so. For this reason,
The performance required of turbomolecular pumps will also be improved.

As for rotational performance, in the low rotational speed range, as with the conventional structure, the rotating body α force is rotated via the touchdown bearing α4Jf, and as the rotation increases further, the vibration of the rotating body αη is gradually suppressed. , the upper bearing (141 is non-contact, and the upper bearing (141) is supported and rotated only by the lower bearing (6). As a turbo-molecular pump device having a structure W similar to the above embodiment, a patent application by the present inventor has been proposed. Shomu P Engineering 1491
In this case, the touchdown bearing α is provided on the flange 06, so the intake holes (21a) to (21c) become smaller and the gas (lla) , (llb) is obstructed.

This invention overcomes these problems and makes gas (lla
), (1xb) in that the touchdown bearing α4 is installed using the stator holder, that is, the inner cylinder (1), without interfering with the flow of the air.

Other embodiments of this invention are shown in FIGS. 2(a) and (b) K.
show.

In this figure, (24a) and (24b) are repulsion type radial bearings, for example, repulsion type non-contact magnetic bearings made of permanent magnets or the like. By adopting such a structure, a function is added to prevent the rotating body αη from wobbling in the radial direction and to always maintain the rotating body α at the center of rotation. , it can be a turbo-molecular pump device with excellent rotational performance.

〔Effect of the invention〕

As described above, according to the present invention, there is provided a cylindrical casing having stator blades on the inner wall, a tongue 1 disposed opposite to the stator blades, a rotor blade for sucking fluid on the outer periphery, and a recess around the rotating shaft. A rotating body formed with a rotor, a rotor supported by a peripheral wall of a recess, and a stator disposed opposite to the rotor in the recess, the rotating body having the rotor being rotated. an electric motor, a lower bearing formed by a spherical spiral groove bearing supporting the rotating body at its lower part, and an upper part having a touchdown bearing disposed in a cylinder holding the stator of the electric motor and supporting the rotating body at its upper part; Equipped with bearings, the structure of the rotating body can be simplified, making it easier to assemble, making it smaller than the same company's, and since the rotor has a strong centrifugal force structure, it can operate at higher speeds. This has the effect of providing a turbomolecular pump device with improved performance.

[Brief explanation of drawings]

FIGS. 1(a) and (b) are a plan view and a vertical sectional view showing a turbomolecular pump device according to an embodiment of the present invention, and FIGS. 2(a) and (b) are other embodiments of the invention. A plan view and a longitudinal sectional view showing an example, and FIG. 3 is a longitudinal sectional view showing a conventional turbo molecular device. (1)...Rotor blade, (2)...Stator blade, (3
)...Tubular casing, (2)...Spherical spiral groove bearing, α4...Touchdown bearing, αQ...
Rotating shaft, αη...Rotating body, (to)...Stator of electric motor, 0...'Rotor of WL motor〇In the drawings, the same reference numerals indicate the same or equivalent parts.

Claims (3)

[Claims] (1) A cylindrical casing having stator blades on its inner wall, a rotating body having rotor blades on its outer periphery that are arranged to face the stator blades and suck fluid, and having a recess formed around a rotating shaft; An electric motor having a rotor supported by a peripheral wall and formed on the rotating body, and a stator disposed in the recess facing the rotor, for rotating the rotating body, and supporting the rotating body at its lower part. A turbo-molecular pump device comprising: a lower bearing formed of a spherical spiral groove bearing; and an upper bearing having a touchdown bearing disposed in an inner cylinder holding a stator of the electric motor and supporting the rotating body at its upper part. (2) The turbo-molecular pump device according to claim 1, wherein the upper bearing has a magnetic bearing that prevents the rotating body from wobbling in the radial direction. (3) The turbo-molecular pump device according to claim 2, wherein the magnetic bearing is a repulsion type magnetic bearing.