JPH11280690A - Turbo-molecular pump - Google Patents

Abstract

PROBLEM TO BE SOLVED: To stop the pump safely before the rotating vane of the rotor touches or collides against the fixed vane or other members of the stator by measuring and grasping the relationship in terms of radial position. SOLUTION: In the pump casing of this turbo-molecular pump in which a rotor R and a stator S constitute a vane exhaust zone L1 and a groove exhaust zone L2, a sensor 40 is provided to measure the positional relationship between the rotor R and stator S relative to the diameter. With the output from the sensor 40, positional relationship between the rotor R and the stator S relative to the diameter can be grasped. The pump can be safely stopped before the rotating vane of the rotor touches or collides against the fixed vane or other members of the stator.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

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

[0002]

2. Description of the Related Art FIG. 3 is a sectional view showing the structure of an example of a conventional turbo-molecular pump of this type. This turbo molecule
A blade exhaust part L1 and a groove exhaust part L2 are constituted by a rotor (rotating part) R and a stator (fixed part) S inside the pump casing. The pump casing is mainly composed of a tubular outer casing 14 and a stator S in which a base 15 and a fixed tubular portion 16 are integrated. The rotor R is mainly composed of a main shaft 10 and a rotary cylindrical portion 12.

A drive motor 18 is provided between the main shaft 10 and the fixed cylindrical portion 16, and an upper radial magnetic bearing 2 is provided above and below the drive motor 18.
Zero and lower radial magnetic bearings 22 are provided. The target disk 24a at the lower end of the main shaft 10 and the upper and lower electromagnets 24 on the stator S side are provided below the main shaft 10.
An axial magnetic bearing 24 having a point b is disposed.
With such a configuration, the turbo molecular pump is configured so that the rotor R rotates at a high speed under active control of five axes.

[0004] On the outer periphery of the upper portion of the rotating tubular portion 12, the rotating blades 3 are provided.
0 are integrally provided to constitute an impeller, and the casing 14
Fixed wings 32 alternately arranged with the rotating wings 30
Is provided. And the blade exhaust part L1 which exhausts by the interaction of the rotating blade 30 which rotates at high speed and the stationary blade 32 which is stationary is comprised. Further, a screw groove exhaust portion L2 is provided below the blade exhaust portion L1. That is, the rotary cylindrical portion 12 is provided with a screw groove portion 34 having a screw groove 34 a formed on the outer peripheral surface so as to surround the fixed cylindrical portion 16, while the stator S surrounds the outer circumference of the screw groove portion 34. A thread groove spacer 36 is arranged. Further, the screw groove exhaust portion L2 is a screw groove 34a of the screw groove portion 34 that rotates at a high speed.
Exhaust is performed by the drag action of.

[0005] As described above, a wide-range turbo-molecular pump capable of coping with a wide flow rate range is provided by having the thread groove exhaust portion L2 downstream of the blade exhaust portion L1. In this example, an example is shown in which the screw groove of the screw groove exhaust portion L2 is formed on the rotor R side, but the screw groove is also widely formed on the stator S side.

Although not shown, when exhausting corrosive gas or the like, an inlet is provided in the fixed cylindrical portion 16 and a drive motor 18 and upper and lower radial magnetic bearings 20 above and below it are provided.
And lower radial magnetic bearing 22, target disk 2
4a, an inert gas such as N ₂ gas is supplied and fixed between the main shaft 10 and the fixed cylindrical portion 16 to protect the axial magnetic bearing 24 and the like having the upper and lower electromagnets 24b on the stator S side from corrosive gas and the like. It is also widely practiced to exhaust the gas together with the corrosive gas through the space between the tubular portion 16 and the rotating tubular portion 12.

[0007] In addition, the inert gas such as N ₂ gas causes the reaction by-products generated inside the pump to solidify and adhere to the inside of the pump when exhausting gas that can generate reaction by-products. It also has the effect of reducing it.

[0008]

As described above, the blade exhaust portion L is provided inside the pump casing by the rotor R and the stator S.
1 and the groove exhaust portion L2, the rotor R has an eccentricity and the like, and the rotor exhaustion portion L1
And temperature expansion of the rotor 30 of the groove exhaust part L2 and the rotor 3
0 due to creep expansion or the like of the material constituting the stator S
Not only does the rotor R come into contact with or collide with the fixed wings 32 and the like, but the rotor R is overloaded and stopped, but also a large force is applied to the casing 14 in the radial and circumferential directions.

Due to such an abnormal force, the casing 14
Or breakage of the fixed cylindrical portion 16 or breakage of these joints,
Or there is a possibility that the joint piping part between these and the outside is broken. In addition, these may destroy the entire vacuum system of the processing apparatus in which the turbo-molecular pump is used, causing damage to the processing apparatus itself and products being processed, and may also lead to external emission of the processing gas. . So rotor R
It is desired that the turbo molecular pump be safely stopped before the rotating blades 30 contact or collide with the fixed blades 32 of the stator S.

The present invention has been made in view of the above points, and by measuring and grasping the positional relationship between the rotor R and the stator S in the radial direction, the rotating blades of the rotor R can be attached to the fixed blades of the stator S or the like. It is an object of the present invention to provide a highly safe turbo-molecular pump capable of safely stopping a pump before contact or collision.

[0011]

According to a first aspect of the present invention, there is provided a turbo-molecular pump in which a blade exhaust portion and / or a groove exhaust portion are constituted by a rotor and a stator inside a pump casing. And a sensor for measuring a positional relationship between the rotor and the stator in the radial direction. Thus, the positional relationship of the rotor and the stator in the radial direction can be grasped from the output of the sensor, and the pump can be safely stopped before the rotor blades of the rotor come into contact with or collide with the fixed blades of the stator.

Further, the invention according to claim 2 is characterized in that the sensor is provided on a stator located outside the rotor in the groove exhaust portion.

According to a third aspect of the present invention, the sensor is provided on a stator located inside the rotor of the blade exhaust portion or the groove exhaust portion.

[0014]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a sectional view showing a configuration example of a turbo-molecular pump according to the present invention. In FIG. 1, portions denoted by the same reference numerals as those in FIG. 3 indicate the same portions. The configuration of the present turbo-molecular pump is substantially the same as the conventional turbo-molecular pump shown in FIG. The difference is that a sensor 40 for measuring the positional relationship between the rotor R and the stator S in the radial direction is provided on the thread groove spacer 36 of the stator S located outside the thread groove 34 of the rotor R of the groove exhaust portion L2. It is in.

By providing the sensor 40 on the thread groove spacer 36 of the stator S as described above, the rotor R
Even when the rotor 30 approaches the outer stator S,
Since the output of the sensor 40 can determine the distance between the rotor R and the stator S in the radial direction, the rotor R
The pump can be safely stopped before the pump contacts the stator S.

FIG. 2 is a sectional view showing a configuration example of a turbo-molecular pump according to the present invention. In FIG. 2, portions denoted by the same reference numerals as those in FIG. 3 indicate the same portions. The configuration of the present turbo-molecular pump is substantially the same as the conventional turbo-molecular pump shown in FIG. The difference is that a sensor 41 for measuring the positional relationship between the rotor R and the stator S in the radial direction is provided on the fixed cylindrical portion 16 located inside the rotor R of the groove exhaust portion L2.

As described above, by providing the sensor 41 on the fixed tubular portion 16 located inside the rotor R of the groove exhaust portion L2, the rotating blades 30 of the rotor R
, The distance of the radial positional relationship between the rotor R and the stator S can be ascertained from the output of the sensor 41, so that the pump can be safely stopped before the rotor R comes into contact with the stator S. Can be. In addition, the mounting position of the sensor 41 may be provided on the fixed cylindrical portion 16 of the blade exhaust portion L1.

Further, as described above, the sensor 41 measures the distance between the rotating tubular portion 12 and the fixed tubular portion 16 such that
Since it is provided on the fixed tubular portion 16, N
_{(2) When} exhausting a corrosive gas or the like by supplying an inert gas such as a gas, the sensor 41 is protected from the corrosive gas or the like, and when exhausting a gas that may generate a reaction by-product, a radial direction is used. In order to prevent or reduce the adhesion of the reaction by-product generated inside the pump to the position where the positional relationship is measured, accurate position measurement becomes possible.

The mounting positions of the sensors 40 and 41 in FIGS. 1 and 2 are merely examples, and the mounting positions of these sensors are not limited to those described above. In short, the positional relationship between the rotor and the stator in the radial direction is essential. Any position can be used as long as the position can be measured. Further, the turbo-molecular pump is not limited to the wide-area turbo-molecular pump having both the blade exhaust portion L1 and the groove exhaust portion L2, and may be a turbo-molecular pump having either one.

Here, safely stopping the pump means that:
This also includes so-called failure prediction and / or failure diagnosis, such as displaying a warning or outputting a warning to a controller or the like that starts and controls the turbo molecular pump to indicate a dangerous situation, and stopping the pump.

An example of a sensor for measuring the positional relationship between the rotor R and the stator S in the radial direction includes an eddy current sensor. In the above embodiment, the groove exhaust portion L2
Is shown on the outer periphery of the thread groove portion 34 on the rotor R side, but the same applies when the thread groove is formed on the inner peripheral surface of the thread groove spacer 36 on the stator S side. Of course.

[0022]

As described above, according to the present invention,
A sensor is provided to measure the radial positional relationship between the rotor and the stator, so that the output of this sensor can be used to determine the radial positional relationship between the rotor and the stator. The pump can be safely stopped before contacting or colliding with the stator due to the temperature expansion of the rotor and the creep expansion of the rotor material, such as the exhaust part and the groove exhaust part. The casing does not receive a large amount of force in the radial or circumferential direction on the casing side. It is possible to prevent the joint pipe from being broken or the like. Therefore, it is possible to provide a highly safe turbo-molecular pump so as not to break the entire vacuum system of the processing apparatus using the turbo-molecular pump.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view illustrating a configuration example of a turbo-molecular pump according to the present invention.

FIG. 2 is a cross-sectional view illustrating a configuration example of a turbo-molecular pump according to the present invention.

FIG. 3 is a cross-sectional view showing the configuration of a conventional turbo molecular pump of this type.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 Main shaft 12 Rotating cylindrical part 14 Casing 15 Base 16 Fixed cylindrical part 18 Drive motor 20 Upper radial magnetic bearing 22 Lower radial magnetic bearing 24 Axial magnetic bearing 30 Rotor blade 32 Fixed wing 34 Screw groove part 36 Thread groove part spacer 40 Sensor 41 Sensor

Claims (3)

[Claims] 1. A turbo-molecular pump in which a blade exhaust portion and / or a groove exhaust portion are constituted by a rotor and a stator inside a pump casing, wherein a sensor for measuring a positional relationship between the rotor and the stator in a radial direction is provided. A turbo-molecular pump characterized in that: 2. The turbo-molecular pump according to claim 1, wherein said sensor is provided on a stator located outside a rotor of said groove exhaust portion. 3. The turbo-molecular pump according to claim 1, wherein the sensor is provided on a stator located inside a rotor of the blade exhaust portion or the groove exhaust portion.